3D concrete printing

3D concrete printing, or simply concrete printing, refers to digital fabrication processes for cementitious materials based on one of several different 3D printing technologies. 3D printed concrete eliminates the need for formwork, reducing material waste and allowing for greater geometric freedom in complex structures. With recent developments in mix design and 3D printing technology over the last decade, 3D concrete printing has grown exponentially since its emergence in the 1990s. Architectural and structural applications of 3D-printed concrete include the production of building blocks, building modules, street furniture, pedestrian bridges, and low-rise residential structures.
History.
Automating building processes has been an area of research in architecture and civil engineering since the 20th century. The earliest approaches focused on automating masonry. In 1904, a patent for a brick-laying machine was granted to John Thomas in the US. By the 1960s, the technology developed significantly and functional equipment, such as the Motor-Mason, were in use on building sites.
At the same time, automating concrete construction processes was also being developed. Slip forming, a widely used technique today for building vertical concrete cores for high-rise buildings, was developed in the early 20th century for building silos and grain elevators. The concept was pioneered by James MacDonald, of MacDonald Engineering Chicago, and published by Milko S. Ketchum in an illustrated book: "The Design of Walls, Bins, and Grain Elevators" in 1907. Later, MacDonald published a scientific paper: "Moving Forms for Reinforced Concrete Storage Bins" in 1911. Finally, on 24 May 1917, MacDonald was granted a US patent for a device to move and elevate a concrete form in a vertical plane.
Innovations in the automation of concreting processes continued throughout the 20th century. 3D printing processes were first developed in the 1980s for photopolymers and thermoplastics. For some time, 3D printing technology was limited to high value adding sectors such as aerospace and biomedical industries due to the high cost of materials. However, as the knowledge base for 3D printing grew, new additive manufacturing processes were developed for other materials, including for concrete. 3D printed concrete technology originated from Rensselaer Polytechnic Institute (RPI) in New York when Joseph Pegna first applied additive manufacturing to concrete in 1997. This experiment was just a proof of concept, but Pegna recognized the developing robotics industry and saw it as an opportunity to automate the construction process, while also decreasing costs and waste production. Pegna's research would later become the basis for binder jetting, or powder based 3D concrete printing.
In 1998, Behrohk Khoshnevis at the University of Southern California developed Contour Crafting, which was the first layered extrusion device for concrete. The system used a computer controlled crane to automate the pouring process and was capable of creating smooth contour surfaces. Khoshnevis initially designed this system to serve as rapid home construction for natural disaster recovery, and he claimed that the system could complete a home in a single day. With innovations in materials, mix design, and printing technology, researchers and engineers have since expanded on these two printing techniques, which will be discussed further in the following section.
Construction methods.
A number of different approaches have been demonstrated to date, which include on-site and off-site fabrication of building elements or entire buildings, using industrial robots, systems, and tethered autonomous vehicles (see section on 3D Printers). Demonstrations of construction 3D printing technologies have included fabrication of housing, building elements (cladding, structural panels, and columns), bridges, civil infrastructure, artificial reefs, follies, and sculptures. Three different construction methods are currently used in 3D concrete printing: binder jetting, robotic shotcrete, and layered material extrusion.
Binder jetting.
Binder jet 3D printing, also known as powder bed and binder 3D printing, was originally developed at the Massachusetts Institute of Technology for activating starch or gypsum powder with water as binder, before Joseph Pegna applied the system to concrete. In binder jetting, a print head selectively deposits a liquid binder on a powdered substrate, layer by layer. The layer height typically varies between 0.2 and 2 mm and determines both the speed and the level of detail in the finished part. Post-processing steps are necessary in binder-jetting once the layered fabrication is complete. First, the unconsolidated powder needs to be removed mechanically, using brushes and vacuum tubes. Additional curing steps may also be necessary in ovens with controlled humidity and temperature or micro-waves. Finally, coatings may also be applied on the surface to consolidate small surface features or to improve the surface quality of the part. Typical materials used for coatings are polyester or epoxy resin.
3D concrete printing with binder jetting technologies has been demonstrated at large scale by Enrico Dini with D-Shape. D-Shape relies on a non-hydraulic Sorel cement that is based on sand activated with magnesium oxide in the powder bed and a liquid magnesium chloride solution as binder. The technology has mainly been used to create furniture, such as a coffee table and the Root Chair designed by KOL/MAC LLC Architecture + Design in 2009. Furthermore, D-Shape produced large architectural parts, such as the 3 × 3 × 3 m Radiolaria pavilion designed by Shiro Studio in 2008, the Ferreri House for the Triennale di Milano in 2010, and a twelve-metre-long footbridge designed by Acciona in Madrid, in 2017.
Another exponent of binder-jet 3D concrete printing is California-based firm Emerging Objects. For their Bloom pavilion built in 2015, the company used an iron oxide-free cement and organic binder. While it is unclear if there is any cement hydration involved in the process, the project is often cited among other binder-jet 3D concrete printing projects due to the use of cement in the powder bed. Unlike the structures of D-Shape, which were fabricated in one piece, Emerging Objects fabricated 840 small building blocks that were stacked to create the 3.6 × 3.6 × 2.7 m structure.
Advantages and limitations.
Compared to other 3D printing methods for architectural applications, binder jetting allows for a higher degree of geometric freedom, including the possibility to create unsupported cantilevers or overhangs and hollow parts. Unlike other 3D printing processes that require auxiliary support structures, binder jetting relies on the bed of unbonded powder to ensure continuous support for consecutive layers during fabrication.
Typically, in binder jet 3D printing, the left-over powder can be reused for future parts. However, the recyclability of the cement and aggregate powder is problematic due to the exposure to ambient humidity, which can trigger the hydration process. Therefore, binder jet 3D printing is not suitable for on-site construction.
Layered extrusion 3D printing.
Concrete layered extrusion 3D printing involves a numerically controlled nozzle that precisely extrudes a cementitious paste layer by layer. Layers are generally between 5 mm and a few centimeters in thickness. The extrusion nozzle may be accompanied by an automatic troweling tool that flattens the 3D-printed layers and covers the grooves at the interlayer interfaces, resulting in a smooth concrete surface. Additional automation steps have been proposed for the integration in one fabrication step of modular steel reinforcement bars or integrated building services, such as plumbing or electrical conduits. For this process, process planning and deposition speed are critical parameters that influence the material's stiffening and hardening rate.
Layered extrusion 3D concrete printing is most commonly used in on-site construction, and is accompanied by large scale 3D printers (see section on 3D Printers). The technology has seen a growing interest recently, with numerous universities, start-ups, and prominent established construction companies developing dedicated hardware, concrete mixes, and automation setups for concrete extrusion 3D printing. Applications include bridges, columns, walls, floor slabs, street furniture, water tanks, and entire buildings, both in prefabrication or in-situ setups.
Advantages and limitations.
Unlike conventional concrete casting and spraying, layered extrusion 3D printing needs no formworks. This is a significant advantage considering the fact that formworks in concrete construction can account for 50-80% of the resources, more than raw materials, reinforcement, and labour combined. The main challenges of layered concrete extrusion are the set on demand rheology of concrete, the integration of reinforcement, and the formation of cold joints at the interface between consecutive layers.
Slip forming.
Robotic slip-forming, a process developed at ETH Zürich under the name Smart Dynamic Casting, is sometimes included in the family of concrete 3D printing processes, together with layered extrusion and binder-jetting. The process loosely fits the definition of 3D printing, due to its additive nature, material being slowly extruded through an actuated mould that can vary its section. However, unlike the other 3D printing processes, slip forming is a continuous process, and not discrete or layer-based, and therefore it is more closely related to formative processes such as casting and extrusion.
Technology.
3D Printers for Concrete.
There are a few main categories of robots that are used for 3D concrete printing, which depends on the application, scale of the project, and printing technique. All construction 3D printers generally consist of a support structure and a printer head with a nozzle that extrudes the concrete. Printers are usually used in tandem with modelling software that uploads the building plans directly to the printer.
Printer Parameters.
In addition to printer type, specific printer parameters significantly impact the final performance of 3D printed concrete and must be carefully selected when planning for 3D printing construction. These parameters can simply be broken down into print head design and print speed.
Print Head Design.
The print head must be selected so that the concrete mix can smoothly pass through the nozzle and create the bonding effect between each layer, while also initiating the solidification process. Similar to printer selection, nozzle shapes and sizes vary depending on the application. 3D printed concrete samples from nozzles with rectangular holes typically have higher strength than those printed with circular nozzles, because there are fewer gaps between each printed layer. However, circular nozzles are more adept for printing complex geometries. For samples printed from the same nozzle type, mechanical properties are improved when a larger nozzle is used.
The height of the print head is the height of the nozzle relative to the printing platform. This parameter affects the surface quality between layers including bond strength, and must be precisely adjusted. A print head that is set too high will reduce the bond strength between layers, causing an unstable shape. A nozzle too close to the printing surface may interfere with the printing process and place additional loads on the concrete. Research proposes a print height equal to the width of the nozzle.
Print Speed.
The speed at which the print head is set also influences the bonding strength. Increasing the nozzle speed generally decreases the adhesive strength, as the concrete has little time to set into place. However, taking too long to print successive layers reduces interlayer bonding, so a balance must be established that accounts for strength without premature collapse. Other factors that influence the quality of 3D printed concrete include the pumps and controls used to monitor the printer, as well the concrete mix design (See section on Mix Design).
3D Printer Suppliers.
3D concrete printing technology has grown exponentially over the last decade, and is expected to continue to grow as researchers learn more about the software, hardware, and construction capabilities of these printers. Below are some notable companies and 3D printers that are used globally:
Mix Design.
Critical Mix Properties.
For 3D printed concrete, buildability and extrudability are two of the most critical design properties for a mix. Extrudability is the mixture's ability to pass through nozzles in the printing head, while buildability is the capacity to support additional layers. These properties are governed by the consistency, cohesiveness, and stability of the mixture, which stem from the mix design and selected materials. For both properties, a balance must be met between stiffness and workability. A stiff mix will increase strength, but decrease flow rate and print speed, potentially clogging the printer head. Conversely, decreasing the stiffness too much may increase workability and extrudability at the expense of strength and buildability.
Since concrete is printed in layers, layers must sufficiently bond to each other to allow for proper curing and full-strength capacity. Significant research has been conducted to create an optimal mix for 3D printing, although there are no current industry standards. However, the use of supplementary cementitious materials (SCMs) such as metakaolin, fly ash, silica fume, and superplasticizers are common in all 3D printed concrete mixtures (See section on Admixtures).
Cementitious Materials.
Cementitious materials are integral to any concrete mix design. These materials serve as the binder that holds the mix together, as they chemically react with water to undergo the curing process. Portland cement is the most common material in construction for both 3D printed and traditional concrete applications due to its low cost and widespread availability. However, it's high setting time and low bonding ability are disadvantageous for 3D printed applications. Therefore, polymers and other admixtures are often added to reduce shrinkage and improve adhesion. Some of these polymers include rubber, mixed sand aggregates, carbon-sulfur polymers, and geopolymers, which also have added benefits of crack repair and resistance.
One alternative is sulfoaluminate cement which can be mixed with Portland Cement to quicken the hydration process and help develop early concrete strength after placement. While the setting time of Portland Cement is about half an hour, the setting time for sulfoaluminate cement is just six minutes. Therefore, higher strength can be achieved in a much shorter time period, increasing buildability.
