Turning

Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates.
Usually the term "turning" is reserved for the generation of "external" surfaces by this cutting action, whereas this same essential cutting action when applied to "internal" surfaces (holes, of one kind or another) is called "boring". Thus the phrase "turning and boring" categorizes the larger family of processes known as lathing. The cutting of faces on the workpiece, whether with a turning or boring tool, is called "facing", and may be lumped into either category as a subset.
Turning can be done manually, in a traditional form of lathe, which frequently requires continuous supervision by the operator, or by using an automated lathe which does not. Today the most common type of such automation is computer numerical control, better known as CNC. (CNC is also commonly used with many other types of machining besides turning.)
When turning, the workpiece (a piece of relatively rigid material such as wood, metal, plastic, or stone) is rotated and a cutting tool is traversed along 1, 2, or 3 axes of motion to produce precise diameters and depths. Turning can be either on the outside of the cylinder or on the inside (also known as boring) to produce tubular components to various geometries. Although now quite rare, early lathes could even be used to produce complex geometric figures, even the platonic solids; although since the advent of CNC it has become unusual to use non-computerized toolpath control for this purpose.
The turning processes are typically carried out on a lathe, considered to be the oldest of machine tools, and can be of different types such as "straight turning", "taper turning", "profiling" or "external grooving". Those types of turning processes can produce various shapes of materials such as "straight", "conical", "curved", or "grooved" workpieces.
In general, turning uses simple "single-point cutting" tools. Each group of workpiece materials has an optimum set of tool angles that have been developed through the years.
The bits of waste metal from turning operations are known as chips (North America), or swarf (Britain). In some areas they may be known as "turnings".
The tool's axes of movement may be literally a straight line, or they may be along some set of curves or angles, but they are essentially linear (in the non mathematical sense).
A component that is subject to turning operations can be termed as a “Turned Part” or “Machined Component”. Turning operations are carried out on a lathe machine which can be manually or CNC operated.
Turning operations.
Turning specific operations include:
The general process of turning involves rotating a part while a single-point cutting tool is moved parallel to the axis of rotation. Turning can be done on the external surface of the part as well as the internal surface (the process known as boring). The starting material is generally a workpiece generated by other processes such as casting, forging, extrusion, or drawing.
Facing in the context of turning work involves moving the cutting tool at right angles to the axis of rotation of the rotating workpiece. This can be performed by the operation of the cross-slide, if one is fitted, as distinct from the longitudinal feed (turning). It is frequently the first operation performed in the production of the workpiece, and often the last—hence the phrase "ending up".
This process, also called parting off or cutoff, is used to create deep grooves which will remove a completed or part-complete component from its parent stock.
Grooving is like parting, except that grooves are cut to a specific depth instead of severing a completed/part-complete component from the stock. Grooving can be performed on internal and external surfaces, as well as on the face of the part (face grooving or trepanning).
Non-specific operations include:
Lathes.
A lathe is a machine tool used principally for shaping pieces of metal, wood, or other materials by causing the workpiece to be held and rotated by the lathe while a tool bit is advanced into the work causing the cutting action. Lathes can be divided into three types for easy identification: engine lathe, turret lathe, and "special purpose lathes". Some smaller ones are bench mounted and semi-portable. The larger lathes are floor mounted and may require special transportation if they must be moved.
Field and maintenance shops generally use a lathe that can be adapted to many operations and that is not too large to be moved from one work site to another. The engine lathe is ideally suited for this purpose. A trained operator can accomplish more machining jobs with the engine lathe than with any other machine tool. Turret lathes and special purpose lathes are usually used in production or job shops for mass production or specialized parts, while basic engine lathes are usually used for any type of lathe work.
Tooling.
The various angles, shapes, and sizes of a "single-point cutting" tool have direct relation to the resulting surface of a workpiece in machining operations. Different types of angle such as "rake angle", "side rake angle", "cutting-edge angle", "relief angle", "nose radius" exist and may be different with respect to the workpiece. Also, there are many shapes of "single-point cutting" tools, such as "V-shaped" and "Square." Usually, a special toolholder is used to hold the cutting tool firmly during operation.
Dynamics of turning.
Forces.
The relative forces in a turning operation are important in the design of machine tools. The machine tool and its components must be able to withstand these forces without causing significant deflections, vibrations, or chatter during the operation. There are three principal forces during a turning process:
Speeds and feeds.
Speeds and feeds for turning are chosen based on cutter material, workpiece material, setup rigidity, machine tool rigidity and spindle power, coolant choice, and other factors.


Wire drawing

Wire drawing is a metalworking process used to reduce the cross-section of a wire by pulling the wire through a single, or series of, drawing die(s). There are many applications for wire drawing, including electrical wiring, cables, tension-loaded structural components, springs, paper clips, spokes for wheels, and stringed musical instruments. Although similar in process, drawing is different from extrusion, because in drawing the wire is pulled, rather than pushed, through the die. Drawing is usually performed at room temperature, thus classified as a cold working process, but it may be performed at elevated temperatures for large wires to reduce forces.
Of the elemental metals, copper, silver, gold, and platinum are the most ductile and immune from many of the problems associated with cold working.
Process.
The wire drawing process is quite simple in concept. The wire is prepared by shrinking the beginning of it, by hammering, filing, rolling or swaging, so that it will fit through the die; the wire is then pulled through the die. As the wire is pulled through the die, its volume remains the same, so as the diameter decreases, the length increases. Usually the wire will require more than one draw, through successively smaller dies, to reach the desired size. The American wire gauge scale is based on this. This can be done on a small scale with a draw plate, or on a large commercial scale using automated machinery. The process of wire drawing changes material properties due to cold working.
The area reduction in small wires is generally 15–25% and in larger wires is 20–45%. The exact die sequence for a particular job is a function of area reduction, input wire size and output wire size. As the area reduction changes, so does the die sequence.
Very fine wires are usually drawn in bundles. In a bundle, the wires are separated by a metal with similar properties, but with lower chemical resistance so that it can be removed after drawing. If the reduction in area is greater than 50%, the process may require an intermediate step of annealing before it can be redrawn.
Commercial wire drawing usually starts with a coil of hot rolled diameter wire. The surface is first treated to remove scales. It is then fed into a wire drawing machine which may have one or more blocks in series.
Single block wire drawing machines include means for holding the dies accurately in position and for drawing the wire steadily through the holes. The usual design consists of a cast-iron bench or table having a bracket standing up to hold the die, and a vertical drum which rotates and by coiling the wire around its surface pulls it through the die, the coil of wire being stored upon another drum or "swift" which lies behind the die and reels off the wire as fast as required. The wire drum or "block" is provided with means for rapidly coupling or uncoupling it to its vertical shaft, so that the motion of the wire may be stopped or started instantly. The block is also tapered, so that the coil of wire may be easily slipped off upwards when finished. Before the wire can be attached to the block, a sufficient length of it must be pulled through the die; this is effected by a pair of gripping pincers on the end of a chain which is wound around a revolving drum, so drawing the wire until enough can be coiled two or three times on the block, where the end is secured by a small screw clamp or vice. When the wire is on the block, it is set in motion and the wire is drawn steadily through the die; it is very important that the block rotates evenly and that it runs true and pulls the wire at a constant velocity, otherwise "snatching" occurs which will weaken or even break the wire. The speeds at which wire is drawn vary greatly, according to the material and the amount of reduction.
Machines with continuous blocks differ from single block machines by having a series of dies through which the wire is drawn in a continuous fashion. Due to the elongation and slips, the speed of the wire changes after each successive redraw. This increased speed is accommodated by having a different rotation speed for each block. One of these machines may contain 3 to 12 dies. The operation of threading the wire through all the dies and around the blocks is termed "stringing-up". The arrangements for lubrication include a pump which floods the dies, and in many cases also the bottom portions of the blocks run in lubricant.
Often intermediate anneals are required to counter the effects of cold working, and to allow further drawing. A final anneal may also be used on the finished product to maximize ductility and electrical conductivity.
An example of product produced in a continuous wire drawing machine is telephone wire. It is drawn 20 to 30 times from hot rolled rod stock.
While round cross-sections dominate most drawing processes, non-circular cross-sections are drawn. They are usually drawn when the cross-section is small and quantities are too low to justify rolling. In these processes, a block or Turk's-head machine are used.
Lubrication.
Lubrication in the drawing process is essential for maintaining good surface finish and long die life. The following are different methods of lubrication:
Various lubricants, such as oil, are employed. Another lubrication method is to immerse the wire in a copper(II) sulfate solution, such that a film of copper is deposited which forms a kind of lubricant. In some classes of wire the copper is left after the final drawing to serve as a preventive of rust or to allow easy soldering.The best example of copper coated wire is in MIG wire used in welding.
Mechanical properties.
The strength-enhancing effect of wire drawing can be substantial. The highest strengths available on any steel have been recorded on small-diameter cold-drawn austenitic stainless wire.
Drawing dies.
Drawing dies are typically made of tool steel, tungsten carbide, or diamond, with tungsten carbide and manufactured diamond being the most common. For drawing very fine wire a single crystal diamond die is used. For hot drawing, cast-steel dies are used. For steel wire drawing, a tungsten carbide die is used. The dies are placed in a steel casing, which backs the die and allow for easy die changes. Die angles usually range from 6–15°, and each die has at least 2 different angles: the entering angle and approach angle.


