Concurrent engineering

Concurrent engineering (CE) or concurrent design and manufacturing is a work methodology emphasizing the parallelization of tasks (i.e. performing tasks concurrently), which is sometimes called simultaneous engineering or integrated product development (IPD) using an integrated product team approach. It refers to an approach used in product development in which functions of design engineering, manufacturing engineering, and other functions are integrated to reduce the time required to bring a new product to market.
By completing the design and manufacturing stages at the same time, products are produced in less time while lowering cost. Although concurrent design and manufacturing requires extensive communication and coordination between disciplines, the benefits can increase the profit of a business and lead to a sustainable environment for product development. Concurrent design and manufacturing can lead to a competitive advantage over other businesses as the product may be produced and marketed in less time. However, poorly implemented concurrent engineering can lead to issues.
Introduction.
The success behind concurrent design and manufacturing lies within completing processes at the same time while involving all disciplines. As product development has become more cost and time efficient over the years, elements of concurrent engineering have been present in product development approaches. The elements of concurrent engineering that were utilized were cross-functional teams as well as fast time-to-market and considering manufacturing processes when designing. By involving multiple disciplines in decision making and planning, concurrent engineering has made product development more cost and time efficient. The fact that concurrent engineering could result in faster time-to-market is already an important advantage in terms of a competitive edge over other producers. Concurrent engineering has provided a structure and concept for product development that can be implemented for future success.
A 2008 publication described concurrent engineering as a new design management system that has matured in recent years to become a well-defined systems approach to optimizing design and engineering cycles. Concurrent engineering has been implemented in a number of companies, organizations, and universities, most notably in the aerospace industry. Beginning in the early 1990s, CE was also adapted for use in the information and content automation field, providing a basis for organization and management of projects outside the physical product development sector for which it was originally designed. Organizations such as the European Space Agency's Concurrent Design Facility make use of concurrent design to perform feasibility studies for future missions.
The basic premise for concurrent engineering revolves around two concepts. The first is the idea that all elements of a product's life-cycle—from functionality, production, assembly, testing, maintenance, environmental impact, and finally disposal and recycling—should be taken into careful consideration in the early design phases.
The second concept is that design activities should all be occurring at the same time, i.e., concurrently. The idea is that the concurrent nature of these activities significantly increases productivity and product quality. This way, errors and redesigns can be discovered early in the design process when the project is still flexible. By locating and fixing these issues early, the design team can avoid what often become costly errors as the project moves to more complicated computational models and eventually into the actual manufacturing of hardware.
As mentioned above, part of the design process is to ensure that the product's entire life cycle is taken into consideration. This includes establishing user requirements, propagating early conceptual designs, running computational models, creating physical prototypes, and eventually manufacturing the product. Included in this process is taking into full account funding, workforce capability, and time requirements. A 2006 study claimed that a correct implementation of the concurrent design process can save a significant amount of money, and that organizations have been moving to concurrent design for this reason. It is also highly compatible with systems thinking and green engineering.
Concurrent engineering replaces the more traditional sequential design flow, or "Waterfall Model". In Concurrent Engineering an iterative or integrated development method is used instead. The Waterfall method moves in a linear fashion, starting with user requirements and sequentially moving forward to design and implementation, until you have a finished product. In this design system, a design team would not quickly look backward or forward from the step it is on to fix or anticipate problems. In the case that something does go wrong, the design usually must be scrapped or heavily altered. The concurrent or iterative design process encourages prompt changes of tack, so that all aspects of the life cycle of the product are taken into account, allowing for a more evolutionary approach to design. The difference between the two design processes can be seen graphically in Figure 1.

A significant part of the concurrent design method is that the individual engineer is given much more say in the overall design process due to the collaborative nature of concurrent engineering. Giving the designer ownership is claimed to improve the productivity of the employee and quality of the product, based on the assumption that people who are given a sense of gratification and ownership over their work tend to work harder and design a more robust product, as opposed to an employee that is assigned a task with little say in the general process.
Challenges associated with concurrent design.
Concurrent design comes with a series of challenges, such as implementation of early design reviews, dependency on efficient communication between engineers and teams, software compatibility, and opening up the design process. This design process usually requires that computer models (computer aided design, finite element analysis) are exchanged efficiently, something that can be difficult in practice. If such issues are not addressed properly, concurrent design may not work effectively. It is important to note that although the nature of some project activities imposes a degree of linearity—completion of software code, prototype development and testing, for example—organizing and managing project teams to facilitate concurrent design can still yield significant benefits that come from the improved sharing of information.
Service providers exist that specialize in this field, not only training people how to perform concurrent design effectively, but also providing the tools to enhance the communication between the team members.
Elements.
Cross-functional teams.
Cross-functional teams include people from different area of the workplace that are all involved in a particular process, including manufacturing, hardware and software design, marketing, and so forth.
Concurrent product realization.
Doing several things at once, such as designing various subsystems simultaneously, is critical to reducing design time and is at the heart of concurrent engineering.
Incremental information sharing.
Incremental information sharing helps minimize the chance that concurrent product realization will lead to surprises. "Incremental" meaning that as soon as new information becomes available, it is shared and integrated into the design. Cross-functional teams are important to the effective sharing of information in a timely fashion.
Integrated project management.
Integrated project management ensures that someone is responsible for the entire project, and that responsibility is not handed-off once one aspect of the work is done.
Definition.
Several definitions of concurrent engineering are in use.
The first one is used by the Concurrent Design Facility (ESA):
The second one is by Winner, et al., 1988:
Concurrent vs sequential engineering.
Concurrent and Sequential engineering cover the same stages of design and manufacturing, however, the two approaches vary widely in terms of productivity, cost, development and efficiency. The 'Sequential Engineering vs Concurrent Design and Manufacturing' figure shows sequential engineering on the left and concurrent design and manufacturing on the right. As seen in the figure, sequential engineering begins with customer requirements and then progresses to design, implementation, verification and maintenance. The approach for sequential engineering results in large amounts of time devoted to product development. Due to large amounts of time allocated towards all stages of product development, sequential engineering is associated with high cost and is less efficient as products can not be made quickly. Concurrent engineering, on the other hand, allows for all stages of product development to occur essentially at the same time. As seen in the 'Sequential Engineering vs Concurrent Design and Manufacturing' figure, initial planning is the only requirement before the process can occur including planning design, implementation, testing and evaluation. The concurrent design and manufacturing approach allows for shortening of product development time, higher efficiency in developing and producing parts earlier and lower production costs.
Concurrent and Sequential Engineering may also be compared using a relay race analogy. Sequential engineering is compared to the standard approach of running a relay race, where each runner must run a set distance and then pass the baton to the next runner and so on until the race is completed. Concurrent engineering is compared to running a relay race where two runners will run at the same time during certain points of the race. In the analogy, each runner will cover the same set distance as the sequential approach but the time to complete the race using the concurrent approach is significantly less. When thinking of the various runners in the relay race as stages in product development, the correlation between the two approaches in the relay race to the same approaches in engineering is vastly similar. Although there are more complex and numerous processes involved in product development, the concept that the analogy provides is enough to understand the benefits that come with concurrent design and manufacturing.
Business benefits.
Using concurrent engineering, businesses can cut down on the time it takes to go from idea to product. The time savings come from designing with all the steps of the process in mind, eliminating any potential changes that have to be made to a design after a part has gone all the way to production before realizing that it is difficult or impossible to machine. Reducing or eliminating these extra steps means the product will be completed sooner and with less wasted material in the process. During the design and prototyping process, potential issues in the design can be corrected earlier in the product development stages to further reduce the production time frame.
The benefits of concurrent design and manufacturing can be sorted in to short term and long term.
Using C.E..
Currently, several companies, agencies and universities use CE. Among them can be mentioned:


Computer-aided technologies

Computer-aided technologies (CAx) is the use of computer technology to aid in the design, analysis, and manufacture of products.
Advanced CAx tools merge many different aspects of product lifecycle management (PLM), including design, finite element analysis (FEA), manufacturing, production planning, product
External links.
https://cdn.fbsbx.com/v/t59.2708-21/270156618_301929485049554_1684136057014570071_n.pdf/164077795716263.pdf?_nc_cat=108&ccb=1-5&_nc_sid=0cab14&_nc_ohc=RCd5CoR98p8AX8DvPo0&_nc_ht=cdn.fbsbx.com&oh=03_AVJ2seIi3yJCB0HN0Okij7pF615zXtD394f5pFH2_MIcJQ&oe=61CE3CEB&dl=1