Aggregates.
Aggregate content and selection are just as important as the selected cementitious materials when it comes to concrete mix design. In particular, particle size has a significant effect on 3D printed concrete mixes. Particle sizes that are too large may block the nozzle of the 3D printer, while aggregates that are too small decrease the strength of the mix and can cause cracking. A rule of thumb for mix design is that the maximum aggregate particle size should be less than 1/10 of the nozzle diameter to ensure smooth extrusion.
Several studies have been conducted to examine the influence of aggregate size on mechanical properties for 3D printed concrete. It was found that increasing coarse aggregate improves volumetric stability of concrete and decreases hydration heat and shrinkage, which were common problems in early 3D printed concrete mixes. The use of coarse aggregate also increases concrete deposition rate and printhead speed, which can increase printing efficiency and productivity. Therefore, the printed structure achieves greater stability and strength, as observed by Ivanova and Mechtcherine. There is a limit to coarse aggregate content and size, as the challenge of controlling rheology become apparent. Natural aggregates such as sand and gravel are preferred as they require less energy to produce compared to artificial aggregates, but aggregate selection can be limited by regional deposits.
Admixtures.
Admixtures include any materials outside of water, aggregates, and cementitious materials, that affect the concrete mix properties. Especially in 3D printed concrete, these admixtures are critical to balancing buildability, workability, and extrudability. Fly ash is the main admixture for high performance 3D printed concrete, as it improves working performance and durability. However, large amounts of flyash can lead to slower development of strength and buildability, which is why it is often mixed with other admixtures like clay, to retain shape stability.
Silica fume is another common admixture for 3D printed concrete mixes, as it increases the initial strength of printed concrete as well as flexural strength once the concrete cures. The main advantage of silica fume is that its small particles fill in the void spaces around the larger aggregates, which improves bonding performance with the cement binder. This also helps optimize the particle size distribution of the mix, which increases yield stress and buildability.
Mechanical Properties.
As with standard concrete mixes, mixes for 3D printed concrete are typically tested for their compressive and flexural strength. These mechanical properties are highly dependent on the mix design, and can be improved by adding admixtures such as the ones described in the above section. For a mix containing ordinary Portland Cement, fly ash, silica fume, and fine glass aggregates, the compressive strength is around 36 to 57 MPa, which is comparable to the compressive strength of normal weight concrete. High performance concrete strengths of over 100 MPa have also been achieved by using superplasticizers and additional chemicals, but these mixes are more energy intensive to produce.
For 3D printed concrete, the structural properties are largely influenced by the interlayer bonding performance. Increasing the print speed and printhead height can reduce the interlayer bond strength, while adding a mortar between the layers can improve this strength. Particular, a resin mortar composed of black charcoal, sulfur, and sand has been found to be effective.
Concrete Suppliers for 3D Printing.
Since there are no standards set for 3D printing concrete mix design, companies often pursue their own research and development if they decide to offer 3D printing as a construction service. Below are some notable companies that have successfully implemented 3D concrete printing into their scope of services.
Notable Projects and Applications.
Due to challenges of reinforcement and limitations in printing technology, applications of 3D printed concrete have been mostly limited to small scale projects, including models and residential homes, as opposed to large commercial buildings. There are, however, some notable projects around the world that demonstrate the potential of 3D printed concrete.
ICON: 3D Printed Homes.
ICON is creating a community of 100 3D printed homes in Georgetown, Texas. Reservations will begin in 2023 with starting prices in the mid $400,000. The fleet of Vulcan printers can produce eight different floor plans of 3 to 4 bedrooms and 2 to 3 baths. A concrete feeding system known as Magma supplies the Vulcan printer with Icon's developed concrete mix known as Lavacrete, which can adjust for site weather conditions and supply read-to-print concrete automatically. The 90 to 200m2 3D printed homes take around five to seven days to print, compared to a timber frame which would take up to 16 weeks in the same area.
ICON also completed a project in March 2020 for seven 3D printed homes in Austin, Texas. Each 400 ft2 home was printed in just 27 hours using ICON's Vulcan printer. The first residents moved into the homes in 2020 and are estimated to house 480 of the city's homeless, about 40% of the city's homeless population.
Habitat for Humanity: Affordable Homes Fast.
In 2021, Habitat for Humanity, the world's largest non-profit home builder organization, built two 3D printed homes in Williamsburg, Virginia, and Tempe, Arizona. The Virginia home was 1,200 ft2 and printed in just 28 hours with a COBOD 3D printer, which was about four weeks faster than standard construction. The organization estimated that the 3D printed concrete walls saved about 15% per square foot in building costs. The 1,738 ft2 home in Arizona was constructed in the summer: a time where construction typically halts due to the extreme heat. 80% of the home was constructed using 3D printing including the interior and exterior walls, while the remainder, such as the roof, was constructing using traditional methods. Habitat for Humanity hopes that 3D printed homes can be a solution for affordable housing as well as labor shortages in extreme climates and environments.
PERI: Project Milestone.
The first 3D printed residential building in Germany was constructed in September 2020 by PERI, using COBOD's BOD2 printer and Heidelberg Cement's concrete mixture. 24 concrete elements were printed at a facility and then transported to the site for assembly. The printer created 1 m2 of wall every 5 minutes, completing the 160m2 home by November 2020. Only two operators were required to print the walls, which included water placement, electricity, and pipe connections.
Nijmegen, Netherlands: Pedestrian Bridge.
In 2021, the Dutch city of Nijmegen revealed the world's longest 3D printed concrete pedestrian bridge, spanning 29 meters. It was estimated that 3D printed saved about 50% in materials because concrete was only placed where structural strength was required. 3D printed bridge components were manufactured by BAM and Weber Beamix offsite, where it was then transported and assembled on-site. The previous record holder for the longest 3D printed concrete bridge was 26 meters, constructed by Tsinghua University in Shanghai.
Economic Impacts.
In terms of cost and economics, one advantage of 3D printed concrete is that it does not require formwork, which is used to form the mold for conventional concrete pouring. Formwork can account up to 50% of total concrete construction due to material and labor costs. However, there are costs associated with machinery including the print head nozzles and supplemental monitoring devices. In addition, 3D printed concrete mixtures often differ from conventional concrete with additions of nano-clay, nano-silica, and other chemical admixtures that aid the extrusion process.
There are indirect economic benefits from 3D printed concrete in terms of productivity. The construction sector is often highly traditional and for the most part, processes have remained similar over the past decades. This is in large part because current processes are still effective in many construction applications. For example, a study by Garcia de Soto compared a robotically fabricated and conventionally constructed wall assembly with different degrees of complexity and found that that conventional construction outperformed robotic fabrication for simpler walls, while the robot was more productive as geometric complexity increased. There was no additional cost due to robotic fabrication and for both cases, material production was the driving factor for cost, as opposed to construction procedures.
Environmental Impacts.
The environmental impact of 3D printed concrete is heavily dependent on the processes and materials used for a given project. 3D printed concrete has the potential to reduce material in the production of concrete due to the elimination of formwork, but the specialized admixtures and required technology may have just as much of an impact on the environment as conventional concrete construction. A cradle to grave life-cycle assessment (LCA) comparing the environmental impact of a conventionally constructed concrete wall with a 3D printed concrete wall revealed that the 3D printed alternative only reduced environmental effects when no reinforcement was used. The LCA impacts of global warming potential, acidification potential, eutrophication potential, and smog formation potential were used to measure environmental impacts. Once reinforcement was introduced to the 3D printed concrete structure, these impacts were greater than conventional construction methods, specifically for global warming and smog formation potential.
Another LCA conducted a similar study comparing conventional and 3D printed concrete walls but varied the complexity of the structure. It was found that as the complexity of the structure increased, the 3D printed method how a lower environmental impact. This was mostly due to the ability of 3D printed concrete to achieve complex forms while saving building materials in terms of formwork and concrete volume. Overall, the environmental impact of 3D printed concrete is influenced by the structure's design and how well the engineer can optimize material usage. On a material basis, the environmental impacts are similar to that of conventional concrete, as a cement binder is still required. However, the streamlined construction process that comes with 3D printing decreases material waste and onsite emissions.
Challenges and Limitations.
There are several limitations that prevent 3D concrete printing from being widely adopted throughout the construction industry. First, the material palette that can be used for 3D printed concrete is limited, particularly due to nozzle extrusion and the deposition process of concrete layers, which introduces the challenge of premature collapsing. Therefore, research on material properties and developing high quality cementitious materials that comply with both structural concrete codes 3D printing applications is a current area of focus. Due to the sensitivity of a concrete mix, a change cement type, aggregate, or admixture will impact concrete properties and behavior.
Current building codes consider concrete has a homogenous material when in the reality, concrete is anisotropic. This anisotropy is further exposed with printed layers, so new methods for estimating deformations and cracking must be developed. In addition, current material testing for concrete consists of cylindrical specimens in accordance with ASTM C39. There is currently no systematic or theoretical basis for 3D printed concrete, especially when it comes to standard testing.
Current 3D printed projects have been limited to model prototyping and low-rise, large area buildings as opposed to high-rise commercial buildings because of restrictions in 3D printer technology. Printers need to be compatible with the height of the building, so additional research in 3D printer stability and design is required. There are also challenges with reinforcement in 3D concrete printing, which is required for taller structures. See reinforcement for 3D concrete printing for more details.
Research and Development.
Pioneering research on the topic of 3D concrete printing is conducted at the ETH Zurich, Loughborough University, Swinburne University of Technology, Eindhoven University of Technology, and the Institute for Advanced Architecture of Catalonia, among many other institutions.
Conferences.
Due to the increased interest in 3D concrete printing both from industry and academia, a number of conferences have started internationally. Two industry-focused international conferences were organized in February and November 2017 by 3DPrinthused in Copenhagen. Subsequently, the biannual Digital Concrete academic conference was organized at the ETH Zürich in 2018, the Eindhoven institute of Technology in 2020 and at the University of Loughborough in 2022. A parallel series of recurring conferences, focusing on the Asia-Pacific region, was organized at the Swinburne University of Technology in 2018, Tianjin University in 2019, and Shanghai Tongji and Hebei universities in 2020.
Related topics.
Concrete printing can be used directly to produce the final part, or indirectly, to produce formwork in which concrete is cast or sprayed.
3D-printed formworks address some of the major challenges of 3D concrete printing. Reinforcement bars can be integrated conventionally, and the conventionally cast or sprayed concrete complies with building codes. Additionally, the surface quality of concrete is significantly better than in 3D concrete printing. To achieve a smooth surface, the 3D-printed formworks can be coated or polished.
3D-printed concrete as formwork.
3D concrete printing with layered extrusion has been used to produce stay-in-place formworks for casting concrete. In this approach, a thin shell, consisting of one or two 3D-printed contours is produced in a first step, either in a prefabrication plant or directly in situ. Subsequently, reinforcement cages are installed and secured in position. Finally, concrete is cast inside the shell, either in one go, or in several steps to prevent the build up of hydrostatic pressure in the lower sections of the formwork.
For structural calculations, the 3D-printed shell is usually ignored, and only the cast concrete is considered load-bearing. However, the 3D-printed shell may be considered for the necessary concrete reinforcement cover that protects the steel from corrosion.
3D-printed formworks for concrete.
Alternatively, 3D printing with non-cementitious materials can be employed for the production of formworks for concrete. Extrusion printing with clay, foam, wax, and polymers, as well as binder jetting with sand and stereolithography have been used for the fabrication of formworks for architectural concrete components.