Transaction printing

Transaction Printing describes a mode of submitting a job to a printing device.
A digital printing system is attached to a computer database and many similar pages, called forms, are printed; each, for example, with a different person's data filling the form such as a monthly telephone or cable bill.
Simply stated, transaction printing is the printing of multiple transactions for each customer along with the fixed line details like name and address.
This is more used in BFSI sectors, for example, bank statements.
Transaction printing jobs are similar to, but often more complex than variable data printing jobs such as mail merge.
Transaction printing frequently requires customized formatting to present transaction data in a printable and customer-readable format.
Currently, printing applications are designed to print transactional details along with the external information (not available in the transaction database), often involving promotional material.
Transaction print jobs are different from 'publishing' print jobs in that the print controller does not know when the job will end when it starts. A transactional print job may involve a hundred, a thousand, or a few million impressions. Many digital printing system's controllers are designed to ingest the entire job, arrange its resources according to the size of the job and then begin printing the job last page first so that what is produced is a 'book' with the user seeing the first page first. This 'publishing' model obviously does not work for 'transaction' printing and a controller using a different internal model for jobs must be used.


Crankpin

A crankpin or crank pin, also known as a rod bearing journal, is a mechanical device in an engine which connects the crankshaft to the connecting rod for each cylinder. It has a cylindrical surface, to allow the crankpin to rotate relative to the "big end" of the connecting rod.
The most common configuration is for a crankpin to serve one cylinder. However, many V engines have each crankpin shared by each pair of cylinders.
Design.
The crankpin connects to the larger end of the connecting rod for each cylinder. This end of the connecting rod is called the "big end", as opposed to the "small end" or "little end" (which connects to the wrist/gudgeon pin in the piston).
The bearing which allows the crankpin to rotate around its shaft is called the "rod bearing". In automotive engines, the most common type of rod bearing is the plain bearing, however bushings or roller bearings are also used in some engines.
Configurations.
In a single-cylinder engine, straight engine or flat engine, each crankpin normally serves just one cylinder. This results for a relatively simple design which is the cheapest to produce. Some V-twin engines use a single cylinder per crankpin.
Most V engines have each pair of cylinders sharing a crankpin. This usually requires an offset between the cylinders in each bank, resulting in a simple connecting rod design. If a cylinder offset is not used, then the connecting rods must be articulated or forked at the big end. Forked connecting rods are mainly used in V-twin motorcycle engines, but in the past were found on a number of automobile and aero engines, such as the Rolls-Royce Merlin aero engine of the WWII era. Articulated connecting rods consist of a "master" rod attached to the crank pin, with a "slave" rod connected to the big end of the master rod. This design was used in older or exotic V engines.
Radial engines use a more complicated version of articulated connecting rods, where a single "master" connecting rod attached to the single crankpin (one for each row in multi-row designs), and smaller bearings for each of the corresponding cylinders machined into the big end of the master rod.
Cylindrical crank pins were fitted onto the driving wheels of steam locomotives. They were connected to the driving rods that transmitted power from the cylinder to the wheel. The crank pin was usually made of high-quality steel because it had to withstand high forces.
The crank pin of a locomotive corresponds to the offset of a crankshaft in other crank drives. The distance from the centre of the crank pin to the centre of the wheel is also called offset and is exactly half the stroke of the pistons.


Electroforming

Electroforming is a metal forming process in which parts are fabricated through electrodeposition on a model, known in the industry as a mandrel. Conductive (metallic) mandrels are treated to create a mechanical parting layer, or are chemically passivated to limit electroform adhesion to the mandrel and thereby allow its subsequent separation. Non-conductive (glass, silicon, plastic) mandrels require the deposition of a conductive layer prior to electrodeposition. Such layers can be deposited chemically, or using vacuum deposition techniques (e.g., gold sputtering). The outer surface of the mandrel forms the inner surface of the form.
The process involves passing direct current through an electrolyte containing salts of the metal being electroformed. The anode is the solid metal being electroformed, and the cathode is the mandrel, onto which the electroform gets plated (deposited). The process continues until the required electroform thickness is achieved. The mandrel is then either separated intact, melted away, or chemically dissolved.
The surface of the finished part that was in intimate contact with the mandrel is replicated in fine detail with respect to the original, and is not subject to the shrinkage that would normally be experienced in a foundry cast metal object, or the tool marks of a milled part. The solution side of the part is less well defined, and that loss of definition increases with thickness of the deposit. In extreme cases, where a thickness of several millimetres is required, there is preferential build-up of material on sharp outside edges and corners. This tendency can be reduced by shielding, or a process known as periodic reverse, where the electroforming current is reversed for short periods and the excess is preferentially dissolved electrochemically. The finished form can either be the finished part, or can be used in a subsequent process to produce a positive of the original mandrel shape, such as with vinyl records or CD and DVD stamper manufacture.
In recent years, due to its ability to replicate a mandrel surface with practically no loss of fidelity, electroforming has taken on new importance in the fabrication of micro and nano-scale metallic devices and in producing precision injection molds with micro- and nano-scale features for production of non-metallic micro-molded objects.
Process.
In the basic electroforming process, an electrolytic bath is used to deposit nickel or other electroformable metal onto a conductive surface of a model (mandrel). Once the deposited material has been built up to the desired thickness, the electroform is parted from the substrate. This process allows precise replication of the mandrel surface texture and geometry at low unit cost with high repeatability and excellent process control.
If the mandrel is made of a non-conductive material it can be coated with a thin conductive layer.
Advantages and disadvantages.
The main advantage of electroforming is that it accurately replicates the external shape of the mandrel. Generally, machining a cavity accurately is more challenging than machining a convex shape, however the opposite holds true for electroforming because the mandrel's exterior can be accurately machined and then used to electroform a precision cavity.
Compared to other basic metal forming processes (casting, forging, stamping, deep drawing, machining and fabricating) electroforming is very effective when requirements call for extreme tolerances, complexity or light weight. The precision and resolution inherent in the photo-lithographically produced conductive patterned substrate, allows finer geometries to be produced to tighter tolerances while maintaining superior edge definition with a near optical finish. Electroformed metal can be extremely pure, with superior properties over wrought metal due to its refined crystal structure. Multiple layers of electroformed metals can be bonded together, or to different substrate materials to produce complex structures with "grown-on" flanges and bosses.
Tolerances of 1.5 to 3 nanometres have been reported.
A wide variety of shapes and sizes can be made by electroforming, the principal limitation being the need to part the product from the mandrel. Since the fabrication of a product requires only a single model or mandrel, low production quantities can be made economically.


Demand signal

A demand signal is a message issued within business operations or within a supply chain to notify a supplier that goods are required, and is, therefore, a key item of information for demand planners within a business.
Contexts.
In a Just-in-time manufacturing or operations context, a demand signal identifies a need for new materials and triggers a delivery from an internal store or an external supplier. The Kanban system uses cards ('Kanban cards') to mark the stock level at which a replenishment signal needs to be issued. Kanban cards are a key component of a kanban system as they signal the need to move materials within a production facility or to move materials from an outside supplier into the production facility. The kanban card is, in effect, a message which signals depletion of product, parts, or inventory. When received, the kanban triggers replenishment of that product, part, or inventory. Consumption, therefore, drives demand for more production, and the kanban card signals demand more product — so kanban cards help create a demand-driven system.
In the context of an Enterprise Resource Planning (ERP) system, demand signals function as granular data indicating discrete requests for the supply or use of a resource. Demand Signal Management (DSiM) provides a means of harmonizing demand data so that it can be used in demand planning. Demand signals must bring together data on actual sales and date on unfulfilled demand in order to be effective.


Metal bellows

Metal bellows are elastic vessels that can be compressed when pressure is applied to the outside of the vessel, or extended under vacuum. When the pressure or vacuum is released, the bellows will return to its original shape, provided the material has not been stressed past its yield strength. They are used both for their ability to deform under pressure and to provide a hermetic seal that allows movement.
Precision bellows technology of the 20th and 21st century is centered on metal bellows with less demanding applications using ones made of rubber and plastic. These products bear little resemblance to the original leather bellows used traditionally in fireplaces and forges.
Types.
There are three main types of metal bellows: formed, welded and electroformed.
Formed bellows are produced by reworking tubes, normally produced by deep drawing, with a variety of processes, including cold forming (rolling), and hydroforming. They are also called convoluted bellows or sylphons.
Welded bellows (also called edge-welded, or diaphragm bellows) are manufactured by welding a number of individually formed diaphragms to each other. The comparison between the two bellows types generally centers on cost and performance. Hydroformed bellows generally have a high tooling cost, but, when mass-produced, may have a lower piece price. However, hydroformed bellows have lower performance characteristics due to relatively thick walls and high stiffness. Welded metal bellows are produced with a lower initial tooling cost and maintain higher performance characteristics. The drawback of welded bellows is the reduced metal strength at weld joints, caused by the high temperature of welding.
Electroformed bellows are produced by plating (electroforming) a metal layer onto a model (mandrel), and subsequently removing the mandrel. They can be produced with modest tooling costs and with thin walls (25 micrometres or less), providing such bellows with high sensitivity and precision in many exacting applications, and may also be produced in shapes that would be exceptionally difficult to produce by other means with little additional difficulty.
Another area of comparison is in metals of construction. Hydroformed and rolled bellows are limited to metals with high plastic elongation characteristics, whereas welded bellows may be fabricated from a wider variety of standard and exotic alloys, such as stainless steel and titanium, as well as other high-strength, corrosion-resistant materials. Electroformed bellows can be produced of nickel, its high-strength alloys, and copper.
Applications.
Metal bellows are used in a large number of industrial applications. Below you will find a few;
Manufacture.
Welded bellows can be fabricated from a variety of exotic metals and alloys, whereas formed bellows are limited to alloys with good elongation – brass being a prime example. Welded bellows are not fabricated from brass because of its fundamentally poor weldability. Other advantages to welded bellows include compactness (higher performance in a smaller package), ability to be compressed to solid height with no damage, resistance to nicks and dents, and dramatically greater flexibility.
The welding of metal bellows is a microscopic welding process, typically performed under laboratory conditions at high magnification.
Hydroformed bellows are produced by forcing a metal tube to expand under hydraulic pressure inside a bellows-shaped mold, and assume the convoluted shape of the mold.
Electroformed bellows are produced by plating metal onto a bellows-shaped model (mandrel), and the subsequent mandrel removal by chemical or physical means. Due to the low tooling cost and short manufacturing cycle, electroforming of bellows is not only an inexpensive manufacturing method, but also a perfect prototyping tool.
Deflections.
There are a variety of expansion joints and not each one can accept the same types of deflection. The various types of deflections are axial, lateral, angular, torsional, cyclic, or any combination that can occur at the same time.