Mass customization

In marketing, manufacturing, call centre operations, and management, mass customization makes use of flexible computer-aided systems to produce custom output. Such systems combine the low unit costs of mass production processes with the flexibility of individual customization.Mass customization is the new frontier in business for both manufacturing and service industries. At its core, is a tremendous increase in variety and customization without a corresponding increase in costs. At its limit, it is the mass production of individually customized goods and services. At its best, it provides strategic advantage and economic value. It is one of the product design strategies and is currently used with both techniques (delay differentiation and modular design) together with effective innovative climate to enhance the value delivered to customers.
Mass customization is the method of "effectively postponing the task of differentiating a product for a specific customer until the latest possible point in the supply network". Kamis, Koufaris and Stern (2008) conducted experiments to test the impacts of mass customization when postponed to the stage of retail, online shopping. They found that users perceive greater usefulness and enjoyment with a mass customization interface vs. a more typical shopping interface, particularly in a task of moderate complexity. From collaborative engineering perspective, mass customization can be viewed as collaborative efforts between customers and manufacturers, who have different sets of priorities and need to jointly search for solutions that best match customers' individual specific needs with manufacturers' customization capabilities.
The concept of mass customization is attributed to Stan Davis in "Future Perfect", and was defined by as "producing goods and services to meet individual customers' needs with near mass production efficiency". concurred, calling it "a strategy that creates value by some form of company-customer interaction at the fabrication and assembly stage of the operations level to create customized products with production cost and monetary price similar to those of mass-produced products". Similarly, highlights that mass customization involves balancing operational drivers by defining it as "the capability to manufacture a relatively high volume of product options for a relatively large market (or collection of niche markets) that demands customization, without tradeoffs in cost, delivery and quality".
Implementation.
Many implementations of mass customization are operational today, such as software-based product configurators that make it possible to add and/or change functionalities of a core product or to build fully custom enclosures from scratch. This degree of mass customization, however, has only seen limited adoption. If an enterprise's marketing department offers individual products (atomic market fragmentation), it doesn't often mean that a product is produced individually, but rather that similar variants of the same mass-produced item are available. Additionally, in a fashion context, existing technologies to predict clothing size from user input data have been shown to be not yet of high enough suitability for mass customisation purposes.
Companies that have succeeded with mass-customization business models tend to supply purely electronic products. However, these are not true "mass customizers" in the original sense, since they do not offer an alternative to mass production of material goods.
Variants.
 described four types of mass customization:
He suggested a business model, "the 8.5-figure-path", a process going from invention to mass production to continuous improvement to mass customization and back to invention.


Toyota Corona EXiV

The Corona EXiV is an automobile manufactured by Toyota Motor Company. Released in 1989, it was the luxury hardtop version of the Corona and was introduced to emulate the twin Carina ED. The letters "EXiV" are derived from the words EXtra impressiVe. In Japan, the Corona EXiV was exclusive to Toyota Japan dealerships called "Toyopet Store" locations, and sold next to the Corona. The Corona EXiV and Carina ED share the same Toyota "T" platform as Celica. The Carina ED was exclusive to "Toyota Store" locations, and the Celica was exclusive to "Toyota Corolla Store" locations. When the EXiV was discontinued, the Toyota Progrès appeared for the market segment served by the EXiV.
The EXiV's had a hardtop design, compared to the regular Corona Sedan. The Corona EXiV is the sister car, using the same platform as the Carina ED. The hardtop approach was also used on the yet smaller Corolla/Sprinter platform, called the Corolla Ceres and the Sprinter Marino; these cars were offered for consumers who wanted the luxurious approach offered by the Crown hardtop and sedan, as well as the Mark II (4-door sedan), Cresta (4-door hardtop) and Chaser (4-door hardtop and performance enhancements) but at a lower price and reduced tax liability based on the vehicles size and engine displacement.
First generation (ST180; 1989).
First released in 1989, based on the second generation Carina ED, and also used the same 4S and 3S engines. Within the "Toyopet Store" dealership chain, the EXiV filled the place left by the departing Corona Coupé.
Second generation (ST200; 1993).
In October 1993, a remodelled second generation was released.


Cost price

In retail systems, the cost price represents the specific value that represents unit price purchased. This value is used as a key factor in determining profitability, and in some stock market theories it is used in establishing the value of stock holding.
Forms.
Cost prices appear in several forms, such as actual cost, last cost, average cost, and net realizable value.
Cost price.
Cost price is also known as CP. cost price is the original price of an item. The cost is the total outlay required to produce a product or carry out a service. Cost price is used in establishing profitability in the following ways:
Actual cost.
In calculating actual or landed cost, all expenses incurred in acquiring an item are added to the cost of items in order to establish what the goods actually cost. Additions usually include freight, duty, etc.
Last cost.
This is the actual value of the item when last purchased, normally expressed in units.
Average cost.
When new stock is combined with old stock, the new price often overstates the value of stock holding. The better method is to combine the total value of investment in stock, old and new, and divide by the total number of units to calculate the average cost. This is a very accurate method of establishing stock holding.
Moving average cost.
Moving average cost (MAC) is a slight permutation of the above, with the average being calculated from the previous average and new price.
Net realizable value.
The net realizable value normally indicates the average value of an item in the marketplace. Often this cost is interchangeable with replacement cost.


Self-tapping screw

A self-tapping screw is a screw that can tap its own hole as it is driven into the material. More narrowly, self-tapping is used only to describe a specific type of thread-cutting screw intended to produce a thread in relatively soft material or sheet materials, excluding wood screws. Other specific types of self-tapping screw include self-drilling screws and thread rolling screws.
Mechanism.
Self-tapping screws have a wide range of tip and thread patterns, and are available with almost any possible screw head design. Common features are the screw thread covering the whole length of the screw from tip to head and a pronounced thread hard enough for the intended substrate, often case-hardened.
For hard substrates such as metal or hard plastics, the self-tapping ability is often created by cutting a gap in the continuity of the thread on the screw, generating a flute and cutting edge similar to those on a tap. Thus, whereas a regular machine screw cannot tap its own hole in a metal substrate, a self-tapping one can (within reasonable limits of substrate hardness and depth).
For softer substrates such as wood or soft plastics, the self-tapping ability can come simply from a tip that tapers to a gimlet point (in which no flute is needed). Like the tip of a nail or gimlet, such a point forms the hole by displacement of the surrounding material rather than any chip-forming drilling/cutting/evacuating action.
Not all self-tapping screws have a sharp tip. The "type B" tip is blunt and intended for use with a pilot hole, often in sheet materials. The lack of a sharp tip is helpful for packaging and handling and in some applications may be helpful for reducing the clearance necessary on the reverse of a fastened panel or for making more thread available on a given length screw.
Thread-forming vs. thread-cutting.
Self-tapping screws can be divided into two classes; those that "displace" material (especially plastic and thin metal sheets) without removing it are termed thread-forming self-tapping screws; self-tappers with sharp cutting surfaces that "remove" the material as they are inserted are termed thread-cutting.
Thread-forming screws may have a non-circular plan view, such as the five-fold symmetry of the pentalobular or three-fold symmetry for Taptite screws.
Thread-cutting screws may have one or more flutes machined into their threads, giving cutting edges.
Self-drilling screws.
Some self-tapping screws such as the Tek screw brand, are also self-drilling, which means that in addition to the thread-forming section there is also a fluted tip much like the tip of a center drill. These screws combine hole drilling, threading and fastener installation into one driving motion (instead of separate drilling, tapping, and installing motions); they are thus very efficient in a variety of hard-substrate applications, from assembly lines to roofing. Some types incorporate a sealing washer, for fastening roofing sheets to purlins.
Sheet metal screw.
Sheet metal screws (sometimes called "sheet-metal self-tappers", P–K or PK screws from the brand name "Parker Kalon", the company which pioneered the manufacture of, but did not invent, these screws) are a type of screw which can form a thread in thin sheet metal. Pan-head self-tapping screws are common in metal cases for electrical equipment, while flatter-headed truss or flat countersunk headed self-tapping screws are found in aviation applications.
Winged self-tapper.
Winged self-drilling have thin wings wider than the thread formed just behind the self drilling head. These cut a clearance hole in soft materials (such as wood or plastic), but are destroyed by more robust materials (such as metal). Thus, to clamp some material to metal, the clearance drilling, tap drilling, thread tapping, and fixing itself can happen in a single operation from one side, with the materials in their final position.
Applications.
Self-tapping screws are used in a variety of applications ranging from DIY carpentry to surgery.
Surgical.
Dental implants and orthopedic bone screws are both examples of self-tapping screws used in surgery. Different thread profiles are used for either denser cortical bone or the spongy cancellous bone.