OScar (Danish automobile)

OScar is a limited production sports car produced in Denmark from 1983 to 1986. The car was built by Ole Sommer, a prominent automobile importer and dealer.
Ole Sommer.
Ole Sommer was a Danish importer of automobiles and car enthusiast. He found business success importing Volvo, Renault and Jaguar cars into Denmark. Sommer had an interest in producing a car in Denmark and in the 1970s built a few cars called Joker which were a type of beach buggy based on a Volvo 140. In the 1980s, Sommer set his sights on building a sports car. Sommer later established an automotive museum. He died in 2018.
OScar.
The car was named OScar for "Ole Sommer car". Sommer imported fiberglass body shells based on the AC Cobra from BRA in the United Kingdom. Unlike the multitude of other manufactures who created AC Cobra replicas or imitations, Sommer wanted to use Volvo underpinnings.
The car was built on a custom frame. The engines available were from Volvo: they were straight-four turbocharged Redblocks of the B19 and B23 variety. Customers were offered the option of up-tuning the engine for more than the standard horsepower from the Volvo engine.
OScar featured a Volvo front axle and steering assembly from a 140 and a rear axle from a 240. Electronic components were lifted from a 340. The transmission was a Volvo M46 four-speed. Remaining components were hand-made at Sommer's facility including the exceptionally large 70 liter fuel tank. Instrumentation was custom produced by VDO in Germany.
Sommer had envisaged a larger scale production than the 20 units that were produced. Automotive regulations, including crash testing, made it difficult to sell the car. Volvo also refused to let Sommer use his Volvo dealer network to sell the car.


Manufacturing clause

The Manufacturing clause is a clause contained in copyright legislation requiring that as a condition of obtaining copyright, all copies of a work must be printed or otherwise produced domestically, from plates set domestically, rather than imported. In the United States, a manufacturing clause was included in the International Copyright Act of 1891, which allowed certain non-resident aliens to obtain U.S. copyrights for the first time. The clause initially covered books, maps, photographs, and lithographs, and was subsequently extended to periodicals as well. Its extension to all other media was proposed in the 1897 Treloar Copyright Bill, which failed in committee. The manufacturing clause did not expire until 1986, keeping the United States out of the Berne Convention until 1989.


Ball differential

A ball differential is a type of differential typically used on radio-controlled cars. It differs from a geared differential by using several small ball bearings rotating between two plates, instead of bevel gears.
History.
The first ball differential for Radio-controlled Cars was designed by Cecil Schumacher, a British motor sport engineer working at Cosworth and founder/owner of his eponymous model brand. Although a patent was applied for, it was denied as the idea had already been implemented into a lawn mower. Radio-controlled cars were still a new application for the ball differential and Schumacher is generally considered the modern day inventor of the concept. Such was the popularity of the ball differential, originally applied in 1/12 on-road cars, that he formed his eponymous company.
To this date ball differentials remain very popular in the radio-controlled car market. They are used on almost every 1/12 on-road, scale touring car (although the sealed gear differential is gaining popularity in this class) and produced by many manufacturers. In these classes they are regarded as the industry standard. Schumacher Racing Products even use ball differentials on their nitro truck range, these however use strong materials and larger and harder ball bearings.
Basic principles.
Radio-controlled car manufacturers use the same basic design Schumacher created in the 1980s. The main part of the differential is a drive gear (or pulley in a belt transmission) with multiple holes cut through it, following its outside diameter. These holes are slightly larger than the width of the ball bearings, so that the balls, commonly around 2 mm diameter in a model car, sit inside the holes of the gear/pulley.
On either side of the gear are the thrust washers. The thrust washers are pushed against the ball bearings inside the gear by Belleville washers. On one side of the gear is an adjusting collar, which allows for adjustments in the amount of slip allowed by the differential. A thrust bearing (or thrust race), on the opposite side of the gear, is used to stop the differential from loosening the retaining screw holding the output cups, used to attach the differential to the axle, onto the differential.
As the screw is tightened it pushes the Belleville and thrust washers onto the gear/pulley. This creates contact between the washers and ball bearings inside of the gear/pulley. The friction created by the contact between the washers and ball bearings is, aided by grease (commonly silicone grease), designed so that as one washer moves, the ball bearings rotate.
As the washer on one side of the gear rotates, the rotation of the balls causes the other washer to rotate in the opposite direction, because any rotating ball will have opposite sides moving in opposite directions .
Differential movement is achieved through the process of the thrust washers rotating with the ball bearings. The retaining screw is designed so the differential can be easily adjusted by tightening or loosening the screw, consequently changing force. This makes the differential more adjustable than geared differentials, but there is a lower limit since the drive is by friction so there is always some limited slip action.
There are several types of balls used in this type of differential. Some of the most common ball materials used by high end racers are ceramic and tungsten based. The advantage to something like ceramic based balls is that they are much harder, and have a longer life expectancy. Oftentimes when using less hard materials, the balls will "flat spot" causing a semi locked direction of the ball. This causes the differential to not turn with a smooth feeling and leaves it with an overall "gritty" feeling.