Process validation

Process validation is the analysis of data gathered throughout the design and manufacturing of a product in order to confirm that the process can reliably output products of a determined standard. Regulatory authorities like EMA and FDA have published guidelines relating to process validation. The purpose of process validation is to ensure varied inputs lead to consistent and high quality outputs. Process validation is an ongoing process that must be frequently adapted as manufacturing feedback is gathered. End-to-end validation of production processes is essential in determining product quality because quality cannot always be determined by finished-product inspection. Process validation can be broken down into 3 steps: process design (Stage 1a, Stage 1b), process qualification (Stage 2a, Stage 2b), and continued process verification (Stage 3a, Stage 3b).
Stage 1: Process Design.
In this stage, data from the development phase are gathered and analyzed to define the commercial manufacturing process. By understanding the commercial process, a framework for quality specifications can be established and used as the foundation of a control strategy. Process design is the first of three stages of process validation. Data from the development phase is gathered and analyzed to understand end-to-end system processes. These data are used to establish benchmarks for quality and production control.
Design of experiment (DOE).
Design of experiments is used to discover possible relationships and sources of variation as quickly as possible. A cost-benefit analysis should be conducted to determine if such an operation is necessary.
Quality by design (QBD).
Quality by design is an approach to pharmaceutical manufacturing that stresses quality should be built into products rather than tested in products; that product quality should be considered at the earliest possible stage rather than at the end of the manufacturing process. Input variables are isolated in order to identify the root cause of potential quality issues and the manufacturing process is adapted accordingly.
Process analytical technology (PAT).
Process analytical technology is used to measure critical process parameters (CPP) and critical quality attributes (CQA). PAT facilitates measurement of quantitative production variables in real time and allows access to relevant manufacturing feedback. PAT can also be used in the design process to generate a process qualification.
Critical process parameters (CPP).
Critical process parameters are operating parameters that are considered essential to maintaining product output within specified quality target guidelines.
Critical quality attributes (CQA).
Critical quality attributes (CQA) are chemical, physical, biological, and microbiological attributes that can be defined, measured, and continually monitored to ensure final product outputs remain within acceptable quality limits. CQA are an essential aspect of a manufacturing control strategy and should be identified in stage 1 of process validation: process design. During this stage, acceptable limits, baselines, and data collection and measurement protocols should be established. Data from the design process and data collected during production should be kept by the manufacturer and used to evaluate product quality and process control. Historical data can also help manufacturers better understand operational process and input variables as well as better identify true deviations from quality standards compared to false positives. Should a serious product quality issue arise, historical data would be essential in identifying the sources of errors and implementing corrective measures.
Stage 2: Process Performance Qualification.
In this stage, the process design is assessed to conclude if the process is able to meet determined manufacturing criteria. In this stage all production processes and manufacturing equipment is proofed to confirm quality and output capabilities. Critical quality attributes are evaluated, and critical process parameters taken into account, to confirm product quality. Once the process qualification stage has been successfully accomplished, production can begin. Process Performance Qualification is the second phase of process validation.
Stage 3: Continued Process Verification.
Continued process verification is the ongoing monitoring of all aspects of the production cycle. It aims to ensure that all levels of production are controlled and regulated. Deviations from prescribed output methods and final product irregularities are flagged by a process analytics database system. The FDA requires production data be recorded (FDA requirements (§ 211.180(e)). Continued process verification is stage 3 of process validation.
The European Medicines Agency defines a similar process known as "ongoing process verification". This alternative method of process validation is recommended by the EMA for validating processes on a continuous basis. Continuous process verification analyses critical process parameters and critical quality attributes in real time to confirm production remains within acceptable levels and meets standards set by ICH Q8, Pharmaceutical Quality Systems, and Good manufacturing practice.


Surface finish

Surface finish, also known as surface texture or surface topography, is the nature of a surface as defined by the three characteristics of lay, surface roughness, and waviness. It comprises the small, local deviations of a surface from the perfectly flat ideal (a true plane).
Surface texture is one of the important factors that control friction and transfer layer formation during sliding. Considerable efforts have been made to study the influence of surface texture on friction and wear during sliding conditions. Surface textures can be isotropic or anisotropic. Sometimes, stick-slip friction phenomena can be observed during sliding, depending on surface texture.
Each manufacturing process (such as the many kinds of machining) produces a surface texture. The process is usually optimized to ensure that the resulting texture is usable. If necessary, an additional process will be added to modify the initial texture. The latter process may be grinding (abrasive cutting), polishing, lapping, abrasive blasting, honing, electrical discharge machining (EDM), milling, lithography, industrial etching/chemical milling, laser texturing, or other processes.
Lay.
Lay is the direction of the predominant surface pattern, ordinarily determined by the production method used. The term is also used to denote the winding direction of fibers and strands of a rope.
Surface roughness.
Surface roughness, commonly shortened to "roughness," is a measure of the total spaced surface irregularities. In engineering, this is what is usually meant by "surface finish." A Lower number constitutes finer irregularities, i.e., a smoother surface.
Waviness.
Waviness is the measure of surface irregularities with a spacing greater than that of surface roughness. These irregularities usually occur due to warping, vibrations, or deflection during machining.
Measurement.
Surface finish may be measured in two ways: "contact" and "non-contact" methods. Contact methods involve dragging a measurement stylus across the surface; these instruments are called profilometers. Non-contact methods include: interferometry, confocal microscopy, focus variation, structured light, electrical capacitance, electron microscopy, atomic force microscopy and photogrammetry.
Specification.
In the United States, surface finish is usually specified using the ASME Y14.36M standard. The other common standard is International Organization for Standardization (ISO) 1302:2002, although the same has been withdrawn in favour of ISO 21920-1:2021.
Many factors contribute to the surface finish in manufacturing. In forming processes, such as molding or metal forming, surface finish of the die determines the surface finish of the workpiece. In machining, the interaction of the cutting edges and the microstructure of the material being cut both contribute to the final surface finish.
In general, the cost of manufacturing a surface increases as the surface finish improves. Any given manufacturing process is usually optimized enough to ensure that the resulting texture is usable for the part's intended application. If necessary, an additional process will be added to modify the initial texture. The expense of this additional process must be justified by adding value in some way—principally better function or longer lifespan. Parts that have sliding contact with others may work better or last longer if the roughness is lower. Aesthetic improvement may add value if it improves the saleability of the product.
A practical example is as follows. An aircraft maker contracts with a vendor to make parts. A certain grade of steel is specified for the part because it is strong enough and hard enough for the part's function. The steel is machinable although not free-machining. The vendor decides to mill the parts. The milling can achieve the specified roughness (for example, ≤ 3.2 μm) as long as the machinist uses premium-quality inserts in the end mill and replaces the inserts after every 20 parts (as opposed to cutting hundreds before changing the inserts). There is no need to add a second operation (such as grinding or polishing) after the milling as long as the milling is done well enough (correct inserts, frequent-enough insert changes, and clean coolant). The inserts and coolant cost money, but the costs that grinding or polishing would incur (more time and additional materials) would cost even more than that. Obviating the second operation results in a lower unit cost and thus a lower price. The competition between vendors elevates such details from minor to crucial importance. It was certainly possible to make the parts in a slightly less efficient way (two operations) for a slightly higher price; but only one vendor can get the contract, so the slight difference in efficiency is magnified by competition into the great difference between the prospering and shuttering of firms.
Just as different manufacturing processes produce parts at various tolerances, they are also capable of different roughnesses. Generally, these two characteristics are linked: manufacturing processes that are dimensionally precise create surfaces with low roughness. In other words, if a process can manufacture parts to a narrow dimensional tolerance, the parts will not be very rough.
Due to the abstractness of surface finish parameters, engineers usually use a tool that has a variety of surface roughnesses created using different manufacturing methods.