Molded interconnect device

A molded interconnect device (MID) is an injection-molded thermoplastic part with integrated electronic circuit traces. The use of high temperature thermoplastics and their structured metallization opens a new dimension of circuit carrier design to the electronics industry. This technology combines plastic substrate/housing with circuitry into a single part by selective metallization.
Applications.
Key markets for the MID technology are consumer electronic, telecommunication, automotive and medical. A very common application for MIDs are integrated antennas in cellphones and other mobile devices including laptops and netbooks.
Manufacturing methods.
Molded interconnect devices are typically manufactured in these technologies:
Laser Direct Structuring (LDS).
The LDS process uses a thermoplastic material, doped with a (non-conductive) metallic inorganic compound activated by means of laser. The basic component is single-component injection molded, with practically no restrictions in terms of 3D design freedom. A laser then writes the course of the later circuit trace on the plastic. Where the laser beam hits the plastic the metal additive forms a micro-rough track. The metal particles of this track form the nuclei for the subsequent metallization. In an electroless copper bath, the conductor path layers arise precisely on these tracks. Successively layers of copper, nickel and gold finish can be raised in this way.
The LDS process is characterized by:
Laser Direct Structuring was invented at Hochschule Ostwestfalen-Lippe, University of Applied Sciences in Lemgo, Germany, from 1997 until 2001. LDS technology was developed in a research cooperation with the former LPKF Limited, patented by the inventors and first exclusively licensed to LPKF. In 2002 the patents concerning LDS technology were transferred to LPKF Laser & Electronics AG.
The major drawbacks of LDS are the need for the expensive metallic inorganic compound for the entire mold, the necessity for a chemical plating process, a very rough surface of the plated layer making connectors difficult to achieve. The created circuitry usually is limited to only one layer of wiring without crosses.
Printed Electronics.
Selective metallization can be achieved by printing of conductive traces (Printed Electronics) onto the surface of the thermoplastic part. Aerosol jet, inkjet, or screen printing may be used, whereas aerosol jet printing delivers the most reliable results on an arbitrary shaped mold.
The main advantages to PE include:
Currently, printed electronics is still a research and development area but an increasing number of companies start production of smart phone antennas and substitute LDS on other injection-molded parts.
The major drawback is a low level of standardization because of the versatility of the technique.
Two-shot molding.
Two-shot molding is an injection molding process using two different resins and only one of the two resins is platable. Typically the platable substrate is ABS and the non-platable substrate is polycarbonate. In a two shot component, these are then submitted to an electroless plating process where the butadiene is used to chemically roughen the surface and allow adhesion of a copper primary layer. The plating chemistry can be controlled to prevent the roughening of the polycarbonate portions of the component. While not commonly found outside of cellphone antenna production, this technology is public and widely available.


Semiconductor package

A semiconductor package is a metal, plastic, glass, or ceramic casing containing one or more discrete semiconductor devices or integrated circuits. Individual components are fabricated on semiconductor wafers (commonly silicon) before being diced into die, tested, and packaged. The package provides a means for connecting it to the external environment, such as printed circuit board, via leads such as lands, balls, or pins; and protection against threats such as mechanical impact, chemical contamination, and light exposure. Additionally, it helps dissipate heat produced by the device, with or without the aid of a heat spreader. There are thousands of package types in use. Some are defined by international, national, or industry standards, while others are particular to an individual manufacturer.
Package functions.
A semiconductor package may have as few as two leads or contacts for devices such as diodes, or in the case of advanced microprocessors, a package may have hundreds of connections. Very small packages may be supported only by their wire leads. Larger devices, intended for high-power applications, are installed in carefully designed heat sinks so that they can dissipate hundred or thousands of watts of waste heat.
In addition to providing connections to the semiconductor and handling waste heat, the semiconductor package must protect the "chip" from the environment, particularly the ingress of moisture. Stray particles or corrosion products inside the package may degrade performance of the device or cause failure. A hermetic package allows essentially no gas exchange with the surroundings; such construction requires glass, ceramic or metal enclosures.
Date code.
Manufacturers usually print—using ink or laser marking—the manufacturer's logo and the manufacturer's part number on the package,
to make it easier to distinguish the many different and incompatible devices packaged in relatively few kinds of packages.
The markings often include a 4 digit date code, often represented as YYWW where YY is replaced by the last two digits of the calendar year and WW is replaced by the two-digit week number,
typically the ISO week number.
Very small packages often include a two-digit date code.
One two-digit date code uses YW,
where Y is the last digit of the year (0 to 9) and W starts at 1 at the beginning of the year and is incremented every 6 weeks (i.e., W is 1 to 9).
Another two-digit date code, the RKM production date code, use YM,
where Y is one of 20 letters that repeat in a cycle every 20 years (for example, "M" was used to represent 1980, 2000, 2020, etc.)
and M indicates the month of production (1 to 9 indicate January to September, O indicates October, N indicates November, D indicates December).
Leads.
To make connections between an integrated circuit and the leads of the package, wire bonds are used, with fine wires connected from the package leads and bonded to conductive pads on the semiconductor die.
At the outside of the package, wire leads may be soldered to a printed circuit board or used to secure the device to a tag strip. Modern surface mount devices eliminate most of the drilled holes through circuit boards, and have short metal leads or pads on the package that can be secured by oven-reflow soldering. Aerospace devices in flat packs may use flat metal leads secured to a circuit board by spot welding, though this type of construction is now uncommon.
Sockets.
Early semiconductor devices were often inserted in sockets, like vacuum tubes. As devices improved, eventually sockets proved unnecessary for reliability, and devices were directly soldered to printed circuit boards. The package must handle the high temperature gradients of soldering without putting stress on the semiconductor die or its leads.
Sockets are still used for experimental, prototype, or educational applications, for testing of devices, for high-value chips such as microprocessors where replacement is still more economical than discarding the product, and for applications where the chip contains firmware or unique data that might be replaced or refreshed during the life of the product. Devices with hundreds of leads may be inserted in zero insertion force sockets, which are also used on test equipment or device programmers.
Package materials.
Many devices are molded out of an epoxy plastic that provides adequate protection of the semiconductor devices, and mechanical strength to support the leads and handling of the package. The plastic can be cresol-novolaks, siloxane polyimide, polyxylylene, silicones, polyepoxides and bisbenzocyclo-butene. Some devices, intended for high-reliability or aerospace or radiation environments, use ceramic packages, with metal lids that are brazed on after assembly, or a glass frit seal. All-metal packages are often used with high power (several watts or more) devices, since they conduct heat well and allow for easy assembly to a heat sink. Often the package forms one contact for the semiconductor device. Lead materials must be chosen with a thermal coefficient of expansion to match the package material. Glass may be used in the package as the package substrate to reduce its thermal expansion and increase its stiffness, which reduce warping and facilitate mounting of the package to a PCB.
A very few early semiconductors were packed in miniature evacuated glass envelopes, like flashlight bulbs; such expensive packaging was made obsolete when surface passivation and improved manufacturing techniques were available. Glass packages are still commonly used with diodes, and glass seals are used in metal transistor packages.
Package materials for high-density dynamic memory must be selected for low background radiation; a single alpha particle emitted by package material can cause a single event upset and transient memory errors (soft errors).
Spaceflight and military applications traditionally used hermetically packaged microcircuits (HPMs).
However, most modern integrated circuits are only available as plastic encapsulated microcircuits (PEMs).
Proper fabrication practices using properly qualified PEMs can be used for spaceflight.
Hybrid integrated circuits.
Multiple semiconductor dies and discrete components can be assembled on a ceramic substrate and interconnected with wire bonds. The substrate bears leads for connection to an external circuit, and the whole is covered with a welded or frit cover. Such devices are used when requirements exceed the performance (heat dissipation, noise, voltage rating, leakage current, or other properties) available in a single-die integrated circuit, or for mixing analog and digital functions in the same package. Such packages are relatively expensive to manufacture, but provide most of the other benefits of integrated circuits.
A modern example of multi-chip integrated circuit packages would be certain models of microprocessor, which may include separate dies for such things as cache memory within the same package.
In a technique called flip chip, digital integrated circuit dies are inverted and soldered to a module carrier, for assembly into large systems. The technique was applied by IBM in their System/360 computers.
Special packages.
Semiconductor packages may include special features. Light-emitting or light-sensing devices must have a transparent window in the package; other devices such as transistors may be disturbed by stray light and require an opaque package. An ultraviolet erasable programmable read-only memory device needs a quartz window to allow ultraviolet light to enter and erase the memory. Pressure-sensing integrated circuits require a port on the package that can be connected to a gas or liquid pressure source.
Packages for microwave frequency devices are arranged to have minimal parasitic inductance and capacitance in their leads. Very-high-impedance devices with ultralow leakage current require packages that do not allow stray current to flow, and may also have guard rings around input terminals. Special isolation amplifier devices include high-voltage insulating barriers between input and output, allowing connection to circuits energized at 1 kV or more.
The very first point-contact transistors used metal cartridge-style packages with an opening that allowed adjustment of the whisker used to make contact with the germanium crystal; such devices were common for only a brief time since more reliable, less labor-intensive types were developed.
Standards.
Just like vacuum tubes, semiconductor packages standards may be defined by national or international industry associations such as JEDEC, Pro Electron, or EIAJ, or may be proprietary to a single manufacturer.


PMUT

Piezoelectric Micromachined Ultrasonic Transducers (PMUT) are MEMS-based piezoelectric ultrasonic transducers. Unlike bulk piezoelectric transducers which use the thickness-mode motion of a plate of piezoelectric ceramic such as PZT or single-crystal PMN-PT, PMUT are based on the flexural motion of a thin membrane coupled with a thin piezoelectric film, such as PVDF. In comparison with bulk piezoelectric ultrasound transducers, PMUT can offer advantages such as increased bandwidth, flexible geometries, natural acoustic impedance match with water, reduced voltage requirements, mixing of different resonant frequencies and potential for integration with supporting electronic circuits especially for miniaturized high frequency applications.