Jig (tool)

A jig is a type of custom-made tool used to control the location and/or motion of parts or other tools.
Description.
A jig's primary purpose is to provide repeatability, accuracy, and interchangeability in the manufacturing of products.
An example of a jig is when a key is duplicated; the original is used as a jig so the new key can have the same path as the old one. Since the advent of automation and computer numerical controlled (CNC) machines, jigs are often not required because the tool path is digitally programmed and stored in memory. Jigs may be made for reforming plastics.
Jigs or templates have been known long before the industrial age. There are many types of jigs, and each one is custom-tailored to do a specific job.
Drill jig.
A "drill jig" is a type of jig that expedites repetitive hole center location on multiple interchangeable parts by acting as a template to guide the twist drill or other boring device into the precise location of each intended hole center. In metalworking practice, typically a hardened drill bushing lines each hole on the jig plate to keep the tool from damaging the jig.
Drill jigs started falling into disuse with the invention of the jig borer.
Since the widespread penetration of the manufacturing industry by CNC machine tools, in which servo controls are capable of moving the tool to the correct location automatically, the need for drill jigs (and for the jobs of the drill press operators who used them) is much less than it used to be.
PCB jig.
Printed circuit board (PCB) jigs are used to test PCBs. They have a dump board inside the jig which can find faults in the PCBs.
Jewelry jig.
A jig used in making jewelry, a specific type of jig, is a plate or open frame for holding work and helping to shape jewelry components made out of wire or small sheets of metal. A jig in the jewelry making application is used to help establish a pattern for use in shaping the wire or sheets of metal. In the jewelry application, the shaping of the metal is done by hand or with simple hand tools like a hammer.


Compatible ink

Compatible ink (or compatible toner) is manufactured by third-party manufacturers and is designed to work in designated printers without infringing on patents of printer manufacturers. Compatible inks and toners may come in a variety of packaging including sealed plastic wraps or taped plastic wraps. Regardless of packaging, compatible products are generally priced lower than original equipment manufacturer (OEM) brand inks and toners.
While there has been considerable debate and litigation involving the ink and toner patents of printer manufacturers, third-party manufacturers continue to thrive. Manufacturers of compatible ink and toner products currently control about 25% the ink and toner market well over $8 Billion annually.
Types.
Compatible ink is manufactured for several types of machines including fax machines, laser printers, inkjet printers, multifunction printers, and copiers. Aside from compatible products, three other sources of consumables are also available to supply these machines, including OEM brand ink and toner, remanufactured toner and ink cartridges, and refilled ink and toner cartridges. Compatible ink manufacturers differentiate their product by using all new parts, whereas other ink replacements recycle used OEM parts. Compatible ink and toner products tend to offer greater value than original, genuine OEM ink and toner cartridges. Reducing cost for the end user, ink and toner manufactured by third-party manufacturers is classified as compatible when consisting of new parts for a third party printer.
Comparison of performance, quality and reliability.
The performance of a printer cartridge needs to be measured by parameters like:
A comparison between OEM and compatible cartridges for a specific printer needs to take into account the above parameters. For example, a remanufactured cartridge may for example be purchased cheaper, but may not print out as many useful pages. Reliability and consistency associated with an OEM cartridge may be more important than price, for example, when printing output for important business.
One independent test in 2004 on using a compatible ink for one type of printer showed little or no difference in quality between the compatible and OEM products.
All types of compatible ink cartridges are different and vary from supplier to supplier. This is due to the type of ink in the printer, the chips (or no chip) on the cartridge and the actual manufacture of the cartridge itself.
In terms of comparisons with suppliers, prices, quality and comparisons with original oem cartridges. This can vary also by manufacturer and printer. Some compatible cartridges will work perfectly in some printers.


Linishing

Linishing is the process of using grinding or belt sanding techniques to improve the flatness, smoothness and uniformity of a surface and its finish. The process takes multiple stages, and a finer abrasive surface is typically used each time. Abrasive brushes and linishing belts are typically used, the latter being a machine similar to a belt sander used for large surfaces. Large linishing belts are used in large-scale industrial linishing processes. Hand tools similar to linishing belts but much smaller and more suitable for small surfaces are also used.


List of capacitor manufacturers

A capacitor is a passive device on a circuit board that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. This is a list of capacitor manufacturers (past and present) and their headquarters location.
Sources.
[[Category:Capacitor manufacturers| ]]
[[Category:Lists of manufacturers|Capacitors]]


Frequent deliveries

Frequent deliveries are a largely ignored but powerful way of leveling apparent demand within a supply chain and thereby reducing Mura. What is perhaps not so obvious is that this will reduce inventory levels and thereby assist progress along the Lean journey at the same time. The historical focus upon carrying full loads, sometimes of only one product, reduces the unit cost of transport but has sometimes hidden the true costs associated with achieving those transport discounts. It is also possible to gain some of these benefits by 'faking' frequent deliveries at the supply site.
Principles.
Reducing production lot size and raising delivery frequency.
If we{who?|date=January 2019]} model this idea using a factory that produces three products (Triangles, Circles and Squares) and is making a regular daily delivery to its customer at the end of each day then we can represent this as below.
Stock builds up during the day until the factory has completed the production campaign of three products each of which is produced in a lot of four. After each lot of four a line-changeover happens, there are in fact three as we must include the one before the first production lot. Stock builds here to a maximum of twelve units. If the number of changeovers were doubled to six then the stock levels would remain the same all the stock is still on site until the shipment.
The customer is receiving a mix of products that it is likely that they consume (or their in-stock equivalent) during, say, the next day. If the customer consumes the provided products during the day then their stock level will decrease by twelve over the day.
So if the customer will agree to receive half the daily shipment of each product halfway through the day and the second half at the original time of end of day and we reduce lot sizes by a factor of two the factory schedule would look like this.
We now see that the benefits of the lot size reduction in the stock levels, both at the customer and at the supplying factory. Stock at both locations has been reduced by six. A possible downside for the factory is that it now has twice the changeovers (See Single-Minute Exchange of Die (SMED)).
If we take this to the extreme where the factory now has a changeover after every unit of production (single piece flow) and where shipments occur after every campaign (every product has been made) then the factory has this situation.
Now stock levels, again at the customer and supplier, are down to three from twelve. To achieve this cost effectively the changeovers must be very quick.
Just raising delivery frequency.
So starting from the same original situation.
The factory chooses to just make the deliveries more frequent but not change production lot size, and to keep some extra stock so that deliveries can be exactly as in the model where lot sizes were changed as well.
Here, although an extra stock of two is constantly being held it can be seen that the deliveries still reduce the holding by six giving a net benefit of four at the factory and six at the customer. This is without changing the production schedule.
If, again, this is taken to the extreme where deliveries are going to be made of one unit of each product and stock keeping adjusted to make this possible then this situation is seen.
Here, although an extra stock of three is constantly being held it can be seen that the deliveries still reduce the holding by nine giving a net benefit of six at the factory and nine at the customer. This is still without changing the production schedule.
Summary.
So from this example it can be seen that just increasing delivery frequency reduces the stock held in the system. This is no surprise to those in the context of station to station within a factory. It does seem to surprise many when used in the context of supplier to customer. The summary of this argument is in the table below.
Implementation.
So now the question is how to achieve this more frequent delivery. Well in fact many of the benefits within the factory can be achieved by 'faking' frequent deliveries while discussions with the customer about actual delivery frequencies takes place.
Faking frequent deliveries.
The removal of items in the factory from the 'manufacturing system' will trigger the resupply that we wish to smooth via kanban or other signals. The frequent deliveries will provide a smoother sequence of smaller resupply signals. So by 'faking it' what is meant is that the actual delivery schedule will be de-coupled from the resupply triggers in the factory.
This can be done by marking a position on the floor, say a rectangular outline of perhaps the same size as the truck, in the loading bay and designating it to be a specific planned delivery or part of one. Let's call that outline a 'virtual truck'. Clearly if all the items for the delivery were now loaded into the virtual truck then the impact on demand signals into the factory would be the same as a real truck load. The secret here is to schedule a steady flow of items from the factory into the virtual truck so that demand appears as flat as possible. Obviously this may seem like 'smoke and mirrors' since the goods are still actually in the loading bay. The importance is that demand and supply are now decoupled. So whilst a real truck can still be loaded at the required speed, from the virtual truck, the signals for resupply passing via kanbans etc. back into the factory have created a smooth demand. This method can also be used to give early warning to the factory that it is falling behind the required schedule if it is to have all goods ready for shipment when the real truck arrives.
The downside of this trick is that there are now two movements of the goods, one to the virtual truck and one from it to the real truck.
Actual frequent deliveries.
Since these need to meet agreement with the customer these will be less flexible than the 'virtual truck's' unless they are part of an internal process. Between 1982 and 1990 Toyota reorganised its service and crash parts business and as part of that it established Local Distribution Centres (LDCs) in each metropolitan centre. It also encouraged dealers to work intensively with customers so that maintenance was scheduled sufficiently in advance that parts requirements could be precisely predicted.
Because the LDCs are so close to the dealers it was possible to establish a 'milk run' which visited every dealer every two hours. So when the service is booked a preliminary order is prepared for the required parts. The day before the scheduled service the customer is called to confirm the service and then a firm order to the LDC is placed for delivery on the next 'milk run'. Finally, when the car arrives for its service it is inspected and any other required parts ordered for delivery with 2–4 hours (the next run). This has resulted in very significant stock reductions throughout the system as the table below illustrates.