Diffusion bonding

Diffusion bonding or diffusion welding is a solid-state welding technique used in metalworking, capable of joining similar and dissimilar metals. It operates on the principle of solid-state diffusion, wherein the atoms of two solid, metallic surfaces intersperse themselves over time. This is typically accomplished at an elevated temperature, approximately 50-75% of the absolute melting temperature of the materials. Diffusion bonding is usually implemented by applying high pressure, in conjunction with necessarily high temperature, to the materials to be welded; the technique is most commonly used to weld "sandwiches" of alternating layers of thin metal foil, and metal wires or filaments. Currently, the diffusion bonding method is widely used in the joining of high-strength and refractory metals within the aerospace and nuclear industries.
History.
The act of diffusion welding is centuries old. This can be found in the form of "gold-filled," a technique used to bond gold and copper for use in jewelry and other applications. In order to create filled gold, smiths would begin by hammering out an amount of solid gold into a thin sheet of gold foil. This film was then placed on top of a copper substrate and weighted down. Finally, using a process known as "hot-pressure welding" or HPW, the weight/copper/gold-film assembly was placed inside an oven and heated until the gold film was sufficiently bonded to the copper substrate.
Modern methods were described by the Soviet scientist N.F. Kazakov in 1953.
Characteristics.
Diffusion bonding involves no liquid fusion, and often no filler metal. No weight is added to the total, and the join tends to exhibit both the strength and temperature resistance of the base metal(s). The materials endure no, or very little, plastic deformation. Very little residual stress is introduced, and there is no contamination from the bonding process. It may theoretically be performed on a join surface of any size with no increase in processing time, however, practically speaking, the surface tends to be limited by the pressure required and physical limitations. Diffusion bonding may be performed with similar and dissimilar metals, reactive and refractory metals, or pieces of varying thicknesses.
Due to its relatively high cost, diffusion bonding is most often used for jobs either difficult or impossible to weld by other means. Examples include welding materials normally impossible to join via liquid fusion, such as zirconium and beryllium; materials with very high melting points such as tungsten; alternating layers of different metals which must retain strength at high temperatures; and very thin, honeycombed metal foil structures. Titanium alloys will often be diffusion bonded despite as the thin oxide layer can be dissolved and diffused away from the bonding surfaces at temperatures over 850 °C.
Temperature Dependence.
Steady state diffusion is determined by the amount of diffusion flux that passes through the cross-sectional area of the mating surfaces. Fick's first law of diffusion states:
where "J" is the diffusion flux, "D" is a diffusion coefficient, and "dC"/"dx" is the concentration gradient through the materials in question. The negative sign is a product of the gradient. Another form of Fick's law states:
where "M" is defined as either the mass or amount of atoms being diffused, "A" is the cross-sectional area, and "t" is the time required. Equating the two equations and rearranging, we achieve the following result:
As mass and area are constant for a given joint, time required is largely dependent on the concentration gradient, which changes by only incremental amounts through the joint, and the diffusion coefficient. The diffusion coefficient is determined by the equation:
where "Q"d is the activation energy for diffusion, "R" is the universal gas constant, "T" is the thermodynamic temperature experienced during the process, and "D"0 is a temperature-independent preexponential factor that depends on the materials being joined. For a given joint, the only term in this equation within control is temperature.
Processes.
When joining two materials of similar crystalline structure, diffusion bonding is performed by clamping the two pieces to be welded with their surfaces abutting each other. Prior to welding, these surfaces must be machined to as smooth a finish as economically viable, and kept as free from chemical contaminants or other detritus as possible. Any intervening material between the two metallic surfaces may prevent adequate diffusion of material. Specific tooling is made for each welding application to mate the welder to the workpieces. Once clamped, pressure and heat are applied to the components, usually for many hours. The surfaces are heated either in a furnace, or via electrical resistance. Pressure can be applied using a hydraulic press at temperature; this method allows for exact measurements of load on the parts. In cases where the parts must have no temperature gradient, differential thermal expansion can be used to apply load. By fixturing parts using a low-expansion metal (i.e. molybdenum) the parts will supply their own load by expanding more than the fixture metal at temperature. Alternative methods for applying pressure include the use of dead weights, differential gas pressure between the two surfaces, and high-pressure autoclaves. Diffusion bonding must be done in a vacuum or inert gas environment when using metals that have strong oxide layers (i.e. copper). Surface treatment including polishing, etching, and cleaning as well as diffusion pressure and temperature are important factors regarding the process of diffusion bounding.
At the microscopic level, diffusion bonding occurs in three simplified stages:
Applicability.
Diffusion bonding is primarily used to create intricate forms for the electronics, aerospace, nuclear, and microfluidics industries. Since this form of bonding takes a considerable amount of time compared to other joining techniques such as explosion welding, parts are made in small quantities, and often fabrication is mostly automated. However, due to different requirements, the required time could be reduced. In an attempt to reduce fastener count, labor costs, and part count, diffusion bonding, in conjunction with superplastic forming, is also used when creating complex sheet metal forms. Multiple sheets are stacked atop one another and bonded in specific sections. The stack is then placed into a mold and gas pressure expands the sheets to fill the mold. This is often done using titanium or aluminum alloys for parts needed in the aerospace industry.
Typical materials that are welded include titanium, beryllium, and zirconium. In many military aircraft diffusion bonding will help to allow for the conservation of expensive strategic materials and the reduction of manufacturing costs. Some aircraft have over 100 diffusion-bonded parts, including fuselages, outboard and inboard actuator fittings, landing gear trunnions, and nacelle frames.


Self-assembly based manufacturing

Self-assembly based manufacturing refers to a controlled process of using self-assembly and programmable matter to manufacture a product on an industrial scale. In traditional manufacturing and fabrication, there are physical and precision limitations on a workpiece; namely, lower minimal dimension of a workpiece has been a major challenge in modern manufacturing. Engineering self-assembly methods have a significant potentials in overcoming the dimensional limitation of a workpiece. In general, there are three key ingredients in most of self assembly applications: geometry (order), interaction, energy. To improve the efficiency or take shape in self-assembly based manufacturing, it must utilize one or more than one of these three ingredients. This is an emerging market with few examples to date. However, this field shows a strong potential to revolutionize many industrial markets from nanoelectronics to bio-engineering.
Successful processes.
Many processes have been successfully developed at laboratory scale and show promise for future expansion into large-scale industrial manufacturing.
One example is the automated reel to reel fluidic self-assembly machine demonstrated by University of Minnesota researchers. The machine was designed to produce lighting panels using Light-emitting diodes. Assembly was performed at twice the hourly rate of commercially available pick and place machines for SMT placement equipment, 15,000 chips per hour compared to 8,000 chips per hour. At the same time, the self-assembly exceeded the accuracy rate of the pick and place machine as well.
Potential future applications.
Fabrication of materials used in most extreme environments, such as space, high altitude, free-fall scenarios, or deep sea. environments have advantageous conditions for allowing increase in self assembly interaction with less or minimum energy consumption. Applications in these environments often require high precision and have more difficulties; however, it has less constraints in existing construction.


Solder ball

In integrated circuit packaging, a solder ball, also a solder bump (often referred to simply as "ball" or "bumps") is a ball of solder that provides the contact between the chip package and the printed circuit board, as well as between stacked packages in multichip modules; in the latter case, they may be referred to as microbumps (μbumps, ubumps), since they are usually significantly smaller than the former. The solder balls can be placed manually or by automated equipment, and are held in place with a tacky flux.
A coined solder ball is a solder ball subject to coining, i.e., flattening to a shape resembling that of a coin, to increase contact reliability.
The ball grid array, chip-scale package, and flip chip packages generally use solder balls.
Underfill.
After the solder balls are used to attach an integrated circuit chip to a PCB, often the remaining air gap between them is underfilled with epoxy.
In some cases, there may be multiple layers of solder balls—for example, one layer of solder balls attaching a flip chip to an interposer to form a BGA package, and a second layer of solder balls attaching that interposer to the PCB. Often both layers are underfilled.