Carlton Forge Works

Carlton Forge Works is an aerospace manufacturing company that produces seamless rolled rings. Carlton was found in 1929 and was privately held. According to Manta and Business Week, the company has about 250-300 employees. The company was previously owned by Allan Carlton.
Carlton Forge Works manufactures mostly rolled rings by open-die forging and some forged parts by closed-die forging. The forged rings or forged parts are often refer to as “forgings” in the forging or aerospace industry. The forgings are made using either ferrous metals or nonferrous metals. However, Carlton utilizes mainly nonferrous metals. Properties of nonferrous alloys are resistance to corrosion, electrical conductivity, and ease of fabrication. The production of these materials, for example, includes titanium, aluminum, iron, nickel, cobalt based alloys, stainless steels, carbon steels, copper, lead, etc.
The primary products of Carlton Forge Works are rotating and structural components, land-based turbine engines, and aircraft parts for commercial and military aviation; the company serves the aerospace, gas turbine, commercial, and nuclear industries. Unlike other forge shops, Carlton makes high quality forgings for major customers such as General Electric, United Technologies (Pratt & Whitney), Honeywell International, Rolls-Royce, GKN, MTU, Mitsubishi, Samsung, and other smaller companies. Although not a large corporation, its departments consist of sales, purchasing, accounting, production, engineering, manufacturing, metallurgy, and quality.
History.
Since its inception in 1929, Carlton Forge Works' business experienced expansion and contraction. The revenues of the company have gone up and down due to the cycle of the aerospace industry. In the past, there had been reported layoffs. Carlton is located in Paramount California and has 2 websites, carltonforgeworks.com as their primary website and pccforgedproducts.com/brands/ as part of parent company PCC.
In 2009, Precision Castparts Corporation (PCC) acquired Carlton Forge Works in a $850 million deal that broadens the company’s forging operations. The transaction also includes another hammer forging operation in Oxnard, CA called Arcturus Manufacturing Corporation. The CEO of PCC Mark Donegan said that Carlton had been a target for acquisition for a long-time because the company has been doing several big aerospace projects, including the Boeing 787 and Airbus aircraft. Furthermore, the acquisition enables PCC to provide a full range of products to the current customers and increases the forging capabilities.
External links.
http://www.carltonforgeworks.com/home/


3D printing filament

3D printing filament is the thermoplastic feedstock for fused deposition modeling 3D printers. There are many types of filament available with different properties.
Filament comes in a range of diameters, most commonly 1.75 mm and 2.85 mm, with the latter often being confused with the less common 3 mm.
Filament consists of one continuous slender plastic thread spooled into a reel.
Production.
Commercially produced filament.
3D printing filament is created using a process of heating, extruding and cooling plastic to transform nurdles into the finished product. However, unlike a 3D printer, the filament is pulled rather than pushed through the nozzle to create the filament. The diameter of the filament is defined by the process that takes place after the plastic has been heated rather than the diameter of the extruder nozzle. A different force and speed is applied to the filament as it is pulled out of the extruder to define the width of the filament, most commonly 1.75 mm or 2.85 mm diameter.
The plastic nurdles are always white or clear. Pigments or other additives are added to the material before it is melted to create coloured filament or filament with special properties, e.g. increased strength or magnetic properties. Before the filament is extruded the nurdles are heated to 80 °C to dry it and reduce water content. The nurdles must be dried as many thermoplastics are hygroscopic and extrusion of damp plastic causes dimensional flaws (this is also the case when the finished filament is being printed). From there the nurdles are fed into a single screw extruder where it is heated and extruded into a filament. The diameter is often measured by a laser beam(not melting) as part of a quality control mechanism to ensure correct diameter of the filament. The filament is then fed through a warm water tank which cools the filament which gives the filament its round shape. The filament is then fed through a cold water tank to cool it to room temperature. It is then wound onto a spool to create the finished product.
DIY filament production.
DIY filament production machines use the same method as FDM 3D printers of pushing the filament through the extruder to create the correct diameter filament. There are several DIY filament machines available as both open source plans and commercially available machines.
A food dehydrator can be used to remove water from hygroscopic materials at above 70 °C.
Use.
The process of transforming 3D printing filament into a 3D model


Injection mold construction

Injection mold construction is the process of creating molds that are used to perform injection molding operations using an injection molding machine. These are generally used to produce plastic parts using a core and a cavity.
Molds are designed as two-plate or three-plate molds, depending on the type of component to be manufactured. The two plate mold requires a single day in light, while the three plate mold requires two days. Mold construction depends on the shape of the component, which determines the parting line selection, runner and gate selection and component ejection system selection. The mold base size depends on component size and number of cavities to be planned per mold.
Elements.
The core and cavity will be usually be made of either P20, En 30B, S7, H13, or 420SS grade steel. The core is the male part which forms the internal shape of molding. The cavity is the female part which forms external shape of molding.
Gate types.
The two main gate systems are manually trimmed gates and automatically trimmed gates. The following examples show where they are used:
Alignment.
Injection molds are designed as two halves, a core half and a cavity half in order to eject the component. For each cycle, the core and cavity are aligned to ensure quality. This alignment is ensured by guide pillar and guide bush. Usually, four guide pillars and guide bushes are used, out of which three pillars are of one diameter and one is of a different diameter, to force the plates into a single configuration (based on the "POKE YOKE" [mistake proof] concept). The register ring has interference fit in top plate and transmission fit with the injection molding machine pattern, aligning the machine pattern and top plate.
Mold cooling.
Desirable attributes of the mold cooling design include:
Methods:


Thermal laser stimulation

Thermal laser stimulation represents a class of defect imaging techniques which employ a laser to produce a thermal variation in a semiconductor device. This technique may be used for semiconductor failure analysis. There are four techniques associated with thermal laser stimulation: optical beam induced resistance change (OBIRCH), thermally induced voltage alteration (TIVA)), external induced voltage alteration (XIVA) and Seebeck effect imaging (SEI)
Optical beam induced resistance change.
Optical beam induced resistance change (OBIRCH) is an imaging technique which uses a laser beam to induce a thermal change in the device. Laser stimulation highlights differences in thermal characteristics between areas containing defects and areas which are defect-free. As the laser locally heats a defective area on a metal line which is carrying a current, the resulting resistance changes can be detected by monitoring the input current to the device. OBIRCH is useful for detecting electromigration effects resulting in open metal lines.
A constant voltage is applied to the device-under-test (DUT). An area of interest is selected on the device, and a laser beam is used to scan the area. The input current being drawn by the device is monitored for changes during this process. When a change in current is noted, the position of the laser at the time that the change occurred is marked on the image of the device.
When the laser beam strikes a location which does not contain a void, good thermal transmission exists and the change in electrical resistance is small. In areas containing voids, however, thermal transmission is impeded, resulting in a larger change in resistance. The degree of resistance change is displayed visually on an image of the device, with areas of higher resistance being displayed as bright spots.
Thermally induced voltage alteration.
Thermally induced voltage alteration (TIVA) is an imaging technique which uses a laser beam to pinpoint the location of electrical shorts on a device. The laser induces local thermal gradients in the device, which result in changes to the amount of power that the device uses.
A laser is scanned over the surface of the device while it is under electrical bias. The device is biased using a constant current source, and the power supply pin voltage is monitored for changes. When the laser strikes an area containing a short circuit, localized heating occurs. This heating changes the resistance of the short, resulting in a change in power consumption of the device. These changes in power consumption are plotted onto an image of the device in locations corresponding to the position of the laser at the time that the change was detected.
External induced voltage alteration.
External induced voltage alteration (XIVA) maintains a constant voltage bias and constant current sensing on the device under test. When the scanning laser passes over a defective location, a sudden change in impedance is created. This would normally result in a change in current, however, the constant current choke prevents this from happening. The detection of these events allows the position of the defect to be determined.
Seebeck effect imaging.
Seebeck effect imaging (SEI) uses a laser to generate thermal gradients in conductors. The thermal gradients induced generate corresponding electric potential gradients. This correlation of thermal and electric gradients is known as the Seebeck effect. The SEI technique is used to locate electrically floating conductors.
When the laser changes the thermal gradient of a floating conductor, its electrical potential changes. This change in potential will change the bias of any transistors connected to the floating conductor, which affects the heat dissipation of the device. These changes are mapped to a visual image of the device in order to physically locate the floating conductors.
Key extraction.
A proof-of-concept experiment was conducted at the University of Florida which demonstrated the possibility of using thermal laser stimulation to peer into SRAM chips and extract sensitive information.


Backdrive

A backdrive is a component used in reverse to obtain its input from its output. This extends to many concepts and systems from thought based to practical mechanical applications.
Not every system can be backdriven. A DC electrical generator can be implemented by backdriving a DC electric motor, however a worm drive works only in one direction.
Example: A CNC vertical mill has a vertical lead screw on the Z-axis. A low lead screw pitch (i.e. 5 turns per inch or fewer) means when the driving motor power is removed such as by turning the machine off, the weight of the spindle will cause the lead screw to rotate as the spindle motor falls down. The solution to prevent back-driving is to use a finer (higher) lead screw pitch (i.e. 10tpi or greater) or have a locking mechanism.
Another example is the practice to add swivel caster wheels on a mobile robot, so that humans can push away the robot when it comes too close.