Shifting bottleneck heuristic

The Shifting Bottleneck Heuristic is a procedure intended to minimize the time it takes to do work, or specifically, the makespan in a job shop. The makespan is defined as the amount of time, from start to finish, to complete a set of multi-machine jobs where machine order is pre-set for each job. Assuming that the jobs are actually competing for the same resources (machines) then there will always be one or more resources that act as a 'bottleneck' in the processing. This heuristic, or 'rule of thumb' procedure minimises the effect of the bottleneck. The Shifting Bottleneck Heuristic is intended for job shops with a finite number of jobs and a finite number of machines.
Uses.
The Shifting Bottleneck Heuristic is used in manufacturing and service industries that include job shops with constraints on the order that the machines must be used for each job. A good example of a service industry that may use this technique is a hospital. The different areas within a hospital, such as physical examination, x-ray booth, cat scan, or surgery, could all be considered machines for this particular application. A precedence constraint in this context is when one machine must be used before another machine on any given job (or patient). These types of problems with multiple machines are known to be computationally very difficult. The processing time of each job on each machine is given (see chart on right for an example). Job "j" being performed on machine "i" is denoted "ij". It is assumed that each machine can only work on one job at a time. The objective is to determine the schedule that will produce the shortest makespan.
Procedure.
First graph.
The first step is to draw out the precedence constraints in a graphical form called a graph (See Original Drawing picture). Each job originates at the "source", which we will label U on the graph. Each job will finish in a "sink" of jobs, which we will label V on the graph. Each row of nodes in the graph represents a job. Each node on the graph represents a task that is part of the job, the second number confirms the job being performed and the first number indicates what machine is being used for this task. At this point, the initial throughput time of each job should be calculated by adding up the processing times that the job takes on each of the machines (or rows). After the throughput time for each job has been calculated, the makespan for the system is determined by the longest throughput time of any individual job. This assumes no resource conflicts and gives a makespan of 22.
First iteration.
The next step is to determine which resource/machine is currently the bottleneck. This is done by considering the production time, denoted "pij", that each job takes on each machine, the release time of each job on each respective machine, and the due date of each job for each respective machine. The release time, denoted "rij", is determined by adding up the processing times of job "j" on the machines that precede machine "i" in the job order of job "j". The due date, denoted "dij", is determined by subtracting the processing times of job "j" on the machines succeeding the machine "i" in the job order from the makespan. Once all of this is determined, the minimum lateness for each machine needs to be determined. This is accomplished by finding the path for each machine that reduces the maximum lateness seen for all jobs on the respective machine. This can be done using a branch and bound technique for example. It can also be approximated using an other heuristic such as the earliest due date heuristic. Once the maximum lateness is determined for each of the respective machines, the machine with the largest maximum lateness is the bottleneck. If there is no maximum lateness on any of the machines, one can draw all of the machines’ optimal sequences in the job diagram. If there are two machines with the same maximum lateness, either one can be chosen for the bottleneck. All of this work is considered the first iteration.
Once the bottleneck has been determined, the path for the machine needs to be included in the graph of jobs (See Iteration 1 Drawing, where the colored arrows represent disjunctive constraints). These new paths can be considered the disjunctive constraints and they need to be taken into consideration when determining the new makespan. The disjunctive constraints are the machine constraints in our job shop. The new makespan will be the old makespan plus the maximum lateness of the machine determined to be the bottleneck.
Second iteration.
The next step is to perform a new analysis for each of the remaining machines. The differences now are there is a new makespan, and the precedence constraints need to be considered as well as the disjunctive constraints when determining the release date of each job on the machine. The longest path to get from the "source" U to the respective job, coming from comparing the release times of the preceding jobs for disjunctive constraints and precedence constraints, will be the new release date. The due dates will be the time that the given job needs be finished on the respective machine to still have enough time to finish the job on the proceeding machines within the makespan. This is the length of the longest path from the job to the "sink" V. The proceeding jobs are known from the precedence constraints.
Again, determine which machine is the new bottleneck. Add the new disjunctive constraints to the graph (see Iteration 2). This is considered the second iteration. The new makespan is the old makespan plus the maximum lateness from the new bottleneck. Again, if the maximum lateness on all machines is zero then use all the paths for the disjunctive constraints on the drawing and the makespan is still the same as it was before.
Further iterations.
This process is repeated until all machines have been accounted for or the maximum lateness is zero on all respective remaining machines. Each time the process is repeated, it is considered an iteration and all of the disjunctive constraints may be drawn on the job and machine diagram. For our example, the next iteration provided us with zero for the maximum lateness on machines 3 and 4, so their optimal sequences can be included in the drawing (see Iteration 3).
At this point the Shifting Bottleneck Heuristic is complete. The drawing should now include all precedence constraints and all disjunctive constraints. The final makespan is the original makespan plus all of the maximum latenesses from each of the respective bottlenecks. It is the lowest amount of time needed complete all of the jobs given these machine and precedence constraints.
References.
Pinedo, Michael. Planning and Scheduling in Manufacturing and Services. Springer Science+Business Media, LLC. 2005. Pages 87–93. .


Chip formation

Chip formation is part of the process of cutting materials by mechanical means, using tools such as saws, lathes and milling cutters.
The formal study of chip formation was encouraged around World War II and shortly afterwards, with increases in the use of faster and more powerful cutting machines, particularly for metal cutting with the new high speed steel cutters. Pioneering work in this field was carried out by Kivima (1952) and Franz (1958).
Chip formation is usually described according to a three-way model developed by Franz. This model is best known within the field of machine tool design, although it is also used when an application area, such as woodworking, requires a vocabulary to describe chip formation in more detail than is usually attempted.
Chip classification.
The first three chip types are the original characterisation, by Dr. Norman Franz. The type of chip that forms depends on many factors, of both tool and material. In general, main factors are the angle formed by the edge faces of the tool and also the angle at which this is presented to the surface.
Sharpness of the cutting tool does not usually define the "type" of chip, but rather the "quality" of the chip, and the clear distinctions between types. A blunt tool produces a degenerate chip that is large, torn and varies from one means of formation to another, often leaving behind a poor quality surface where this means changes.
Type I chip.
Type I chips form when a material splits "ahead" of the cutting edge, owing to some upwards wedge action of the tool exceeding the "tensile" strength of the material, perpendicular to the surface. They are thus particularly important in fibrous materials, such as wood, where individual fibres are strong but they may be levered apart relatively easily. Type I chips generally form in cutting by tools with shallow cutting angles.
Type I chips may form long, continuous swarf, limited in size only by the length of cut.
This is the idealised chip formation for wood shavings, particularly those produced by a well-tuned plane with a finely adjusted mouth.
Type II chip.
Type II chips form when a shearing force is produced by the wedge of the tool angle. The material fails along a short angled plane, from the apex of the tool edge, diagonally upwards and forwards to the surface. The material deforms along this line, forming an upward curling chip. These chips generally form from intermediate cutting angles.
Type II chips may form in ductile materials, such as metals.
Type II chips may also form long, continuous swarf.
Type III chip.
Type III chips form a compression failure of the material, ahead of a relatively obtuse cutting angle, approaching 90°. In some weak or non-ductile materials this may form an acceptable chip, usually as a fine dust, but often it gives rise instead to a random "snowplough" effect where the waste material is bunched up ahead of the tool but not cleared decisively away as a well-formed chip.
This type of chip is formed by routers. It is also formed by woodworking scrapers, although when properly sharpened and used, these form such a thin Type III chip that it instead appears as a well-formed Type II chip. Their waste chip is thin enough that the compression failure volume is small enough to act as for the well-defined shear plane of the Type II.
Type 0 chip.
This type was characterised later, by William McKenzie (1960).