Laser beam machining

Laser beam machining (LBM) is a form of machining that uses heat directed from a laser beam. This process uses thermal energy to remove material from metallic or nonmetallic surfaces. The high frequency of monochromatic light will fall on the surface, thus heating, melting and vaporizing the material due to the impinge of photons (see Coulomb explosion).
Laser beam machining is best suited for brittle materials with low conductivity, but can be used on most materials.
Laser beam machining can be done on glass without melting the surface. With photosensitive glass, the laser alters the chemical structure of the glass allowing it to be selectively etched. The glass is also referred to as photomachinable glass. The advantage of photomachinable glass is that it can produce precisely vertical walls and the native glass is suitable for many biological applications such as substrates for genetic analysis.
Types of lasers.
There are many different types of lasers including gas, solid states lasers, and excimer.
Some of the most commonly used gases consist of; He-Ne, Ar, and Carbon dioxide laser.
Solid-state lasers are designed by doping a rare element into various host materials. Unlike in gas lasers, solid state lasers are pumped optically by flash lamps or arc lamps. Ruby is one of the frequently used host materials in this type of laser. A ruby laser is a type of the solid state laser whose laser medium is a synthetic ruby crystal. The synthetic ruby rod is optically pumped using a xenon flashtube before it is used as an active laser medium.
YAG is an abbreviation for yttrium aluminum garnet which are crystals that are used for solid-state lasers while refers to neodymium-doped yttrium aluminum garnet crystals that are used in the solid-state lasers as the laser mediate.
YAG lasers emit a wavelength of light waves with high energy. is neodymium–doped gain media made of either silicate or phosphate materials that are used in fiber laser.
Cutting depth.
The cutting depth of a laser is directly proportional to the quotient obtained by dividing the power of the laser beam by the product of the cutting velocity and the diameter of the laser beam spot.
where "t" is the depth of cut, "P" is the laser beam power, "v" is the cutting velocity, and "d" is the laser beam spot diameter.
The depth of the cut is also influenced by the workpiece material. The material's reflectivity, density, specific heat, and melting point temperature all contribute to the lasers ability to cut the workpiece.
The following table shows the ability of different lasers to cut different materials:
Applications.
Lasers can be used for welding, cladding, marking, surface treatment, drilling, and cutting among other manufacturing processes. It is used in the automobile, shipbuilding, aerospace, steel, electronics, and medical industries for precision machining of complex parts.
Laser welding is advantageous in that it can weld at speeds of up to 100 mm/s as well as the ability to weld dissimilar metals. Laser cladding is used to coat cheap or weak parts with a harder material in order to improve the surface quality. Drilling and cutting with lasers is advantageous in that there is little to no wear on the cutting tool as there is no contact to cause damage.
Milling with a laser is a three dimensional process that requires two lasers, but drastically cuts costs of machining parts. Lasers can be used to change the surface properties of a workpiece.
The appliance of laser beam machining varies depending on the industry. In light manufacturing the machine is used to engrave and to drill other metals. In the electronic industry laser beam machining is used for wire stripping and skiving of circuits. In the medical industry it is used for cosmetic surgery and hair removal.


Mirror mount

A mirror mount is a device that holds a mirror. In optics research, these can be quite sophisticated devices, due to the need to be able to tip and tilt the mirror by controlled amounts, while still holding it in a precise position when it is not being adjusted.
An optical mirror mount generally consists of a movable front plate which holds the mirror, and a fixed back plate with adjustment screws. Adjustment screws drive the front plate about the axes of rotation in the pitch (vertical) and yaw (horizontal) directions. An optional third actuator often enables z-axis translation.
Precision mirror mounts can be quite expensive, and a notable amount of engineering goes into their design. Such sophisticated mounts are often required for lasers, interferometers, and optical delay lines.
Types of mirror mount.
The most common type of mirror mount is the kinematic mount. This type of mount is designed according to the principles of kinematic determinacy. Typically, the movable frame that holds the mirror pivots on a ball bearing which is set into a hole in the fixed frame. Ideally, this hole should be trihedral (pyramid-shaped). Often a conical hole is used due to easier manufacture. The frame is pivoted by means of two micrometers or fine-thread screws, tipped with steel ball bearings. One of these ball bearings rests in a V-groove, the other rests on a flat surface. On cheaper mounts, the flat surface may be simply the material of the mount. In more expensive mounts, the flat surface (and perhaps the hole and v-groove too) may be made out of a much harder material (often sapphire), set into the frame.
The reason for this strange mechanism is that the first ball (ideally) makes contact with the fixed frame at exactly three points, the second ball at two, and the third ball at just one. These six points of contact exactly constrain the six degrees of freedom for motion of the movable frame. This leads to precise movement of the frame when the micrometers or screws are turned, without unnecessary wobble or friction.
A disadvantage of kinematic mounts is that the center of the mirror moves along its normal axis, when the mirror is rotated. This is because the center of rotation is the middle of the first ball bearing, not the center of the mirror. For optical cavities and interferometers, it is often desirable to be able to align the mirrors separately from adjustments to the length of the cavity. For these applications and others, a more sophisticated mount is required.
One way of eliminating this translation along the axis is to set the first ball on a fine-thread screw as well. By appropriate adjustment of all three screws, the mirror can be tilted in either direction without translation. The screws can by driven by a motor under computer control to make this seem to the operator like simple rotation about a virtual pivot point in the center of the mirror surface. The translation can instead be eliminated mechanically by using a gimbal mount, which uses two rings that each pivot about a line running through the center of the mirror. This gives kinematically correct two-axis rotation about the center of the mirror.
With both types of mount, springs are needed to keep the frame pressed against the ball bearings, unless the mount is designed to be used only in an orientation where gravity will keep the frame in place. Following the cantilever principle, a large mount allows finer control than a smaller one. The frames are ideally made of a light material, to make the resonant frequency of the structure high. This reduces vibration, since many common sources of vibration are relatively low frequency. For stability, the fixed frame is supported by a rigid mount that is securely bolted to a supporting surface. In a laboratory environment, this is typically an optical table. A shock can cause the mount to move away from the ball bearings, but because there are only 6, hard contacts, the mirror will return to the original position, preserving the alignment.
The mount itself has to avoid deformation of the mounted optics. Stress from mounting can introduce aberration in the light reflected from a mirror, or photoelasticity inside a lens. In some lasers the mirrors have to be easily replaced, in which case the mount needs to be designed to allow the mirror to be removed and replaced without losing the correct alignment.
Operation.
The fine-thread screws show a slip and stick behaviour; when used manually, a torque is applied with two fingers until the thread slips a bit, then the new position is read on a scale. Inexpensive screws do long slips and lack a scale. Precision micrometers perform better and provide a scale for reference. When used remotely, an electric motor is used to apply short pulses of torque. The motor is firmly connected with the screw and the thread and nothing else so that the pulse is absorbed by friction. To read out the position electronically, a rotary encoder is attached. When the ball is not completely centered on the screw and the axis is not normal to the mirror surface (which is an explicit feature of some convenience mirror mounts), a small sinus movement of the mirror is overlaid onto the linear movement, which a controller could compensate for. For analog fine control (5 nm), piezos are built into the mobile frame.
Applications.
Laser cavity end mirrors need very precise alignment. Due to their low divergence laser beams need precise steering mirrors. For rapid prototyping on an optical table mirror mounts can be used to hold other elements besides mirrors, for example lenses often need to be aligned for minimal coma. Sometimes prisms only need two axes alignment and can be mounted on a mirror mount rather than a three-axis prism table.
Critical phase matched crystals can be aligned and tuned precisely with a standard mirror mount. The same is true for small etalons, retarders and polarizers. Furthermore, mirror mounts using magnets instead of springs allow the mobile frame to be removed and later replaced in exactly the same position.


Optomechatronics

In engineering, optomechatronics is a field that investigates the integration of optical components and technology into mechatronic systems. The optical components in these systems are used as sensors to measure mechanical quantities such as surface structure and orientation. Optical sensors are used in a feedback loop as part of control systems for mechatronic devices. Optomechatronics has applications in areas such as adaptive optics, vehicular automation, optofluidics, optical tweezers and thin-film technology.


Total productive maintenance

Total productive maintenance (TPM) started as a method of physical asset management, focused on maintaining and improving manufacturing machinery in order to reduce the operating cost to an organization. After the PM award was created and awarded to Nippon Denso in 1971, the JIPM (Japanese Institute of Plant Maintenance), expanded it to include 8 Activities of TPM that required participation from all areas of manufacturing and non-manufacturing in the concepts of lean manufacturing.
TPM is designed to disseminate the responsibility for maintenance and machine performance, improving employee engagement and teamwork within management, engineering, maintenance, and operations.
There are eight types of Activities in TPM implementation process:
History.
Total productive maintenance (TPM) was developed by Seiichi Nakajima in Japan between 1950 and 1970. This experience led to the recognition that a leadership mindset engaging front line teams in small group improvement activity is an essential element of effective operation. The outcome of his work was the application of the TPM process in 1971. One of the first companies to gain from this was Nippondenso, a company that created parts for Toyota. They became the first winner of the PM prize. An internationally accepted TPM benchmark developed by the JIPM Seiichi Nakajima is therefore regarded as the father of TPM. The classic TPM process he developed consisting of 5 principles was later enhanced by the JIPM to incorporate many of the lessons of lean manufacturing and is referred to as Company-Wide TPM which consists of 8 principles/activities. The name "Pillar" is symbolically used as a structural support to the structure of TPM. The term "activities" is more appropriate since execution of these 8 activities is the process of TPM implementation.
Objectives.
The goal of TPM is the improvement of equipment effectiveness through engaging those that impact on it in small group improvement activities. Total quality management (TQM) and total productive maintenance (TPM) are considered as the key operational activities of the quality management system. In order for TPM to be effective, the full participation of entire organisation from top to frontline operators is vital. This should result in accomplishing the goal of TPM: "Enhance the volume of the production, employee morals, and job satisfaction."
The main objective of TPM is to increase the Overall Equipment Effectiveness (OEE) of plant equipment. TPM addresses the causes for accelerated deterioration and production losses while creating the correct environment between operators and equipment to create ownership.
OEE has three factors which are multiplied to give one measure called OEE
Performance x Availability x Quality = OEE
Each factor has two associated losses making 6 in total, these 6 losses are as follows:
Performance = (1) running at reduced speed – (2) Minor Stops
Availability = (3) Breakdowns – (4) Product changeover
Quality = (5) Startup rejects – (6) Running rejects
The objective finally is to identify then prioritize and eliminate the causes of the losses. This is done by self-managing teams that solve problems. Employing consultants to create this culture is a common practice.
Principles.
The eight pillars of TPM are mostly focused on proactive and preventive techniques for improving equipment reliability:
With the help of these pillars, we can increase productivity.
Manufacturing support.
Implementation.
Following are the steps involved by the implementation of TPM in an organization:
According to Nicholas, the steering committee should consist of production managers, maintenance managers, and engineering managers. The committee should formulate TPM policies and strategies and give advice. This committee should be led by a top-level executive. Also a TPM program team must rise, this program team has oversight and coordination of implementation activities. As well, it's lacking some crucial activities, like starting with partial implementation. Choose the first target area as a pilot area, this area will demonstrate the TPM concepts. Lessons learned from early target areas/the pilot area can be applied further in the implementation process.
Difference from TQM.
Total quality management and total productive maintenance are often used interchangeably. However, TQM and TPM share a lot of similarities but are considered as two different approaches in the official literature. TQM attempts to increase the quality of goods, services, and concomitant customer satisfaction by raising awareness of quality concerns across the organization.
TQM is based on five cornerstones: The product, the process that allows the product to be produced, the organization that provides the proper environment needed for the process to work, the leadership that guides the organization, and commitment to excellence throughout the organization.
In other words, TQM focuses on the quality of the product, while TPM focuses on the losses that impede the equipment used to produce the products. By preventing equipment break-down, improving the quality of the equipment and by standardizing the equipment (results in less variance, so better quality), the quality of the products increases. TQM and TPM can both result in an increase in quality. However, the way of going there is different. TPM can be seen as a way to help to achieve the goal of TQM.