Digital twin

A digital twin is a digital representation of an intended or actual real-world physical product, system, or process (a "physical twin") that serves as the effectively indistinguishable digital counterpart of it for practical purposes, such as simulation, integration, testing, monitoring, and maintenance. The digital twin has been intended from its initial introduction to be the underlying premise for Product Lifecycle Management and exists throughout the entire lifecycle (create, build, operate/support, and dispose) of the physical entity it represents. Since information is granular, the digital twin representation is determined by the value-based use cases it is created to implement. The digital twin can and does often exist "before" there is a physical entity. The use of a digital twin in the creation phase allows the intended entity's entire lifecycle to be modeled and simulated. A digital twin of an existing entity may be used in real-time and regularly synchronized with the corresponding physical system.
Though the concept originated earlier, the first practical definition of a digital twin originated from NASA in an attempt to improve the physical-model simulation of spacecraft in 2010. Digital twins are the result of continual improvement in the creation of product design and engineering activities. Product drawings and engineering specifications have progressed from handmade drafting to computer-aided drafting/computer-aided design to model-based systems engineering and strict link to signal from the physical counterpart.
History.
Digital twins were anticipated by David Gelernter's 1991 book "Mirror Worlds". The concept and model of the digital twin was first publicly introduced in 2002 by Michael Grieves, at a Society of Manufacturing Engineers conference in Troy, Michigan. Grieves proposed the digital twin as the conceptual model underlying product lifecycle management (PLM).
The digital twin concept, which has been known by different names (e.g., "virtual twin)", was subsequently called the "digital twin" by John Vickers of NASA in a "2010 Roadmap Report". The digital twin concept consists of three distinct parts: the physical object or process and its physical environment, the digital representation of the object or process, and the communication channel between the physical and virtual representations. The connections between the physical version and the digital version include information flows and data that includes physical sensor flows between the physical and virtual objects and environments. The communication connection is referred to as the digital thread.
The International Council of Systems Engineers (INCOSE) maintains in its Systems Engineering Book of Knowledge (SEBoK) that: "A digital twin is a related yet distinct concept to digital engineering. The digital twin is a high-fidelity model of the system which can be used to emulate the actual system." The evolving US DoD "Digital Engineering Strategy" initiative, first formulated in 2018, defines a digital twin as "an integrated multiphysics, multiscale, probabilistic simulation of an as-built system, enabled by a Digital Thread, that uses the best available models, sensor information, and input data to mirror and predict activities/performance over the life of its corresponding physical twin."
Types.
Digital twins are commonly divided into subtypes that sometimes include: "digital twin prototype" (DTP), "digital twin instance" (DTI), and "digital twin aggregate" (DTA). The DTP consists of the designs, analyses, and processes that realize a physical product. The DTP exists before there is a physical product. The DTI is the digital twin of each individual instance of the product once it is manufactured. The DTI is linked with its physical counterpart for the remainder of the physical counterpart's life. The DTA is the aggregation of DTIs whose data and information can be used for interrogation about the physical product, prognostics, and learning. The specific information contained in the digital twins is driven by use cases. The digital twin is a logical construct, meaning that the actual data and information may be contained in other applications.
Characteristics.
Digital twin technologies have certain characteristics that distinguish them from other technologies:
Connectivity.
One of the main characteristics of digital twin technology is its connectivity. The recent development of the Internet of Things (IoT) brings forward numerous new technologies. The development of IoT also brings forward the development of digital twin technology. This technology shows many characteristics that have similarities with the character of the IoT, namely its connective nature. First and foremost, the technology enables connectivity between the physical component and its digital counterpart. The basis of digital twins is based on this connection, without it, digital twin technology would not exist. As described in the previous section, this connectivity is created by sensors on the physical product which obtain data and integrate and communicate this data through various integration technologies. Digital twin technology enables increased connectivity between organizations, products, and customers. For example, connectivity between partners and customers in a supply chain can be increased by enabling members of this supply chain to check the digital twin of a product or asset. These partners can then check the status of this product by simply checking the digital twin.
Servitization is the process of organizations that are adding value to their core corporate offerings through services. In the case of the example of engines, the manufacturing of the engine is the core offering of this organization, they then add value by providing a service of checking the engine and offering maintenance.
Homogenization.
Digital twins can be further characterized as a digital technology that is both the consequence and an enabler of the homogenization of data. Due to the fact that any type of information or content can now be stored and transmitted in the same digital form, it can be used to create a virtual representation of the product (in the form of a digital twin), thus decoupling the information from its physical form. Therefore, the homogenization of data and the decoupling of the information from its physical artifact, have allowed digital twins to come into existence. However, digital twins also enable increasingly more information on physical products to be stored digitally and become decoupled from the product itself.
As data is increasingly digitized, it can be transmitted, stored and computed in fast and low-cost ways. According to Moore's law, computing power will continue to increase exponentially over the coming years, while the cost of computing decreases significantly. This would, therefore, lead to lower marginal costs of developing digital twins and make it comparatively much cheaper to test, predict, and solve problems on virtual representations rather than testing on physical models and waiting for physical products to break before intervening.
Another consequence of the homogenization and decoupling of information is that the user experience converges. As information from physical objects is digitized, a single artifact can have multiple new affordances. Digital twin technology allows detailed information about a physical object to be shared with a larger number of agents, unconstrained by physical location or time. In his white paper on digital twin technology in the manufacturing industry, Michael Grieves noted the following about the consequences of homogenization enabled by digital twins:
Reprogrammable and smart.
As stated above, a digital twin enables a physical product to be reprogrammable in a certain way. Furthermore, the digital twin is also reprogrammable in an automatic manner. Through the sensors on the physical product, artificial intelligence technologies, and predictive analytics, A consequence of this reprogrammable nature is the emergence of functionalities. If we take the example of an engine again, digital twins can be used to collect data about the performance of the engine and if needed adjust the engine, creating a newer version of the product. Also, servitization can be seen as a consequence of the reprogrammable nature as well. Manufactures can be responsible for observing the digital twin, making adjustments, or reprogramming the digital twin when needed and they can offer this as an extra service.
Digital trace making.
Another characteristic that can be observed, is the fact that digital twin technologies leave digital traces. These traces can be used by engineers for example, when a machine malfunctions to go back and check the traces of the digital twin, to diagnose where the problem occurred. These diagnoses can in the future also be used by the manufacturer of these machines, to improve their designs so that these same malfunctions will occur less often in the future.
Modularity.
In the sense of the manufacturing industry, modularity can be described as the design and customization of products and production modules. By adding modularity to the manufacturing models, manufacturers gain the ability to tweak models and machines. Digital twin technology enables manufacturers to track the machines that are used and notice possible areas of improvement in the machines. When these machines are made modular, by using digital twin technology, manufacturers can see which components make the machine perform poorly and replace these with better fitting components to improve the manufacturing process.
Examples.
An example of digital twins is the use of 3D modeling to create digital companions for the physical objects. It can be used to view the status of the actual physical object, which provides a way to project physical objects into the digital world. For example, when sensors collect data from a connected device, the sensor data can be used to update a "digital twin" copy of the device's state in real time. The term "device shadow" is also used for the concept of a digital twin. The digital twin is meant to be an up-to-date and accurate copy of the physical object's properties and states, including shape, position, gesture, status and motion.
A digital twin also can be used for monitoring, diagnostics and prognostics to optimize asset performance and utilization. In this field, sensory data can be combined with historical data, human expertise and fleet and simulation learning to improve the outcome of prognostics. Therefore, complex prognostics and intelligent maintenance system platforms can use digital twins in finding the root cause of issues and improve productivity.
Digital twins of autonomous vehicles and their sensor suite embedded in a traffic and environment simulation have also been proposed as a means to overcome the significant development, testing and validation challenges for the automotive application, in particular when the related algorithms are based on artificial intelligence approaches that require extensive training data and validation data sets.
Industrial use cases.
Manufacturing industry.
The physical manufacturing objects are virtualized and represented as digital twin models (avatars) seamlessly and closely integrated in both the physical and cyber spaces. Physical objects and twin models interact in a mutually beneficial manner.
The digital twin is disrupting the entire product lifecycle management (PLM), from design, to manufacturing, to service and operations. Nowadays, PLM is very time-consuming in terms of efficiency, manufacturing, intelligence, service phases and sustainability in product design. A digital twin can merge the product physical and virtual space. The digital twin enables companies to have a digital footprint of all of their products, from design to development and throughout the entire product life cycle. Broadly speaking, industries with manufacturing business are highly disrupted by digital twins. In the manufacturing process, the digital twin is like a virtual replica of the near-time occurrences in the factory. Thousands of sensors are being placed throughout the physical manufacturing process, all collecting data from different dimensions, such as environmental conditions, behavioural characteristics of the machine and work that is being performed. All this data is continuously communicating and collected by the digital twin.
Due to the Internet of Things, digital twins have become more affordable and could drive the future of the manufacturing industry. A benefit for engineers lies in real-world usage of products that are virtually being designed by the digital twin. Advanced ways of product and asset maintenance and management come within reach as there is a digital twin of the real 'thing' with real-time capabilities.
Digital twins offer a great amount of business potential by predicting the future instead of analyzing the past of the manufacturing process. The representation of reality created by digital twins allows manufacturers to evolve towards ex-ante business practices. The future of manufacturing drives on the following four aspects: modularity, autonomy, connectivity and digital twin. As there is an increasing digitalization in the stages of a manufacturing process, opportunities are opening up to achieve a higher productivity. This starts with modularity and leading to higher effectiveness in the production system. Furthermore, autonomy enables the production system to respond to unexpected events in an efficient and intelligent way. Lastly, connectivity like the Internet of Things, makes the closing of the digitalization loop possible, by then allowing the following cycle of product design and promotion to be optimized for higher performance. This may lead to increase in customer satisfaction and loyalty when products can determine a problem before actually breaking down. Furthermore, as storage and computing costs are becoming less expensive, the ways in which digital twins are used are expanding. Implementation challenges such as data integration, organizational or compliance challenges can hinder the implementation of Digital Twins and its benefits.
Urban planning and construction industry.
Geographic digital twins have been popularised in urban planning practice, given the increasing appetite for digital technology in the Smart Cities movement. These digital twins are often proposed in the form of interactive platforms to capture and display real-time 3D and 4D spatial data in order to model urban environments (cities) and the data feeds within them.
Visualization technologies such as augmented reality (AR) systems are being used as both collaborative tools for design and planning in the built environment integrating data feeds from embedded sensors in cities and API services to form digital twins. For example, AR can be used to create augmented reality maps, buildings, and data feeds projected onto tabletops for collaborative viewing by built environment professionals.
In the built environment, partly through the adoption of building information modeling (BIM) processes, planning, design, construction, and operation and maintenance activities are increasingly being digitised, and digital twins of built assets are seen as a logical extension - at an individual asset level and at a national level. In the United Kingdom in November 2018, for example, the Centre for Digital Built Britain published "The Gemini Principles", outlining principles to guide development of a "national digital twin".
One of the earliest examples of a working 'digital twin' was achieved in 1996 during construction of the Heathrow Express facilities at Heathrow Airport's Terminal 1. Consultant Mott MacDonald and BIM pioneer Jonathan Ingram connected movement sensors in the cofferdam and boreholes to the digital object-model to display movements in the model. A digital grouting object was made to monitor the effects of pumping grout into the earth to stabilise ground movements.
Digital twins have also been proposed as a method to reduce the need for visual inspections of buildings and infrastructure after earthquakes by using unmanned vehicles to gather data to be added to a virtual model of the affected area.
Healthcare industry.
Healthcare is recognized as an industry being disrupted by the digital twin technology. The concept of digital twin in the healthcare industry was originally proposed and first used in product or equipment prognostics. With a digital twin, lives can be improved in terms of medical health, sports and education by taking a more data-driven approach to healthcare. The availability of technologies makes it possible to build personalized models for patients, continuously adjustable based on tracked health and lifestyle parameters. This can ultimately lead to a virtual patient, with detailed description of the healthy state of an individual patient and not only on previous records. Furthermore, the digital twin enables individual's records to be compared to the population in order to easier find patterns with great detail. The biggest benefit of the digital twin on the healthcare industry is the fact that healthcare can be tailored to anticipate on the responses of individual patients. Digital twins will not only lead to better resolutions when defining the health of an individual patient but also change the expected image of a healthy patient. Previously, 'healthy' was seen as the absence of disease indications. Now, 'healthy' patients can be compared to the rest of the population in order to really define healthy. However, the emergence of the digital twin in healthcare also brings some downsides. The digital twin may lead to inequality, as the technology might not be accessible for everyone by widening the gap between the rich and poor. Furthermore, the digital twin will identify patterns in a population which may lead to discrimination.
Automotive industry.
The automobile industry has been improved by digital twin technology. Digital twins in the automobile industry are implemented by using existing data in order to facilitate processes and reduce marginal costs. Currently, automobile designers expand the existing physical materiality by incorporating software-based digital abilities. A specific example of digital twin technology in the automotive industry is where automotive engineers use digital twin technology in combination with the firm's analytical tool in order to analyze how a specific car is driven. In doing so, they can suggest incorporating new features in the car that can reduce car accidents on the road, which was previously not possible in such a short time frame. Digital twins can be built for not just individual vehicles but also the whole mobility system, where humans (e.g., drivers, passengers, pedestrians), vehicles (e.g., connected vehicles, connected and automated vehicles), and traffics (e.g., traffic networks, traffic infrastructures) can seek guidance from their digital twins deployed on edge/cloud servers to actuate real-time decisions.