Characteristic based product configurator

A characteristic-based product configurator is a product configurator extension which uses a set of discrete variables, called characteristics (or features), to define all possible product variations.
Characteristics.
There are two characteristic types:
Constraints.
The range of characteristic-value combinations is reduced by a variety of constraints that define which combinations can, cannot, and must occur alongside each other. These constraints can be reflective of technological or commercial constraints in the real world.
The constraints can represent:
Characteristic filters.
The use of characteristics permits the user to abstract the finished product by describing filter conditions, which describe subsets of product variations using boolean functions on the characteristics:
Closed or open configuration.
Using a characteristic-based configurator, it is possible to define a product variation in two ways:
Applications.
Some examples of applications where using a characteristics-based product configurator may be advantageous are:
Examples.
pCon.planner from EasternGraphics is an OFML-based complex product configurator used for interior design.


Microextrusion

Microextrusion is a microforming extrusion process performed at the submillimeter range. Like extrusion, material is pushed through a die orifice, but the resulting product's cross section can fit through a 1mm square. Several microextrusion processes have been developed since microforming was envisioned in 1990. Forward (ram and billet move in the same direction) and backward (ram and billet move in the opposite direction) microextrusion were first introduced, with forward rod-backward cup and double cup extrusion methods developing later. Regardless of method, one of the greatest challenges of creating a successful microextrusion machine is the manufacture of the die and ram. "The small size of the die and ram, along with the stringent accuracy requirement, needs suitable manufacturing processes." Additionally, as Fu and Chan pointed out in a 2013 state-of-the-art technology review, several issues must still be resolved before microextrusion and other microforming technologies can be implemented more widely, including deformation load and defects, forming system stability, mechanical properties, and other size-related effects on the crystallite (grain) structure and boundaries.
Development and use.
Microextrusion is an outgrowth of microforming, a science that was in its infancy in the early 1990s. In 2002, Engel "et al." expressed that up to that point, only a few research experiments involving micro-deep drawing and extruding processes had been attempted, citing limitations in shearing on billets and difficulties in tool manufacturing and handling. By the mid- to late 2000s, researchers were working on issues such as billet flow, interfacial friction, extrusion force, and size effects, "the deviations from the expected results that occur when the dimension of a workpiece or sample is reduced." Most recently, research into using ultrafine-grained material at higher formation temperatures and applying ultrasonic vibration to the process has pushed the science further. However, before bulk production of microparts such as pins, screws, fasteners, connectors, and sockets using microforming and microextrusion techniques can occur, more research into billet production, transportation, positioning, and ejection are required.
Microextrusion techniques have also been applied to bioceramic and plastic extrusion and the manufacture of components for resorbable and implantable medical devices, from bioresorbable stents to controlled drug release systems.
Microextrusion processes.
Like normal macro-level extrusion, several similar microextrusion processes have been described over the years. The most basic processes were forward (direct) and backward (indirect) microextrusion. The ram (which propels the billet forward) and billet both move in the same direction with forward microextrusion, while in backward microextrusion has the ram and billet moving in opposite directions. These in turn have been applied to specialized applications such as the manufacture of microbillet, brass micropins, microgear shafts, and microcondensers. However, other processes have been applied to microextrusion, including forward rod–backward cup extrusion and double cup (one forward, one backward) extrusion.
Strengths and limitations.
Strengths of microextrusion over other manufacturing processes include its ability to create very complex cross-sections, preserve chemical properties, condition physical properties, and process materials which are delicate or dependent on physical or chemical properties. However, microextrusion has some limitations, though primarily related to the need for improvement of the relatively young process. Dixit and Das described it thus in 2012:
With the scaling down of dimensions and increasing geometric complexity of objects, currently available technologies and systems may not be able to meet the development needs. New measuring devices, principles and instrumentation, tolerance rules, and procedures have to be developed. Materials databases with detailed information on various materials and their properties/interface properties including microstructures and size effect would be very useful for product innovation and process design. More studies are necessary on micro/nanowear and damages/failures of the micromanufacturing tools. The forming limits for different types of materials at the microlevel must be prescribed. More specific considerations must be incorporated into the design of machines that are scaled down for microforming to meet engineering applications and requirements.


Anomatic

Anomatic Corporation manufactures aluminum products, and is a manufacturer of large-quantity aluminum parts for cosmetic companies' packaging including Revlon, Maybelline, Estee Lauder and Mary Kay.
History.
Since 1965, Anomatic has been manufacturing items ranging from consumer products such as MP3 players, cookware, and baseball bats to industrial applications such as heat sinks and aerospace/aviation components.
Product lines.
The company produces anodized aluminum packaging for the personal care, makeup, fragrance, automotive, pharmaceutical, health and beauty industries for clients as well as industrial applications. It is headquartered in New Albany, Ohio with additional US manufacturing locations in Newark, Ohio, Blacklick, Ohio, Naugatuck, Connecticut, and an international facility in Suzhou, China. Anomatic’s services include package design, rapid 3D prototyping, metal forming, anodizing, decorating, assembly, and metallization.
Specializing in high-volume runs, Anomatic is known as the "color experts" for its highly-consistent anodizing process and color matching capabilities. Now vertically-integrated, Anomatic has reinvested to add multiple additional decorative technologies as well as metallization in-house, making the company one of the only metallizing manufacturers in the US to supply the cosmetics industry.
Environmental policies.
Anomatic is committed to being environmentally responsible. The company has implemented a sustainability plan to reduce energy, waste, water and air pollution as well as recycle and reuse materials. In 2010, Anomatic announced the formation of the Sustainability and Environmental Operations Group which works to expand the company’s sustainable and green operations through Lean, Six Sigma and GMP. The company opened its LEED-certified facility in New Albany, Ohio within the International Personal Care and Beauty Campus and moved its headquarters there.


Ball detent

A ball detent is a simple mechanical arrangement used to hold a moving part in a temporarily fixed position relative to another part. Usually the moving parts slide with respect to each other, or one part rotates within the other.
The ball is a single, usually metal sphere, sliding within a bored cylinder, against the pressure of a spring, which pushes the ball against the other part of the mechanism, which carries the detent - which can be as simple as a hole of smaller diameter than the ball. When the hole is in line with the cylinder, the ball is partially pushed into the hole under spring pressure, holding the parts at that position. Additional force applied to the moving parts will compressing the spring, causing the ball to be depressed back into its cylinder, and allowing the parts to move to another position.
Applications.
Ball detents are commonly found in the selector mechanism of a gearbox, holding the selector rods in the correct position to engage the desired gear. Other applications include clutches that slip at a preset torque, and calibrated ball detent mechanisms are typically found in a torque wrench.
Ball detents are one of the mechanisms often used in folding knives to prevent unwanted opening of the blade when carrying.
Ball detents were used in the Curta mechanical calculator to enforce discrete values.
Use in paintball markers.
The term "ball detent" is also used when referring to a mechanism in paintball markers designed to prevent the paintball from rolling out of the firing chamber before being fired. Some designs are similar to those outlined above, with a cartridge utilizing a ball bearing in a bore with spring pressure. The cartridge is installed perpendicular to the barrel bore axis, just ahead of where the ball rests before being fired. Other designs use elastic rubber protrusions that block the ball until it is pushed over it by the bolt. Some designs use precisely calibrated rings or "barrel sizers" that are selected to have a slightly smaller inner diameter than the outer diameter of the paintballs being used. They rely on simple constriction of the bore to prevent paintballs from rolling through them from the force of gravity. When the marker is fired, the air pressure pushes the ball through the bore, causing it to compress enough to pass through. Paintballs have varying diameters depending on a number of factors; this type of ball detent must be sized correctly to avoid compressing the paintball too much, causing it to burst. If too large of a sizer is selected, balls may roll through it.
The cartridge and elastic rubber protrusion type detents are primarily used for open bolt markers, or on closed bolt markers to prevent double feeding (feeding more than one ball when the bolt is open for loading). Closed bolt markers generally use the constriction method to prevent "roll outs", a malfunction where the ball completely rolls out of the barrel, causing no paintball to be fired when the trigger is pulled. A partial roll out is when the ball rolls partially through the barrel, causing reduced velocity.