Tombstone (manufacturing)

A tombstone, also known as a pedestal-type fixture, tooling tower, tooling column or fixture block, is a fixture of two or more sides, onto which are mounted parts to be manufactured. Tombstones are typically used in automated systems; parts are loaded onto the tombstone so that robots may operate on one part, flip the tombstone, and operate on the next part until all processes are completed, then transport the entire tombstone to the next station.
The first tombstone type fixture was patented in 1971 by the Vereinigte Flugtechnische Werke.
Tombstones are used in agile manufacturing to facilitate quick and easy installation, scalability and reconfiguration.


Hardfacing

Hardfacing is a metalworking process where harder or tougher material is applied to a base metal. It is welded to the base material, and generally takes the form of specialized electrodes for arc welding or filler rod for oxyacetylene and gas tungsten arc welding welding. Powder metal alloys are used in (PTA) also called powder plasma welding and thermal spray processes like high-velocity oxygen fuel coating, plasma spray, spray and fuse, etc. Submerged arc welding, FCAW (Flux Core Arc Welding) and MIG (Metal Inert Gas) / MAG (Metal Active Gas) uses continuously fed wire varying in diameter depending on process and current. Strip cladding process uses strips from 50 mm wide to 125 mm with a thickness of 0.5mm. Open arc welding uses continuously fed tubular electrode which may or may not contain flux.
Hardfacing may be applied to a new part during production to increase its wear resistance, or it may be used to restore a worn-down surface. Hardfacing by arc welding is a surfacing operation to extend the service life of industrial components, preemptively on new components, or as part of a maintenance program. The result of significant savings in machine down time and production costs has meant that this process has been adopted across many industries such as steel, cement, mining, petrochemical, power, sugar cane and food. According to the results of an experimental study, the shielded metal arc welding and the gas metal arc welding hardfacing processes were effective in reducing the wear on the mouldboard ploughshare. With the shielded metal arc welding and gas metal arc welding hardfacing processes, the life span of the ploughshare was increased approximately 2 times [1].
Extensive work in research has resulted in the development of a wide range of alloys and welding procedures. The optimum alloy selection is made considering the component service conditions and feedback of the service performance.
For each industrial application and wear phenomena, there is a welding electrode to provide wear resistance.
Hardfacing can be deposited by various welding methods:
Commonly applied materials include cobalt-based alloys (such as stellite), nickel-based alloys, chromium carbide alloys and NOREM. Hardfacing is sometimes followed by hot stamping to refinish the part or add color or instructional information to the part. Foils or films can be used for a metallic look or other protection.


Goldens' Foundry

Goldens' Foundry and Machine Co. is a privately held ductile iron and gray iron foundry with headquarters in Columbus, Georgia and additional facilities in Cordele, Georgia in the United States. It has operated continuously since 1882. Goldens' provides castings to a variety of industries, including agricultural, construction, power transmission, defense, and large vehicles.
Operations.
Goldens' Foundry began operations in Columbus, Georgia in 1882 as Goldens' Brothers, founded by 32-year-old Theodore Earnest "Theo" Golden and 24-year-old John Poitivent "Porter" Golden. At the beginning of 1889, Goldens' Brothers was incorporated, with the financial support of Abraham Illges, and renamed Goldens' Foundry and Machine Company.
Goldens' is still owned and operated by descendants of the original three founders. George Golden Boyd, Sr., president and CEO, and George Golden Boyd, Jr., vice president of sales, continue to lead the family-run company to this day.
The foundry went through numerous upgrades, growing into a facility. With integrated core, molding, cleaning, and machining, and finishing facilities under one roof, Goldens' is able to provide a single-source resource to casting consumers.
Goldens' employs more than 200 skilled workers at their Columbus location, and approximately 100 at their operation in Cordele.
Quality Assurance
Goldens' utilizes numerous techniques to ensure quality is maintained at both facilities. The company is ISO 9001-2015 certified by Lloyd's. Lean manufacturing principles are also in place throughout the facility, and 5S standards are in place in each department.
Columbus casting facilities.
In Columbus, Casting operations in Goldens’ are supported by four Brown-Boveri coreless induction furnaces, coupled with 1200°F (650°C) preheating, and a comprehensive core shop employing isocure, shell and no-bake (air set). Steel and quality scrap are purchased from a variety of sources.
Large casting facility.
Goldens’ Large Casting Facility utilizes a Heinrich Wagner Sinto automated molding machine. Using this (48x48 18/18) high pressure machine, ductile iron and gray iron casting capability includes the cost efficient manufacture of large castings. The Sinto incorporates the Seiatsu blow squeeze process, and provides opportunity to produce short run and high-volume orders.
The goal with a tight-flask machine such as this is to create near net-shape castings, reducing the need for machining and other processing operations.
Centrifugal castings.
Goldens' utilizes a specific centrifugal cast operation for adding iron liners to steel drums. In Goldens’ centrifugal casting process, molten iron is poured into a hollow cylindrical mold spinning on a horizontal or vertical axis at speeds generating 40 to 70 Gs of centrifugal force. This force distributes the molten metal, promotes directional solidification, and improves casting integrity by forcing impurities to the inside surface.
Centrifugal casting at Goldens' is designed for specific product applications, as opposed to other foundries strictly devoted to the centrifugal process, such as steel pipe foundries. The centrifugal casting process was added in the late 1990s as a complement to the green sand mold processes already in place.
No bake molding.
Goldens' added a fourth molding line, a no-bake sand operation in 2000. The manual molding operation allows production of much larger castings than the Sinto cope and drag machine, and is primarily utilized for Goldens' power transmission operations. This consists primarily of sheaves, pulleys, and sprockets.
Cordele casting facilities.
Goldens' new second facility comprises the largest step in expanding output in the company's 125-year history. The facility, built in 2001, houses a brand new Savelli cope and drag (28x36’ 12/12) molding line with automatic core setter to create small to medium-sized ductile and gray iron castings.
Although not as fast as many vertically parted molding machines, the Savelli is capable of making ~120 molds an hour. The new machine, with the expanded resources it provides, more than doubles the capacity of Goldens' casting production.
The facility also includes cleaning, finishing, and machining centers.
The building has previously housed two other foundries, Georgia Ductile and Wescast - Cordele. Both were foundries focused on supplying automotive parts for the US car industry.
Operations at the new Goldens' facility began in May 2007.
Machining operations.
Goldens' machining facilities handle most operations their customers need. The operations primarily consist of turning, milling, and drilling operations, although operators perform a limited number of threading, painting, tapping, and sub-assembly operations.
The Columbus machining facility is larger than the Cordele facility, having been there since the late 1800s. The Columbus machining facility includes a larger variety of machines as well, while the Cordele facility currently only maintains horizontal milling and drilling machines.
The Columbus machining center uses horizontal milling and drilling machines with table sizes ranging from 400mm2 to 630mm2. Vertical machines range from 20" x 39.5" to 22" x 44".
Industries served.
Goldens' serve a variety of industries, such as construction machinery, pumps and compressors, petroleum, mechanical power transmission, highway and off-highway trucks, farm machinery and equipment, and medical/surgical equipment. Goldens' utilizes both gray iron and ductile iron technology.
References.
 Goldens' Foundry and Machine Co. website
 The American Foundry Society