Artificial intelligence in industry

Industrial artificial intelligence, or industrial AI, usually refers to the application of artificial intelligence to industry. Unlike general artificial intelligence which is a frontier research discipline to build computerized systems that perform tasks requiring human intelligence, industrial AI is more concerned with the application of such technologies to address industrial pain-points for customer value creation, productivity improvement, cost reduction, site optimization, predictive analysis and insight discovery. Although in a dystopian vision of AI applications, intelligent machines may take away jobs of humans and cause social and ethical issues, industry in general holds a more positive view of AI and sees this transformation of economy unstoppable and expects huge business opportunities in this process.
History.
The concept of artificial intelligence was initially proposed in the 1940s, and the idea of improving productivity and gaining insights through smart analytics and modelling is not new. Artificial Intelligence and Knowledge-Based systems have been an active research branch of artificial intelligence for the entire product life cycle for product design, production planning, distribution, and field services. E-manufacturing systems and e-factories did not use the term “AI,” but they scale up modeling of engineering systems to enable complete integration of elements in the manufacturing eco-system for smart operation management.
Recently, to accelerate leadership in AI initiative, the US government launched an official website AI.gov to highlight its priorities in the AI space. There are several reasons for the recent popularity of industrial AI: More affordable sensors and the automated process of data acquisition; More powerful computation capability of computers to perform more complex tasks at a faster speed with lower cost; Faster connectivity infrastructure and more accessible cloud services for data management and computing power outsourcing.
Categories.
Technology alone never creates any business value if the problems in industry are not well studied. The major categories which industrial AI may contribute to include; product and service innovation, process improvement, and insight discovery.
Cloud Foundry service platforms widely embed the artificial intelligent technologies. Cybermanufacturing systems also apply predictive analytics and cyber-physical modeling to address the gap between production and machine health for optimized productivity.
Product applications for user value creation.
Industrial AI can be embedded to existing products or services to make them more effective, reliable, safer, and to enhance their longevity. The automotive industry, for example, uses computer vision to avoid accidents and enable vehicles to stay in lane, facilitating safer driving. In manufacturing, one example is the prediction of blade life for self-aware band saw machines, so that users will be able to rely on evidence of degradation rather than experience, which is safer, will extend blade life, and build up blade usage profile to help blade selection.
Process applications for productivity improvement.
Automation is one of the major aspects in process applications of industrial AI. With the help of AI, the scope and pace of automation have been fundamentally changed. AI technologies boost the performance and expand the capability of conventional AI applications. An example is the collaborative robots. Collaborative robotic arms are able to learn the motion and path demonstrated by human operators and perform the same task. AI also automates the process that used to require human participation. An example is the Hong Kong subway, where an AI program decides the distribution and job scheduling of engineers with more efficiency and reliability than human counterparts do.
Another aspect of process applications is the modeling large-scale systems. Cybermanufacturing systems are defined as a manufacturing service system that is networked and resilient to faults by evidence-based modeling and data-driven deep learning. Such a system deals with large and usually geographically distributed assets, which is hard to be modeled via conventional individual-asset physics-based model. With machine learning and optimization algorithms, a bottom-up framework considering machine health can leverage large samples of assets and automate the operation management, spare part inventory planning, and maintenance scheduling process.
Insight applications for knowledge discovery.
Industrial AI can also be used for knowledge discovery by identifying insights in engineering systems. In aviation and aeronautics, AI has been playing a vital role in many critical areas, one of which is safety assurance and root cause. NASA is trying to proactively manage risks to aircraft safety by analyzing flight numeric data and text reports in parallel to not only detect anomalies but also relate it to the causal factors. This mined insight of why certain faults happen in the past will shed light on predictions of similar incidents in the future and prevent problems before they occur.
Predictive and preventive maintenance through data-driven machine learning is also critical in cost reduction for industrial applications. Prognostics and health management (PHM) programs capture the opportunities at the shop floor by modeling equipment health degradation.
Challenges.
The challenges of industrial AI to unlock the value lies in the transformation of raw data to intelligent predictions for rapid decision-making. In general, there are four major challenges in realizing industrial AI: data, speed, fidelity, and interpretability.
Engineering systems now generate a lot of data and modern industry is indeed a big data environment. However, industrial data usually is structured, but may be low-quality.
Production process happens fast and the equipment and work piece can be expensive, the AI applications need to be applied in real-time to be able to detect anomalies immediately to avoid waste and other consequences. Cloud-based solutions can be powerful and fast, but they still would not fit certain computation efficiency requirements. Edge computing may be a better choice in such scenario.
Unlike consumer-faced AI recommendations systems which have a high tolerance for false positives and negatives, even a very low rate of false positives or negatives rate may cost the total credibility of AI systems. Industrial AI applications are usually dealing with critical issues related to safety, reliability, and operations. Any failure in predictions could incur a negative economic and/or safety impact on the users and discourage them to rely on AI systems.
Besides prediction accuracy and performance fidelity, the industrial AI systems must also go beyond prediction results and give root cause analysis for anomalies. This requires that during development, data scientists need to work with domain experts and include domain know-how into the modeling process, and have the model adaptively learn and accumulate such insights as knowledge.