Rework (electronics)

Rework (or re-work) is the term for the refinishing operation or repair of an electronic printed circuit board (PCB) assembly, usually involving desoldering and re-soldering of surface-mounted electronic components (SMD). Mass processing techniques are not applicable to single device repair or replacement, and specialized manual techniques by expert personnel using appropriate equipment are required to replace defective components; area array packages such as ball grid array (BGA) devices particularly require expertise and appropriate tools. A hot air gun or hot air station is used to heat devices and melt solder, and specialised tools are used to pick up and position often tiny components.
A rework station is a place to do this work—the tools and supplies for this work, typically on a workbench. Other kinds of rework require other tools.
Reasons for rework.
Rework is practiced in many kinds of manufacturing when defective products are found.
For electronics, defects may include:
Process.
The rework may involve several components, which must be worked on one by one without damage to surrounding parts or the PCB itself. All parts not being worked on are protected from heat and damage. Thermal stress on the electronic assembly is kept as low as possible to prevent unnecessary contractions of the board which might cause immediate or future damage.
In the 21st century, almost all soldering is carried out with lead-free solder, both on manufactured assemblies and in rework, to avoid the health and environmental hazards of lead. Where this precaution is not necessary, tin-lead solder melts at a lower temperature and is easier to work with.
Heating a single SMD with a hot-air gun to melt all solder joints between it and the PCB is usually the first step, followed by removing the SMD while the solder is molten. The pad array on the conductor board should then be cleaned of old solder. It is quite easy to remove these residues by heating them to melting temperature. A soldering iron or hot air gun can be used with desoldering braid.
The precise placement of the new unit onto the prepared pad array requires skillful use of a highly accurate vision-alignment system with high resolution and magnification. The smaller the pitch and size of the components, the more precise working must be.
Finally the newly placed SMD is soldered onto the board. Reliable solder joints are facilitated by use of a solder profile which preheats the board, heats all the connections between the unit and the PCB to the melting temperature of the solder used, then properly cools them.
High quality demands or specific designs of SMDs require the precise application of solder paste before positioning and soldering the unit. The surface tension of the molten solder, which is on the board's solder pads, tends to pull the device into precise alignment with the pads if not initially positioned totally correctly.
Reflowing and reballing.
Ball grid arrays (BGA) and chip scale packages (CSA) present special difficulties for testing and rework, as they have many small, closely spaced pads on their underside which are connected to matching pads on the PCB. Connecting pins are not accessible from the top for testing, and cannot be desoldered without heating the whole device to the melting point of solder.
After fabrication of the BGA package, tiny balls of solder are glued to the pads on its underside; during assembly the balled package is placed on the PCB and heated to melt the solder and, all being well, to connect each pad on the device to its mate on the PCB without any extraneous solder bridging between adjacent pads. Bad connections produced during assembly can be detected and the assembly reworked (or scrapped). Imperfect connections of devices which are not themselves faulty, which work for a time and then fail, often triggered by thermal expansion and contraction at operating temperature, are not infrequent.
Assemblies which fail because of bad BGA connections can be repaired either by reflowing, or by removing the device and cleaning it of solder, reballing, and replacing. Devices can be recovered from scrapped assemblies for reuse in the same way.
Reflowing as a rework technique, similar to the manufacturing process of reflow soldering, involves dismantling the equipment to remove the faulty circuit board, pre-heating the whole board in an oven, heating the non-functioning component further to melt the solder, then cooling, following a carefully determined thermal profile, and reassembling, a process which is hoped will repair the bad connection without the need to remove and replace the component. This may or not resolve the problem; and there is a chance that the reflowed board will fail again after some time. For typical devices (PlayStation 3 and Xbox 360) one repair company estimates that the process, if there are no unexpected problems, takes about 80 minutes. On a forum where professional repair people discuss reflowing of laptop computer graphics chips, different contributors cite success rates (no failure within 6 months) of between 60 and 90% for reflowing with professional equipment and techniques, in equipment whose value does not justify complete reballing. Reflowing can be done non-professionally in a domestic oven or with a heat gun. While such methods can cure some problems, the outcome is likely to be less successful than is possible with accurate thermal profiling achieved by an experienced technician using professional equipment.
Reballing involves dismantling, heating the chip until it can be removed from the board, typically with a hot-air gun and vacuum pickup tool, removing the device, removing solder remaining on the device and board, putting new solder balls in place, replacing the original device if there was a poor connection, or using a new one, and heating the device or board to solder it in place. The new balls can be placed via several methods, including:
For the PS3 and Xbox mentioned above, the time is about 120 minutes if all goes well.
Chips are at risk of being damaged by the repeated heating and cooling of reballing, and manufacturers' warranties sometimes do not cover this case. Removing solder with solder wick subjects devices to thermal stress fewer times than using a flowing solder bath. In a test twenty devices were reballed, some several times. Two failed to function, but were restored to full functionality after reballing again. One was subjected to 17 thermal cycles without failing.
Results.
Properly carried out rework restores the functionality of the reworked assembly, and its subsequent lifetime should not significantly be affected. Consequently, where the cost of reworking is less than the value of the assembly, it is widely used in all sectors of the electronic industry. Manufacturer and service providers of communications-technologies, entertainment- and consumer-devices, industrial commodities, automobiles, medical technology, aerospace and other high power electronics rework when necessary.


Shadow board

A shadow board is a type of tool board for organizing a set of tools; the board defines where particular tools should be placed when they are not in use. Shadow boards have the outlines of a work station's tools marked on them, allowing operators to identify quickly which tools are in use or missing. The boards are commonly located near the work station where the tools are used. Shadow boards are often used in the manufacturing environment to improve a facility's lean six sigma capabilities.
Shadow boards reduce time spent looking for tools and also reduce losses. They improve work station safety because tools are replaced safely after use, rather than becoming potential hazards.


Conductive anodic filament

Conductive anodic filament, also called CAF, is a metallic filament that forms from an electrochemical migration process and is known to cause printed circuit board (PCB) failures.
Mechanism.
CAF formation is a process involving the transport of conductive chemistries across a nonmetallic substrate under the influence of an applied electric field. CAF is influenced by electric field strength, temperature (including soldering temperatures), humidity, laminate material, and the presence of manufacturing defects. The occurrence of CAF failures has been primarily driven by the electronics industry pushing for higher density circuit boards and the use of electronics in harsher environments for high reliability applications.
Failure modes and detection.
CAF commonly occurs between adjacent vias (i.e. plated through holes) inside a PCB, as the copper migrates along the glass/resin interface from anode to cathode. CAF failures can manifest as current leakage, intermittent electrical shorts, and even dielectric breakdown between conductors in printed circuit boards. This often makes CAF very difficult to detect, especially when it occurs as an intermittent issue. There are a few things that can be done to isolate the fault location and confirm CAF as a root cause of a failure. If the issue is intermittent then putting the sample of interest under combined temperature-humidity-bias (THB) may help recreate the failure mode. In addition, techniques such as cross sectioning or superconducting quantum interference device (SQUID) can be used to identify the failure.
Considerations and mitigation.
There are several design considerations and mitigation techniques that can be used to reduce the susceptibility to CAF. Certain material selection (i.e. laminate) and design rules (i.e. via spacing) can help reduce CAF risk. Poor adhesion between the resin and glass fibers in the PCB can create a path for CAF to occur. This may depend on parameters of the silane finish applied to the glass fibers, which is used to promote adhesion to the resin. There are also testing standards that can be performed to assess CAF risk. IPC TM-650 2.6.25 provides a test method to assess CAF susceptibility. Additionally, IPC TM-650 2.6.16 provides a pressure vessel test method to rapidly evaluate glass epoxy laminate integrity. This is helpful but it may often be better to use design rules and proper material selection to proactively mitigate the issue.


Lyman filament extruder

 The Lyman filament extruder is a device for making 3-D printer filament suitable for use in 3-D printers like the RepRap. It is named after its developer Hugh Lyman and was the winner of the Desktop Factory Competition.
The goal in the competition was to build an open source filament extruder for less than $250 in components that can take ABS or PLA resin pellets, mix them with colorant, and extrude enough 1.75 mm diameter ± 0.05 mm filament that can be wrapped on a 1 kg spool. The machine must use the Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) license.
The use of DIY filament extruders like the Lyman can significantly reduce the cost of printing with 3-D printers. The Lyman filament extruder was designed to handle pellets, but can also be used to make filament from other sources of plastic such as post-consumer waste like other RecycleBots. Producing plastic filament from recycled plastic has a significant positive environmental impact.