Take-back system

A take-back system or simply takeback is one of the primary channels of waste collection, especially for e-waste, besides municipal sites. Take-back is the idea that manufacturers and sellers "take back" the products that are at the end of their lives. Take-back is aimed to reduce a business' environmental impacts on the earth and also increase efficiency and lower costs for their business models. "Take-back regulations have targeted a wide array of products including packaging, batteries, automobiles, and electronics" and economic value can be found from recycling or re-manufacturing such products. "The programs benefit municipalities by lowering their overall waste disposal costs and reducing the burden on landfill sites". Although for certain companies, the take-back system is mandatory under legislation, many do it voluntarily.
Take-back can be split up into:
It can be further split into two types:
Recycling.
One major option of the take-back system includes store retailers or producers taking back the products that have been distributed to their consumers in order to recycle the materials of these products. The take-back system encourages businesses to redesign their products into ones that are easily recyclable, reducing the burden that virgin materials have on the environment for the present and the future. This also gives companies an alternative supply of raw minerals.
Re-manufacturing.
The other major option of the take-back system includes the store retailers or producers taking back their products in order to create new ones. This process uses the older products in order to restore it into products that are of the same quality as the new ones. By this process, companies save up to 85% of energy that would have been used to manufacture brand new products.
Economic effect.
The take-back system has shown economic effects for many companies that have adapted it. An example is Xerox, a company that has saved over $200 million from their take-back program in a year alone. The system encourages companies to create products that are easy to dissemble and re-manufacture in order to cut costs and generate revenue through taking back older products. In this way, companies can use older products that would have otherwise been thrown away in order to renovate them, allowing for them to be sold again just as Sprint has, in order to save over a billion dollars. In Wisconsin, the development of a take-back system created many new jobs, started a few companies, and had brought revenue from e-waste processing.
Environmental impact.
The take-back system provides a more environmentally friendly system for those that inherit it. The system gives the responsibility of handling waste to the producer, meaning that they are to guarantee that their products are dealt with when they are at the end of their lives. By taking old products back, companies reduce their environmental footprint on the world as their products are influenced to become more easily recyclable. The system influences companies to redesign their products in ways that are more cost-effective when they recycle, reuse, or re-manufacture their products. Policies of the system can require companies into using a certain amount of recycled material in their products, which reduces the amount of recovered materials that end up in landfills or incineration.
Circular economy.
The take-back system can be a main component to the business model that is called the circular economy. The circular economy is a plan for a business or company that aims to use and reduce their waste in order to become sustainable on their own. The take-back system allows for this model to work as it allows companies to recycle old products in order to become more environmentally friendly, where materials are used from these old products in order to use as resources and encourage sustainability. Not only that, but for most companies, the take-back system shows to be a more cost-effective system as it effectively minimizes waste management costs.
Implementation of take-back systems.
Collection.
Due to a high cost in recycling but low amount of customer incentive, companies and countries refrain from adapting a take-back system. To fix this, e-waste could be taken back by the producers for donations, for re-manufacturing, or for upgrades.
Waste regulation legislation and government help.
Without legislation, a prominent take-back system cannot be achieved because current e-waste regulation systems are "limited to private recycling of high-value waste with only limited consumer participation". Rules and regulations that would incentive and fix issues regarding to the dumping electronic waste into landfills and prevent the illegal exportation of electronic waste are important to achieve success in e-waste management. The government would need to support it by giving incentives and the correct infrastructure in order to create such a system.
Initiatives.
"Initiatives refer to programs or schemes required to promote effective collection, recycling and disposal of e-waste". Through these incentives, the government and producers of waste must promote e-waste management on their own by giving effort in collecting e-waste to recycle, renew, or reuse it.
Awareness and responsibility.
Consumers of the products must become aware to how managing their waste affects the environment and the lack of programs that help teach these aspects show to be big barriers to the effective management of waste. To manage the waste properly, consumers must begin to show responsibility in bringing in their e-waste while companies such as the producers of these products must be responsible for taking it back and dealing with it.
Germany's take-back system.
Germany had set in put a packaging ordinance on June 12, 1991. "It specifies mandatory quotas for recycling for glass, paper/paperboard/carton, tin plate, aluminum, plastic, and composites". The responsibility for handling waste was put onto the manufacturer and distributor. As a result of the ordinance, "in 1993, the beginning of the mandatory quotas, compared to 1992, there were 500,000 fewer tons of packaging" and "From 1993 to 1994, paper packaging recycling increased from 55% to 70.6%". The system showed to be a success, as it reduced waste and redesigned packaging to be more environmentally friendly simply from integrating a version of the take-back system.
Issues.
While the take-back system aims to create more eco-friendly businesses, there are reasons why it does not profoundly exist today. The main reason for this is the lack of incentives. Being that there are products such as cars and computers that are unappealing to transport, the consumer finds it troubling and unappealing to bring these products back. Also, since many consumers see refurbished products as inferior and do not trust them, it is unappealing for companies to re-manufacture their own products for reselling purposes and thus cannot profit from it. Without the appropriate subsidies, in some cases it becomes more beneficial for a company to use virgin materials as opposed to recycling methods as it is cheaper, swaying some away from the take-back system.


Monocrystalline whisker

A monocrystalline whisker is a filament of material that is structured as a single, defect-free crystal. Some typical whisker materials are graphite, alumina, iron, silicon carbide and silicon. Single-crystal whiskers of these (and some other) materials are known for having very high tensile strength (on the order of 10–20 GPa). Whiskers are used in some composites, but large-scale fabrication of defect-free whiskers is very difficult.
Prior to the discovery of carbon nanotubes, single-crystal whiskers had the highest tensile strength of any materials known, and were featured regularly in science fiction as materials for fabrication of space elevators, arcologies, and other large structures. Despite showing great promise for a range of applications, their usage has been hindered by concerns over their effects on health when inhaled.


Hot runner

A hot runner system is an assembly of heated components used in plastic injection molds that inject molten plastic into the cavities of the mold. (The cavities are the part of the mold shaped like the parts to be produced.)
By contrast, a cold runner is simply a channel formed between the two halves of the mold, for the purpose of carrying plastic from the injection molding machine nozzle to the cavities. Each time the mold opens to eject the newly formed plastic parts, the material in the runner is ejected as well, resulting in waste. A hot runner system usually includes a heated manifold and a number of heated nozzles. The main task of the manifold is to distribute the plastic entering the mold to the various nozzles which then meter it precisely to the injection points in the cavities.
Hot runner advantages.
Hot runner systems were first developed and came into sporadic use in the early 60s with generally negative results. They gained popularity in the 80s and 90s as technological advancements allowed improved reliability and the escalation of plastic materials prices made hot runner systems more desirable and cost effective. Hot runners are fairly complicated systems, they have to maintain the plastic material within them heated uniformly, while the rest of the injection mold is being cooled in order to solidify the product quickly. For this reason they are usually assembled from components pre manufactured by specialized companies.
A hot runner controller is a temperature controller used to control the temperature in the hot runner. This helps create the most consistent part(s).
Hot runners usually make the mold more expensive to manufacture and run, but allow savings by reducing plastic waste and by reducing the cycle time. (do not have to wait until the conventional runners freeze).


1971–72 European Cup Winners' Cup

The 1971–72 season of the European Cup Winners' Cup football club tournament was won by Rangers, who defeated Dynamo Moscow in the final.
Preliminary round.
Second leg.
"4–4 on aggregate; Austria Wien won on away goals."
"Hibernians won 3–2 on aggregate."
First round.
Second leg.
"Barcelona won 7–1 on aggregate."
"Steaua București won 1–0 on aggregate."
"Liverpool won 3–2 on aggregate".
"Bayern Munich won 7–1 on aggregate."
"Torino won 5–0 on aggregate."
"Austria Wien won 2–1 on aggregate".
"Rangers won 2–1 on aggregate."
"Sporting CP won 7–0 on aggregate".
"Åtvidaberg won 5–4 on aggregate".
"Chelsea won 21–0 on aggregate".
"Beerschot won 8–0 on aggregate".
"2–2 on aggregate; BFC Dynamo won 5–4 on penalties."
"Sparta won 3–1 on aggregate".
"Red Star Belgrade won 8–4 on aggregate".
"Eskişehirspor won 4–0 on aggregate".
"Dynamo Moscow won 3–2 on aggregate".
Second round.
1The second leg was originally 3–2 to Sporting after 90 minutes, and 4–3 to Sporting after extra time. The referee erroneously ordered a penalty shoot-out which Sporting won 3–0; UEFA later ruled that Rangers had won on away goals.
Second leg.
"Steaua București won 3–1 on aggregate."
"Torino won 1–0 on aggregate."
"6–6 on aggregate; Rangers won on away goals."
"BFC Dynamo won 6−2 on aggregate."
Quarter-finals.
Second leg.
"1–1 on aggregate; Bayern Munich won on away goals."
"Rangers won 2–1 on aggregate."
"BFC Dynamo won 4−2 on aggregate."
Semi-finals.
Second leg.
"Rangers won 3–1 on aggregate."
"2–2 on aggregate; Dynamo Moscow won 4–1 on penalties."