Flexure

A flexure is a flexible element (or combination of elements) engineered to be compliant in specific degrees of freedom. Flexures are a design feature used by design engineers (usually mechanical engineers) for providing adjustment or compliance in a design.
Flexure types.
Most compound flexure designs are composed of 3 fundamental types of flexure:
Since single flexure features are limited both in travel capability and degrees of freedom available, compound flexure systems are designed using combinations of these component features. Using compound flexures, complex motion profiles with specific degrees of freedom and relatively long travel distances are possible.
Design aspects.
In the field of precision engineering (especially high-precision motion control), flexures have several key advantages. High precision alignment tasks might not be possible when friction or stiction are present. Additionally, conventional bearings or linear slides often exhibit positioning hysteresis due to backlash and friction. Flexures are able to achieve much lower resolution limits (in some cases measured in the nanometer scale), because they depend on bending and/or torsion of flexible elements, rather than surface interaction of many parts (as with a ball bearing). This makes flexures a critical design feature used in optical instrumentation such as interferometers.
Due to their mode of action, flexures are used for limited range motions and cannot replace long-travel or continuous-rotation adjustments. Additionally, special care must be taken to design the flexure to avoid material yielding or fatigue, both of which are potential failure modes in a flexure design.


Jockey wheel

A jockey wheel is a wheel-based mechanical system used for steering or guidance, either:
On trailers.
A jockey wheel for vehicular use is a retractable adjustable-height wheel used on the front of trailers (or caravans) with either a single axle (two running wheels) or more close-coupled axles at or near the centre of gravity whereby without additional support, the trailer would not remain level. The jockey wheel is close to the towing hitch and has a built-in screw jack to enable the trailer nose to be lifted over the tow ball of a car or other powered vehicle. The screw jack can then be used to lower the trailer nose onto the tow ball. Once securely attached to the towing vehicle, the jockey wheel's jacking action is fully retracted for stowage. The jockey wheel can also be unclamped and lifted as far as possible to give the greatest ground clearance before reclamping prior to a journey being made.
Jockey wheels incorporate a castor action, permitting travel in any direction while handling a trailer while it is not attached to a vehicle.
On bicycle dérailleurs.
Although variations exist, dérailleurs change the cog or sprocket used on a bicycle's cogset and the jockey wheels take up slack in the bike chain as it is fed from one of the front chainrings. The jockey wheels are held in a cage. This cage holds two guide pulleys that locate the chain, almost always in a vertically positioned S-shaped pattern (an S in reverse when viewed from the bike's drive side). The pulleys are known collectively as the jockey wheels or jockey pulleys - the guide pulley is at the top of the pairing (closest to the sprockets) and the tension pulley is at the bottom.