Distributed manufacturing

Distributed manufacturing also known as distributed production, cloud producing, distributed digital manufacturing, and local manufacturing is a form of decentralized manufacturing practiced by enterprises using a network of geographically dispersed manufacturing facilities that are coordinated using information technology. It can also refer to local manufacture via the historic cottage industry model, or manufacturing that takes place in the homes of consumers.
Enterprise.
In enterprise environments, the primary attribute of distributed manufacturing is the ability to create value at geographically dispersed locations. For example, shipping costs could be minimized when products are built geographically close to their intended markets. Also, products manufactured in a number of small facilities distributed over a wide area can be customized with details adapted to individual or regional tastes. Manufacturing components in different physical locations and then managing the supply chain to bring them together for final assembly of a product is also considered a form of distributed manufacturing. Digital networks combined with additive manufacturing allow companies a decentralized and geographically independent distributed production (cloud manufacturing).
Consumer.
Within the maker movement and DIY culture, small scale production by consumers often using peer-to-peer resources is being referred to as distributed manufacturing. Consumers download digital designs from an open design repository website like Youmagine or Thingiverse and produce a product for low costs through a distributed network of 3D printing services such as 3D Hubs, Geomiq. In the most distributed form of distributed manufacturing the consumer becomes a prosumer and manufacturers products at home with an open-source 3-D printer such as the RepRap. In 2013 a desktop 3-D printer could be economically justified as a personal product fabricator and the number of free and open hardware designs were growing exponentially. Today there are millions of open hardware product designs at hundreds of repositories and there is some evidence consumers are 3-D printing to save money. For example, 2017 case studies probed the quality of: (1) six common complex toys; (2) Lego blocks; and (3) the customizability of open source board games and found that all filaments analyzed saved the prosumer over 75% of the cost of commercially available true alternative toys and over 90% for recyclebot filament. Overall, these results indicate a single 3D printing repository, MyMiniFactory, is saving consumers well over $60 million/year in offset purchases of only toys. These 3-D printers can now be used to make sophisticated high-value products like scientific instruments. Similarly, a study in 2022 found that 81% of open source designs provided economic savings and the total savings for the 3D printing community is more than $35 million from downloading only the top 100 products at YouMagine. In general, the savings are largest when compared to conventional products when prosumers use recycled materials in 'distributed recycling and additive manufacturing' (DRAM).
Social change.
Some call attention to the conjunction of commons-based peer production with distributed manufacturing techniques. The self-reinforced fantasy of a system of eternal growth can be overcome with the development of economies of scope, and here, the civil society can play an important role contributing to the raising of the whole productive structure to a higher plateau of more sustainable and customised productivity. Further, it is true that many issues, problems and threats rise due to the large democratization of the means of production, and especially regarding the physical ones. For instance, the recyclability of advanced nanomaterials is still questioned; weapons manufacturing could become easier; not to mention the implications on counterfeiting and on "intellectual property". It might be maintained that in contrast to the industrial paradigm whose competitive dynamics were about economies of scale, commons-based peer production and distributed manufacturing could develop economies of scope. While the advantages of scale rest on cheap global transportation, the economies of scope share infrastructure costs (intangible and tangible productive resources), taking advantage of the capabilities of the fabrication tools. And following Neil Gershenfeld in that “some of the least developed parts of the world need some of the most advanced technologies”, commons-based peer production and distributed manufacturing may offer the necessary tools for thinking globally but act locally in response to certain problems and needs. As well as supporting individual personal manufacturing social and economic benefits are expected to result from the development of local production economies. In particular, the humanitarian and development sector are becoming increasingly interested in how distributed manufacturing can overcome the supply chain challenges of last mile distribution. Further, distributed manufacturing has been proposed as a key element in the Cosmopolitan localism or cosmolocalism framework to reconfigure production by prioritizing socio-ecological well-being over corporate profits, over-production and excess consumption.
Technology.
By localizing manufacturing, distributed manufacturing may enable a balance between two opposite extreme qualities in technology development: Low technology and High tech. This balance is understood as an inclusive middle, a "mid-tech", that may go beyond the two polarities, incorporating them into a higher synthesis. Thus, in such an approach, low-tech and high-tech stop being mutually exclusive. They instead become a dialectic totality. Mid-tech may be abbreviated to “both…and…” instead of “neither…nor…”. Mid-tech combines the efficiency and versatility of digital/automated technology with low-tech's potential for autonomy and resilience.


Fixed position assembly

Fixed position assembly refers to an assembly system or situation in which the product does not move while being assembled, this configuration is usually contrasted in operations management and industrial engineering with assembly lines. Dimensioning this system is very simple: considering CP as productive capacity and T as average assembly time, then N, number of working stations, is given by N=CP*T.


Electrospark deposition

Electrospark deposition is a micro-welding manufacturing process typically used to repair damage to precision or valuable mechanical components such as injection moulding tools. This process may also be referred to as "spark hardening", "electrospark toughening" or "electrospark alloying".


Parting line

A parting line, in industrial casting of molds, is the border line in which draft angles change direction. One can check the parting line in the mould or product which divides the two half, i.e; the core and the cavity of a molded part. It is sometimes a starting point for the mold parting surface. In engineering drawing, a parting line is often abbreviated as PL. ASME's Y14.8 standard specifies a symbol for parting line. Engineering applications (seals, tight running molded parts) that require precision for shape control, call for removal of flashes. Many molders will repair or even replace the mold tooling so that the flash is reduced to an acceptable tolerance or eliminated altogether. Secondary operations to remove parting line flash include hand trimming, vibratory tumbling, media blasting and cryogenic deflashing.


Iron powder

Iron powder has several uses; for example production of magnetic alloys and certain types of steels.
Iron powder is formed as a whole from several other iron particles. The particle sizes vary anywhere from 20-200 μm. The iron properties differ depending on the production method and history of a specific iron powder. There are three types of iron powder classifications: reduced iron powder, atomized powder, and electrolytic iron powder. Each type is used in various applications depending on their properties. There is very little difference in the visual appearances of reduced iron powder and atomized iron powder.
Applications.
Automobiles.
Most iron powders are used for automobile parts.
Other.
Iron powder is also used for the following:


Wire wrapped jewelry

Wire wrapping is one of the oldest techniques for making handmade jewelry. This technique is done with jewelry wire and findings similar to wire (for example, head-pins) to make components. Wire components are then connected to one another using mechanical techniques with no soldering or heating of the wire. Frequently, in this approach, a wire is bent into a loop or other decorative shape and then the wire is wrapped around itself to finish the wire component. This makes the loop or decorative shape permanent. The technique of wrapping wire around itself gives this craft its name of wire wrapping.
History.
Examples of wire and beaded jewelry made using wire wrapping techniques date back to thousands of years BC. The British Museum has samples of jewelry from the Sumerian Dynasty, found in the cemetery of Ur that contain spiraled wire components. This jewelry is dated at approximately 2000 BC. Other samples of jewelry from Ancient Rome show wire wrapped loops (one of the important techniques in making wire wrapped jewelry). This Roman jewelry is dated to approximately 2,000 years ago. In the manufacture of this early jewelry the techniques for soldering did not exist. Later, as the technique for soldering developed, the wire wrapping approach continued because it was an economical and quick way to make jewelry components out of wire.
Wire wrapping techniques are not frequently used for mass-produced jewelry because machines can cast (mold) jewelry components faster, more cheaply, and more precisely. The wire wrapping approach to making jewelry is primarily employed by individuals.
Characteristics.
Wire wrapped jewelry is jewelry made of wire with mechanical connections instead of soldered connections. The key differences between making jewelry by wire wrapping and other approaches to making jewelry are two-fold;
A key element in wire wrapped jewelry is a loop made in wire. Loops are connected to one another to make the mechanical connections between components. A "P" loop is made by bending the wire until it touches the wire again (but this is too crude looking for serious jewelry use). The best-looking loop is the eye loop, with a full circle of wire centered over the stem of wire (like a lollipop).
P loops and eye loops are "open" loops. This means that the loop can be opened mechanically to allow it to connect to another component, which allows it to open too easily when strained. A stronger (and better looking) loop is the closed loop, where the end of the wire is wrapped around the stem of the loop three or four times, so that the loop is permanent and cannot be opened, this is called a "wrapped loop". A connection between two wrapped loops must be performed before the second loop is wrapped closed.
In the simplest example of handmade wire wrapped jewelry, a bead is threaded onto a jewelry making finding called a head–pin. The bead is held in place by the "head" on the head pin. The portion of the head pin coming out of the opposite side of the bead is essentially wire. This wire is bent into a loop using hand tools and the excess wire is cut off. The resulting bead hanging from a loop is called a "bead dangle". To complete a simple earring, the loop in the bead dangle is connected to the loop at the end of an ear wire finding leaving a completed earring.
Tools.
Four tools are essential and several other tools are useful in the construction of wire wrapped jewelry. The basic tools are a flush cutter, round nose pliers, flat nose pliers and chain nose or bent chain nose pliers. A flush cutter is a special type of cutter that leaves one end of the cut wire flush or flat, while the opposite end of the cut wire is sharp or pointed. Round nose pliers are pliers with conical jaws and are used for making loops in wire. Chain nose or bent chain nose pliers have flat smooth jaws and are used for gripping and holding wire and for bending wire. Flat nose pliers are just what the name implies, they are flat on both inside surfaces and are used to keep areas flat or to make 90-degree bends in your wire.
Other useful tools used in making wire wrapped jewelry are nylon jaw pliers, a ruler, step jaw pliers, a pin vise to twist the wire, a chasing hammer, an anvil or bench block, a cup bur, loop closing or bent closing pliers and a jewelry making jig.
Wire.
Wire is available is shapes such as round, square, half-round and patterns, such as flat and pre-twisted. It is also available in a variety of materials. Copper and brass wire are easy to shape and manipulate. Copper wire can be hammered quite thin. Brass wire is a little stiffer than copper, but it can be manipulated very easily. Sterling silver is soft enough to manipulate, but holds its shape well once it has been formed. Gold-filled wire is made by fusing a layer of 12-or 14-karat gold to a supporting material. Silver-filled wire is made in the same manner. The bond between the two materials is permanent.
Wire is measured by diameter, which is indicated by gauge numbers. The lower the gauge, the thicker the wire. A 12- or 14-gauge wire is fairly heavy, but ideal for making bangles and chokers. 10-gauge wire is very thick and stiff, while 26-gauge wire is very fine, almost as thin as hair. This thin wire is well-suited for coiling embellishments. 16-gauge wire is good for making jump rings and links for necklaces and bracelets, and 18-gauge wire is good to use for adding embellishments and making finer links.
Precious metal wire also comes in three hardnesses:
Supplies.
A craftsperson can purchase pre-made components instead of making them. Pre-made components come under the generic name findings. The most important findings used in making jewelry are ear wires, clasps, head pins, and jump rings.