Laser polishing

Laser polishing, also referred to as laser re-melting, is a type of micro-melting process employed for improving surface quality of materials. As opposed to other conventional polishing processes, this process does not involve removal of materials from the workpiece surface. In this process, the laser is made incident on the workpiece to melt the surface till a certain depth, thus enabling subsequent betterment of surface parameters due to re-solidification of the melted material.
Laser Polishing can be done at two levels - micro and macro levels. The workpiece material can be any metal or metals alloys, and can also be used to polish certain ceramics and glass.
Principle and mechanism.
The aim of this process lies in melting a thin layer of the workpiece surface to reduce the average height of the peaks found on the surface asperities. The melting depth is strictly restricted to a certain degree of the asperity height to prevent any major microstructural changes deep in the workpiece material. This is hugely affected by the type of laser radiation, i.e. pulsed-radiation or continuous radiation, as well as the laser parameters, viz. laser power, feed rate or scanning velocity, laser beam diameter, and distance between source (or precisely laser focal point) and workpiece surface.
This process is widely researched for the application of surface reduction techniques on various materials. The two most general mechanisms are identified as Shallow Surface Melt (SSM) and Surface Over Melt (SOM).
Shallow Surface Melt (SSM).
Literature defines SSM region is formed due to dynamic behavior of the high-temperature metal liquid which is forced into micro-asperities essentially filling up the valleys present on the surface. The depth of the melted material is typically "less" than the peak-valley distance which can be affected by the laser parameters. The cited SEM image shows a clearly distinguishable laser polished surface without showing major side effects on the surrounding material, and can be used as a reference for understanding SSM mechanism.
Surface Over Melt (SOM).
Increasing the energy density of the laser beam after a certain level will change how the melt-pool, or the melted material will behave. With gradual increase in the melt-pool thickness, it will exceed the peak-valley distance (or the asperity height) thus converting the entire metal surface into a melt-pool. Higher densities of the laser causes the molten material to be pulled away from the solidifying front, thus forming ripples on the metal surface.
Thus, laser polishing with this mechanism requires extensive study of the effect of the laser parameters to reduce the waviness on the final polished surface.
Mechanical properties of laser polished components.
Since the workpiece surface is exposed to high temperature which establishes a huge thermal gradient along its cross-section, there are a few changes at the micro-structural level due to the material behavior at the surface. However, majority of the literature reports show little change in the overall material properties of the entire workpiece.
Surface morphology and microstructure.
The laser polished surface has a huge improvement in terms of average surface roughness of the worked material. This can be attributed to uniform distribution of the melt-pool during rapid solidification, due to presence of laser pressure, gravity and surface tension. The treated layer is divided into 3 major zones: the re-melted layer, the heat affected zone and the original workpiece material. The near consistent re-melted layer has finer grains compared to rest of the material because of high cooling rate. This reduction in size from original can be explained as a result of "grain boundary pinning" due to presence of already present or fresh precipitates in the melted material. The fresh precipitates may sprout from the material matrix or maybe induced from surrounding environment.
Going down the material, there is the heat affected zone, which is not exposed to the laser beam, but is affected by the melt-pool formed on the surface. The grain sizes are coarser than the re-melted surface layer, but not as large as the original grain size that are found by going further down the material (typically in additively manufactured workpiece).
Tensile properties.
The polished surface has a significant increase in tensile strength, but the total elongation (till failure) reduces. As a case study, consider a polymer-metal composite with aluminum fibers and PLA as the matrix. The cited study shows an increase in tensile strength from 41.01 MPa to 50.47 MPa with a reduced maximum elongation from an initial 60.6% to 33.2%. This can be explained as the result of densification and improved adhesion between the matrix and fiber components. The outcome therefore is increased rigidity and reduced ductility material at the polished surface.
For this specific case, the workpiece is fabricated with Fused Deposition Modelling (FDM), an additive manufacturing method. Typically, all the additively manufactured components have defects throughout their matrix, viz. gas porosity, gap between deposited layers, inconsistent lamination of the deposited layers and low adhesion among layers. All of the aforementioned terms have related or unrelated reasons of formation which can be studied in depth, but are beyond scope of this summary. These defects become the failure sources or origin of damage induced in the composite. Due to laser polishing, the failure behavior of the composite changes because of combined elastoplastic behavior of the newly polished fiber and matrix at the workpiece surface. Furthermore, since melted surface material flows from peak to unfilled valleys, many defects are removed. This also causes re-bonding of the matrix-matrix as well as matrix-fiber essentially improving the tensile strength as well as dynamic mechanical properties by creating a much denser structure.
This can be mathematically explained by rule of mixtures, by assuming constant strain for matrix and continuous fiber composite and evaluating the tensile strength for different stages found in a composite stress-strain curve
Other improvements can be seen on the polished surface are increased micro-hardness, wear resistance and corrosion resistance.
Fracture behavior.
Depending on the material being polished the fracture mechanism vary vastly for pure metals, non-metals, alloys, polymers, ceramics, amorphous solids and composites. All of them show improved fracture resistance post laser polishing because of reduced defects and increased resistance to crack propagation. However, this performance is not universal, it is also affected by presence of defects within the unaffected workpiece material.
The improved fracture behavior can be quantified by defining the critical stress intensity factor (formula_1). Theoretically, this value is achieved when the nominal applied stress is equal to the crack propagation stress, and is calculated taking into fact Griffith criteria. The final derived equation for a plane stress condition is given by a square root of product of the material stiffness (formula_2) and the material toughness ( formula_3). As evident, with increase in material stiffness, the polished surface is bound to have increased toughness.
A more in-depth study reveals role of more than just material stiffness in increase of the fracture resistance of the laser treated material. Multiple sources have described the effect of strain hardening (induced compression due to dislocation motion at elevated temperatures) and phase transformation within the material.
Consider another case study of a silicon nitride engineering ceramic. The result of this study documents the change in surface hardness, surface crack length and the surface formula_4 (mode-1 formula_1) by using the Vickers indentation technique(s). The increase in surface hardness and formula_4 factor can be related to the induced residual compressive stress due to motion of dislocations at the elevated temperatures during the laser polishing process. These compressive stresses act against the externally applied tension, thus needing a certain threshold value in addition to the fracture stress (or crack propagation stress) to completely overcome the opposing stresses before crack initiation. Other observations include a reduction of crack length by 37% in the laser polished Si3N4, and induced anisotopy, which is further discussed in the cited reference.


Rubber pad forming

Rubber pad forming (RPF) is a metalworking process where sheet metal is pressed between a die and a rubber block, made of polyurethane. Under pressure, the rubber and sheet metal are driven into the die and conform to its shape, forming the part. The rubber pads can have a general purpose shape, like a membrane. Alternatively, they can be machined in the shape of die or punch.
Rubber pad forming is a deep drawing technique that is ideally suited for the production of small and medium-sized series. Deep drawing makes it possible to deform sheet metal in two directions, which offers great benefits in terms of function integration, weight reduction, cleanability and such.
The disadvantage of regular deep drawing is that expensive tools consisting of an upper and lower mold are needed. Once these tools have been made, the variable costs are low, which makes regular deep drawing very suitable for large and very large numbers of products.
Technique.
In the rubber pad forming process only a milled lower die is required on which a metal plate is placed. Afterwards, the shape of the lower die is pressed in the plate with the rubber mold. In most cases, the contour, hole patterns and the like will be cut with a 3D laser cutter.
The simplicity of the rubber press tool causes tooling costs to be around 85 to 90% lower than those of regular deep drawing while the variable costs are higher. This combination makes rubber pad pressing very suitable for smaller and medium-sized series (up to 5,000-10,000 pieces per year), even though traditional cutting, lace, welding, finishing etc. is used more due to the unfamiliarity with rubber pad forming.

380 Ton Rubber Pad Press
Rubber pad forming has been used in production lines for many years. Up to 60% of all sheet metal parts in the aerospace industry are fabricated using this process.
The most relevant applications are indeed in the aerospace field. It is frequently used in prototyping shops and for the production of kitchenware. For a decade, rubber pad pressing has developed greatly into a widely used technology for many industrial applications.
Pressing power.
Enormous pressing forces are required for the rubber presses to work. In the Netherlands there are several rubber pad presses, of which the largest one has a press force of no less than 8,000 tons with a maximum surface area of 1.10x2.20m, these presses are used for very diverse industrial applications.
Worldwide, presses are in use up to about 14,000 tonnes.
Pros and cons.
In summary, the benefits of rubber pad pressing are:
And the disadvantages:
Definition.
Rubber pad forming can be accomplished in many different ways, and as technology has advanced, so have the applications for this simple process. In general, an elastic upper die, usually made of rubber, is connected to a hydraulic press. A rigid lower die, often called a form block, provides the mold for the sheeted metal to be formed to. Because the upper (male) die can be used with separate lower (female) dies, the process is relatively cheap and flexible. The worked metal is not worn as quickly as in more conventional processes such as deep drawing, however, rubber pads exert less pressure in the same circumstances as non-elastic parts, which may lead to less definition in forming, and rubber pads wear more quickly than steel parts.
The Guerin process.
The Guerin process, also called Guerin Stamping, is a manufacturing process used in the shaping of sheet metals. It is the oldest and most basic of the production rubber-pad forming processes. It was developed in the late 1930s by Henry Guerin, an employee of the Douglas Aircraft Co. in California. Thereafter, it was used extensively by all major aircraft manufacturers to shape the many complex shapes inherent in the design of aircraft.


Component engineering

Component engineering is an engineering discipline primarily used to ensure the suitability and testability of suitable components required to manufacture a larger product.
The term combines two ideas:
Component designer engineers design, oversee the production, and test components for machines used in many different industries, from aviation to manufacturing, IT, software, telecommunications, and many more.
To make machine parts that are reliable and effective, they are involved in various stages of production, starting from research and product development, to compliance and design, or might work on testing and installing components.