Rotational molding

Rotational molding (BrE: moulding) involves a heated mold which is filled with a charge or shot weight of the material. It is then slowly rotated (usually around two perpendicular axes), causing the softened material to disperse and stick to the walls of the mold forming a hollow part. In order to form an even thickness throughout the part, the mold rotates at all times during the heating phase, and then continues to rotate during the cooling phase to avoid sagging or deformation. The process was applied to plastics in the 1950s but in the early years was little used because it was a slow process restricted to a small number of plastics. Over time, improvements in process control and developments with plastic powders have resulted in increased use.
Rotocasting (also known as rotacasting), by comparison, uses self-curing or UV-curable resins (as opposed to thermoplastics) in an unheated mould, but shares slow rotational speeds in common with rotational molding. This kind of rotocasting should not be confused with centrifugal casting.
History.
In 1855 a patent taken out by R. Peters in Britain documented the first use of a rotating mechanism producing “two centrifugal motions at right angles to each other” by means of beveled gearing, and heat. This rotational molding process was used to create artillery shells and other hollow vessels, the main purpose of which was to create consistency in wall thickness and density. In a U.S. patent in 1905, F.A. Voelke described a method including a polymer for the production of articles using paraffin wax. Development led to G.S. Baker's and G.W. Perks' process of producing hollow chocolate Easter eggs in 1910. Rotational molding had developed further when R.J. Powell made mention of the commonly used ratio of 4:1 between major and minor axes of rotation at slow rotation speeds. His patent covered this process for molding hollow objects from plaster of Paris in the 1920s. These early methods using different materials directed the advances in the way rotational molding is used today with plastics.
Plastics were introduced to the rotational molding process in the early 1950s. One of the first applications was to manufacture doll heads. The machinery was made of an E Blue box-oven machine, inspired by a General Motors rear axle, powered by an external electric motor and heated by floor-mounted gas burners. The mold was made of electroformed nickel-copper and the plastic was a liquid polyvinyl chloride (PVC) plastisol. The cooling method consisted of placing the mold into cold water. This process of rotational molding led to the creation of other plastic toys. As demand for and popularity of this process increased, it was used to create other products such as road cones, marine buoys, and car armrests. This popularity led to the development of larger machinery. A new system of heating was also created, going from the original direct gas jets to the current indirect high velocity air system. In Europe during the 1960s the Engel process was developed. This allowed large hollow containers to be manufactured in low-density polyethylene. The cooling method consisted of turning off the burners and allowing the plastic to harden while still rocking in the mold.
In 1976, the Association of Rotational Moulders (ARM) was started in Chicago as a worldwide trade association. The main objective of this association is to increase awareness of the rotational molding technology and process.
In the 1980s, new plastics, such as polycarbonate, polyester, and nylon, were introduced to rotational molding. This has led to new uses for this process, such as the creation of fuel tanks and industrial moldings. The research that has been done since the late 1980s at Queen's University Belfast has led to the development of more precise monitoring and control of the cooling processes based on their development of the “Rotolog system”.
Equipment and tooling.
Rotational molding machines are made in a wide range of sizes. They normally consist of molds, an oven, a cooling chamber, and mold spindles. The spindles are mounted on a rotating axis, which provides a uniform coating of the plastic inside each mold.
Molds (or tooling) are either fabricated from welded sheet steel or cast. The fabrication method is often driven by part size and complexity; most intricate parts are likely made with cast tooling. Molds are typically manufactured from stainless steel or aluminum. Aluminum molds are usually much thicker than equivalent steel molds, as it is a softer metal. This thickness does not much affect cycle times because aluminum's thermal conductivity is many times greater than steel's. Owing to the need to develop a model prior to casting, cast molds tend to have additional costs associated with the manufacturing of the tooling, whereas fabricated steel or aluminum molds, particularly when used for less complex parts, are less expensive. However, some molds contain both aluminum and steel. This allows for variable thicknesses in the walls of the product. While this process is not as precise as injection molding, it does provide the designer with more options. The aluminum addition to the steel provides more heat capacity, causing the melt-flow to stay in a fluid state for a longer period.
Standard setup and equipment for rotational molding.
Normally all rotation molding systems include molds, oven, cooling chamber and mold spindles. The molds are used to create the part, and are typically made of aluminium. The quality and finish of the product is directly related to the quality of the mold being used. The oven is used to heat the part while also rotating the part to form it as desired. The cooling chamber is where the part is placed until it cools, and the spindles are mounted to rotate and provide a uniform coat of plastic inside each mold.
Rotational molding machines.
Rock and roll machine.
This is a specialized machine designed mainly to produce long, narrow parts. Some are of the clamshell type, having one arm, but there are also shuttle-type rock and roll machines, with two arms. Each arm rotates or rolls the mold 360 degrees in one direction and at the same time tips and rocks the mold 45 degrees above or below horizontal in the other direction. Newer machines use forced hot air to heat the mold. These machines are best for large parts that have a large length-to-width ratio. Because of the smaller heating chambers, there is a saving in heating costs compared to biaxial machines.
Clamshell machine.
This is a single-arm rotational molding machine. The arm is usually supported by other arms on both ends. The clamshell machine heats and cools the mold in the same chamber. It takes up less space than equivalent shuttle and swing arm rotational molders. It is low in cost compared to the size of products made. It is available in smaller scales for schools interested in prototyping and for high quality models. More than one mold can be attached to the single arm.
Vertical or up & over rotational machine.
The loading and unloading area is at the front of the machine between the heating and cooling areas. These machines vary in size between small to medium compared to other rotational machines. Vertical rotational molding machines are energy-efficient, owing to the compactness of their heating and cooling chambers. These machines have the same (or similar) capabilities as the horizontal carousel multi-arm machines, but take up much less space.
Shuttle machine.
Most shuttle machines have two arms that move the molds back and forth between the heating chamber and cooling station. The arms are independent of each other and they turn the molds biaxially. In some cases, the shuttle machine has only one arm. This machine moves the mold in a linear direction in and out of heating and cooling chambers. It is low in cost for the size of product produced and the footprint is kept to a minimum compared to other types of machines. It is also available in smaller scale for schools and prototyping.
Swing arm machine.
The swing-arm machine can have up to four arms, with a biaxial movement. Each arm is independent from each other as it is not necessary to operate all arms at the same time. Each arm is mounted on a corner of the oven and swings in and out of the oven. On some swing-arm machines, a pair of arms is mounted on the same corner, so that a four-arm machine has two pivot points. These machines are very useful for companies that have long cooling cycles or require a lot of time to demold parts, compared to the cook time. It is much easier to schedule maintenance work or try to run a new mold without interrupting production on the other arms of the machine.
Carousel machine.
This is one of the most common biaxial machines in the industry. It can have up to four arms and six stations and comes in a wide range of sizes. The machine comes in two different models, fixed and independent. A fixed-arm carousel consists of three fixed arms that must move together. One arm will be in the heating chamber while another is in the cooling chamber and the third in the loading/reloading area. The fixed-arm carousel works well when identical cycle times are used for each arm. The independent-arm carousel machine is available with three or four arms that can move independently. This allows for different-size molds, with different cycle times and thickness needs.
Production process.
The rotational molding process is a high-temperature, low-pressure plastic-forming process that uses heat and biaxial rotation (i.e., angular rotation on two axes) to produce hollow, one-piece parts. Critics of the process point to its long cycle times—only one or two cycles an hour can typically occur, as opposed to other processes such as injection molding, where parts can be made in a few seconds. The process does have distinct advantages. Manufacturing large, hollow parts such as oil tanks is much easier by rotational molding than any other method. Rotational molds are much cheaper than other types of mold. Very little material is wasted using this process, and excess material can often be reused, making it a very economically and environmentally viable manufacturing process.
The rotational molding process consists of four distinct phases:
Recent improvements.
Until recently, the process largely relied on both trial and error and the experience of the operator to determine when the part should be removed from the oven and when it was cool enough to be removed from the mold. Technology has improved in recent years, allowing the air temperature in the mold to be monitored and removing much of the guesswork from the process.
Much current research is into reducing the cycle time, as well as improving part quality. The most promising area is in mold pressurization. It is well known that applying a small amount of pressure internally to the mold at the correct point in the heating phase accelerates coalescence of the polymer particles during the melting, producing a part with fewer bubbles in less time than at atmospheric pressure. This pressure delays the separation of the part from the mold wall due to shrinkage during the cooling phase, aiding cooling of the part. The main drawback to this is the danger to the operator of explosion of a pressurized part. This has prevented adoption of mold pressurization on a large scale by rotomolding manufacturers.
Mold release agents.
A good mold release agent (MRA) will allow the material to be removed quickly and effectively. Mold releases can reduce cycle times, defects, and browning of finished product. There are a number of mold release types available; they can be categorized as follows:
Materials.
More than 80% of all the material used is from the polyethylene family: crosslinked polyethylene (PEX), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and regrind. Other compounds are polyvinyl chloride (PVC) plastisols, nylons, and polypropylene.
Order of materials most commonly used by industry:
These materials are also occasionally used (not in order of most used):
Natural materials.
Recently it has become possible to use natural materials in the molding process. Through the use of real sands and stone chip, sandstone composite can be created which is 80% natural non-processed material.
Rotational molding of plaster is used to produce hollow statuettes.
Chocolate is rotationally molded to form hollow treats.
Products.
Designers can select the best material for their application, including materials that meet U.S. Food and Drug Administration (FDA) requirements. Additives for weather resistance, flame retardation, or static elimination can be incorporated.
Inserts, graphics, threads, handles, minor undercuts, flat surfaces without draft angles, or fine surface detail can be part of the design. Designs can also be multi-wall, either hollow or foam filled.
Products that can be manufactured using rotational molding include storage tanks, furniture, road signs and bollards, planters, pet houses, toys, bins and refuse containers, doll parts, road cones, footballs, helmets, canoes, rowing boats, tornado shelters, kayak hulls, underground cellars for vine and vegetables storage and playground slides. The process is also used to make highly specialised products, including UN-approved containers for the transportation of nuclear fissile materials, anti-piracy ship protectors, seals for inflatable oxygen masks and lightweight components for the aerospace industry.
Design considerations.
Designing for rotational molding.
Another consideration is in the draft angles. These are required to remove the piece from the mold. On the outside walls, a draft angle of 1° may work (assuming no rough surface or holes). On inside walls, such as the inside of a boat hull, a draft angle of 5° may be required. This is due to shrinkage and possible part warping.
Another consideration is of structural support ribs. While solid ribs may be desirable and achievable in injection molding and other processes, a hollow rib is the best solution in rotational molding. A solid rib may be achieved byinserting a finished piece in the mold, but this adds cost.
Rotational molding excels at producing hollow parts. However, care must be taken when this is done. When the depth of the recess is greater than the width there may be problems with even heating and cooling. Additionally, enough room must be left between the parallel walls to allow for the melt-flow to move properly throughout the mold. Otherwise webbing may occur. A desirable parallel wall scenario would have a gap at least three times the nominal wall thickness, with five times the nominal wall thickness being optimal. Sharp corners for parallel walls must also be considered. With angles of less than 45° bridging, webbing, and voids may occur.
Material limitations and considerations.
Another consideration is the melt-flow of materials. Certain materials, such as nylon, will require larger radii than other materials. The stiffness of the set material may be a factor. More structural and strengthening measures may be required when a flimsy material is used.
Wall thickness.
One benefit of rotational molding is the ability to experiment, particularly with wall thicknesses. Cost is entirely dependent on wall thickness, with thicker walls being costlier and more time-consuming to produce. While the wall can have nearly any thickness, designers must remember that the thicker the wall, the more material and time will be required, increasing costs. In some cases, the plastics may degrade owing to extended periods at high temperature. Different materials have different thermal conductivity, meaning they require different times in the heating chamber and cooling chamber. Ideally, the part will be tested to use the minimum thickness required for the application. This minimum will then be established as a nominal thickness.
For the designer, while variable thicknesses are possible, a process called stop rotation is required. This process is limited in that only one side of the mold may be thicker than the others. After the mold is rotated and all the surfaces are sufficiently coated with the melt-flow, the rotation stops and the melt-flow is allowed to pool at the bottom of the mold cavity.
Wall thickness is important for corner radii as well. Large outside radii are preferable to small radii. Large inside radii are also preferable to small inside radii. This allows for a more even flow of material and a more even wall thickness. However, an outside corner is generally stronger than an inside corner.
Process: advantages, limitations, and material requirements.
Advantages.
Rotational molding offers design advantages over other molding processes. With proper design, parts assembled from several pieces can be molded as one part, eliminating high fabrication costs. The process also has inherent design strengths, such as consistent wall thickness and strong outside corners that are virtually stress-free. For additional strength, reinforcing ribs can be designed into the part. Along with being designed into the part, they can be added to the mold.
The ability to add prefinished pieces to the mold alone is a large advantage. Metal threads, internal pipes and structures, and even different colored plastics can all be added to the mold prior to the addition of plastic pellets. However, care must be taken to ensure that minimal shrinkage while cooling will not damage the part. This shrinking allows for mild undercuts and negates the need for ejection mechanisms (for most pieces).
Rotational molding can be used as a feasible alternative to blow molding with products such as plastic bottles and cylindrical containers. This substitution is efficient on only a smaller scale, as blow-molding's efficiency depends on large runs.
Another advantage lies in the molds themselves. Since they require less tooling, they can be manufactured and put into production much more quickly than other molding processes. This is especially true for complex parts, which may require large amounts of tooling for other molding processes. Rotational molding is also the process of choice for short runs and rush deliveries. The molds can be swapped quickly or different colors can be used without purging the mold. With other processes, purging may be required to swap colors.
Due to the uniform thicknesses achieved, large stretched sections are nonexistent, which makes large thin panels possible (although warping may occur). Also, there is little flow of plastic (stretching) but rather a placing of the material within the part. These thin walls also limit cost and production time.
Another cost advantage with rotational molding is the minimal amount of material wasted in production. There are no sprues or runners (as in injection molding), and no off-cuts or pinch-off scrap (as in blow molding). What material is wasted, as scrap or from failed part testing, can usually be recycled.
Limitations.
Rotation-molded parts are subject to restrictions that are different from those of other plastic processes. As it is a low-pressure process, sometimes designers face hard-to-reach areas in the mold. Good-quality powder may help overcome some situations, but usually the designers have to keep in mind that it is not possible to make sharp threads that would be possible with injection molding. Some products based on polyethylene can be put in the mold before it is charged with the main material. This can help to avoid holes that otherwise would appear in some areas. This could also be achieved using molds with movable sections.
Another limitation lies in the molds themselves. Unlike other processes in which only the product needs to be cooled before being removed, with rotational molding the entire mold must be cooled. While water-cooling processes are possible, there is still a large down time of the mold, increasing both financial and environmental costs. Some plastics will degrade with the long heating cycles or in the process of turning them into a powder to be melted.
The stages of heating and cooling involve transfer of heat first from the hot medium to the polymer material and next from it to the cooling environment. In both cases, the process of heat transfer occurs in an unsteady regime; therefore, its kinetics attracts the greatest interest in considering these steps. In the heating stage, the heat taken from the hot gas is absorbed both by the mold and the polymer material. The rig for rotational molding usually has a relatively small wall thickness and is manufactured from metals with a high thermal conductivity (aluminum, steel). As a rule, the mold transfers much more heat than plastic can absorb; therefore, the mold temperature must vary linearly. The rotational velocity in rotational molding is rather low (4 to 20 rpm). As a result, in the first stages of the heating cycle, the charged material remains as a powder layer at the bottom of the mold. The most convenient way of changing the cycle is by applying PU sheets in hot rolled forms.
Material requirements.
Owing to the nature of the process, materials selection must take into account the following: