4.3 - Production Processes< Seed Factories
Factories in general produce a set of products which fall into one or more industries. Making these products involves a set of steps comprising a Process Flow connecting factory inputs to outputs. The connections between individual process steps may be a simple linear sequence, or have more complex parallel and looping paths. Individual processes require suitable system elements to operate, including hardware tools and equipment, software, facilities, information, and people with suitable skills.
For seed factories, which evolve by making more equipment for themselves, part of the output loops back as new system elements. The process flow is thus not fixed for long periods of time, as it is for more traditional factories. There are many possible growth paths from starter sets to a desired mature factory capacity. The goal of engineering is to find the best such path, and design the individual elements required to follow it. To ensure the best path is chosen, all feasible alternatives should be considered, at least at first, before narrowing the choices to the best few. In this section we therefore try to list all known and possible future process steps. From the set of all possible processes, we can eliminate the ones that do not apply at all, or are not feasible to use for the given application. Feasibility depends on factors like scale, cost, technical readiness, and available inputs, which may render an option impractical. The remaining process steps can then be combined into process flows, and the flows into a growth path from seed to mature factory. Alternate design options then use different process steps, flows, and growth paths. These are evaluated against goals and requirements to narrow the choices and select the best remaining ones.
The process list below is a work in progress, so there are likely a number of missing items. There is a large literature on manufacturing processes, and we will not repeat all that information here. Instead we supply links or pointers when available, and the name of a process can otherwise be used to search for more information. In addition to being a catalog for designing a starter set and later expansion paths, this list can be used for analysis of the Universal Factory concept described in section 3.0. A Universal Factory should be capable of eventually performing any of the listed processes in order to make any possible product.
The list is organized according to the general order of production steps, from extracting raw materials to assembly and construction of finished products. These steps are further divided by types and sub-types. We used the following Wikipedia articles as sources for the early draft: List of Manufacturing Processes, Chemical Process, and Unit Operation. We are using the Handbook of Manufacturing Processes (Bralla, 2007) to add more details, and some additional items were added from other sources.
This is extracting inorganic materials from solid natural sources. It includes:
This is extracting liquids and gases from natural sources. It includes:
This is extracting organic materials from natural sources. It does not include agriculture, which is under materials processes because it is artificial, rather than extracting from nature. Organic Extraction includes:
Plant Extraction, including collecting fruits, nuts, herbs, and other plant products.
Timber Extraction, when collected from natural rather than managed sources.
Materials begin in a "raw" state, as extracted from natural sources or returned for recycling from artificial sources. Materials processes convert raw materials to "finished" materials. These can either be used as is, such as gasoline as a fuel, or converted to finished products by fabrication and assembly. An example of a finished material is dry lumber, which can be cut and assembled into furniture or structures. Materials processing involves some set of physical, chemical, and electromagnetic Unit Operations, which are the basic elements of a process. Operations may be applied in series or in parallel. For example, boiling and reacting two chemicals may happen at the same time in one device.
Fluid flow processes: including storage in Tanks, transport by means of Piping, Valves, Compressors and Pumps, and control by Flow measurement. The various equipment elements are combined into fluid systems.
Heat transfer processes involving heating and cooling by radiation, convection, and conduction. They include Condensation, Liquefaction, Refrigeration,Boiling, and Evaporation, heating and baking in a Furnace, and Melting.
Mechanical processes include moving solids by Conveyors, Pneumatics or Material Handling. It includes modifying solids by Crushing, Pulverization, Milling, and Mulling. It also includes sorting and combining materials by Screening, Sieving, Flotation, Agitation, Mixing, and Fluidization
A reactor is a device where a chemical reaction occurs, which results in different chemical outputs than the than the reactant inputs. In formulating a chemical process, both the type of reactor and what reaction type(s) happen in it must be chosen. There are about ten million known chemical compounds, and therefore a multitude of specific chemical processes to produce them. Processes consist of a sequence of steps, which can be organized into a smaller list of reactors, and general and more specific reaction types which together perform a step. The following list of reactors and reactions is not comprehensive:
Reactors may be divided into batch and continuous flow types. They may have mixers, catalysts (which are not themselves changed like the reactants) or heating and cooling to create the right reaction conditions. The physical phase (solid, liquid, or gas) of the reactants and outputs may be the same (homogeneous) or different (heterogeneous), and there may be an interface across which heat or mass is transferred. Energy aside from the chemical reactions may be supplied in pressure, kinetic, or potential forms. These conditions affect the physical design of the reactor. The reaction phase types are: Homogeneous - involving liquid-liquid, and gas-gas chemistry, and Heterogeneous - involving gas-liquid, solid-liquid, gas-solid with catalyst, gas-solid without catalyst, solid-solid, and gas-liquid-solid (three phase) chemistry.
The state of the reactants and outputs may differ, yielding the following types of gas-solid reactions: (1) Solid + Gas → Solid + Gas, (2) Solid + Gas → Solid, (3) Solid → Gas + Solid, (4) Solid + Gas → Gas, (5) Solid → Gas, and (6) Gas → Solid + Gas. These various combinations of reactor conditions, plus energy to assist the reaction process, result in the following reactor types:
- Gas-Liquid Reactors - Bubble Columns, including Packed Bed and sectionalized; plate column, external- and internal-loop air-lift reactors, static mixer, and venturi scrubbers
- Liquid-Liquid Reactors - Spray column, packed extraction column, liquid-liquid adaptations of loop reactors, plate extraction column, and static mixers.
- Solid-Liquid Reactors - Fluidized-bed reactor, fixed-bed reactor
- Gas-Solid Catalytic Reactors - Fixed-bed reactors (multi-tubular and staged adiabatic), fluidized-bed reactors (bubbling bed, turbulent bed, fast, and
transport or pneumatic), radial flow reactor, gauze reactor
- Gas-Liquid-Solid Reactors - Fluidized-bed reactor, slurry reactor
Kinetic Energy - Single-stage and multistage Stirred-Tank Reactors, self-inducing reactor, jet-loop reactor, plunging- jet reactor, surface aerator
Potential Energy - Packed column, trickle-bed reactor, film reactors (falling film, agitated film, scraped/wiped film), rotating disk (or rotating packed-bed) reactor
Single Replacement (Substitution)
Double Replacement (Metathesis)
Specific Reaction TypesEdit
More specific reaction types include:
- Alkane Fusion
- Electrostatic Separation
- Magnetic Separation
- Electrolysis and Electrorefining
Fabrication, as the term is used for seed factories, is the conversion of finished materials into finished parts, without necessarily changing the material characteristics by the process types in the previous section. Originally, fabrication was more specific to Metal Fabrication, and the first three sub-headings here: Casting, Forming, and Machining, primarily relate to metal parts. The same processes can also be used for other sufficiently rigid materials, like plastics, glass, ceramics, and wood. The latter materials, and less rigid ones like fabrics and paper, have more specialized processes, which are listed afterwards.
Casting is the process of producing a desired shape by delivering a liquid material into a hollow cavity called a Mold, where it is allowed to solidify. For metals, the liquid state is typically reached by heating. For other materials, like epoxy, concrete, plaster, and clay, a liquid or soft state is obtained by mixing ingredients, which then harden or cure without high temperatures. In both cases, the mold is removed after the casting is complete, leaving a finished shape. The shape is often further processed by other processes like machining and grinding when higher accuracy is needed. A Foundry is a specialized workshop or factory for making metal castings. The casting processes listed below vary by types of mold, and how they are made and used.
- Melting & Pouring
Various types of Furnaces are used to melt metals and other materials which melt at high temperature, like glass. These include the Cupola, Electric Arc, Crucible, Reverberatory, Induction, and Open Hearth types. Some furnaces can be directly tapped to lead the melted material to the mold. More often it is transferred by a crucible or ladle designed to control the temperature and rate of pouring. Molds by their nature are closed and opaque, so methods like machine vision or weight are used to determine the right amount of material to fill the mold.
Sand casting uses sand plus a suitable bonding agent such as clay to form the mold. The mold shape is either produced by compacting the sand mix around models or Patterns of the desired part, or by directly carving the sand. Patterns must account for shrinkage as the casting solidifies and cools. Packing the sand, or Ramming is by various manual, machine, or kinetic methods. The molding sand is contained within a box or flask, and the container can be typically disassembled to remove the pattern, reassembled to do the casting, then taken apart again to remove the part. The sand mold is typically damaged during removal, sometimes intentionally by vibration. The sand is often recycled for additional castings.
Methods of sand casting include Green Sand, which is uncured before pouring in the hot liquid, and Dry Sand Casting, where the molded sand is dried or baked first. Refractory coatings can be applied to the mold surface, and thermoset additives and reinforcing bars to make it more rigid. This is more expensive than green sand, but has a better surface finish and can handle larger castings. Skin-dried molds only dry 6-25mm of the interior surface, which is faster than fully drying it. In Shell Molds the sand is mixed with thermoset plastic resin. The pattern is heated and inserted in a container of the sand mix, where the resin melts and sets the sand in a shell around the pattern, which are then separated. Since the pattern is only 5-10mm thick, the casting box is usually filled with a backing material for strength. Evaporative-Pattern Casting consists of Lost-Foam and Full-Mold types, which differ in using unbonded or green sand as backing. The pattern is made from foamed polystyrene, which is coated with permeable molding material by dipping, spraying, or brushing, then dried. This is placed in a box with the sand backing. The pattern vaporizes when the hot material is poured in. This method is suitable for complex castings and mass production, since the foamed patterns can themselves be made in a reusable mold. In Magnetic Molding, the foam pattern is surrounded by fine iron powder, which is magnetized to hold it in place while pouring. The heat conductivity produces finer-grained castings, and the iron is easily re-used. Additional sand casting methods include Vacuum, Cement-Sand, Loam, and Flaskless Molds, and the Antioch Process.
Cores are sections of a mold made separately from the main exterior sections. They are used whenever there is an undercut, opening, or hollow area in the casting that cannot be filled by packing sand around a pattern. They are made from sand with sufficient binders for handling and insertion in the mold box. Core-making includes the same types of steps in making the main mold sections, like baking, filing, sanding, and coatings for smoothness and heat resistance. Complex cores may be fastened or glued together from pieces, and if cantilevered, the core supported by Chaplets, which are metal pieces which later become integrated with the rest of the casting. For some shapes, a Cheek is used instead of a core. This is an additional section of mold and box, stacked with the two main sections.
- Other Expendable Molds
Ceramic Mold Casting is used when higher melting point materials are cast than sand can withstand. The ceramic is poured as a slurry around the pattern, and the pattern is removed before the mold completely hardens. It is then Fired like other ceramics in a furnace, and the casting poured while the mold is still hot. Firing is an irreversible change, and differential shrinkage on cooling or removal of the casting makes it difficult to reuse the mold. To reduce cost, the Ceramic Shell Process uses a facing layer of high temperature ceramic, with the balance of the mold filled with cheaper Fire Clay. Plaster Mold Casting uses a mix of water, Plaster of Paris, talc, and other ingredients which are poured around the pattern. After setting, the pattern is removed, and the mold baked to remove water of hydration, then molten material poured into the hot mold. This is suitable for lower melting point metals than sand casting.
This process uses reusable metal molds to produce multiple identical castings. Typically cast iron molds are used, with refractory coatings and graphite powder to enable separation of the casting. It is suitable for lower melting point alloys than the mold is made of. Sometimes graphite molds are used for high temperature alloys, but it is brittle and does not have a long life. Metal is not porous, so requires vent holes to release the air present before liquid is poured in. Complex cores are difficult, so this process is limited to simpler shapes. Filling the mold is by some combination of gravity, air pressure, and vacuum. These approaches can reduce Dross, oxidized impurities that can form from molten metals. Slush Casting allows a shell of material to solidify in the mold, and the rest poured out. This produces hollow castings with a good outside finish, but a rough interior. Pressed Casting involves partly filling the mold, then a closely fitting core is inserted, forcing the liquid into the remaining space. This produces a good finish on both inside and outside. Vacuum Casting is used to prevent atmospheric contamination and remove entrapped gases. The heating and pouring occur in a vacuum chamber.
True Centrifugal Casting uses rapid rotation of a simple mold, typically at 300-3000 rpm, to force the melt against the walls, producing a symmetric cylinder or ring. Impurities and voids are forced out of the casting. In Semicentrifugal Casting symmetrical circular parts like wheels and gear blanks are cast with more complex molds. Centrifuged Casting produces smaller intricate parts that are not circular. The forces provide pressure to completely fill the mold, where gravity alone is not sufficient. For high melting point products, the same mold materials are used as previously described. For low melting metals and thermoset plastics, Spin Casting uses vulcanized silicone or organic rubber molds, which can be used multiple times.
Die casting uses permanent molds called Dies, typically of hardened steel, where the melt is forced in under high pressure with a plunger, which is maintained until it solidifies. The molds are water cooled and lubricated, with two main halves and side cores if needed, which are mechanically activated for each casting cycle. After it hardens, pins eject the finished casting. Because the mold and filling equipment is complex, this process is suited to high volume production. Variations include High Pressure Die Casting, Low Pressure Die Casting, and Gravity Die Casting. In the Hot Chamber method, the plunger stays in contact with a vat of hot melt. In the Cold Chamber method, the plunger and chamber are in intermittent contact, which is more suited to higher melting materials. Trimming and grinding of excess material is often done immediately after the cast part is ejected, while still hot and relatively soft. If the part must be pressure-tight, impregnation and baking of a sealant may be done afterwards to fill any pores.
This is also known as Lost Wax Casting. An expendable pattern of wax, plastic, or frozen low temperature alloy is surrounded by a ceramic slurry. When this hardens, it is heated so the pattern melts out (i.e. is lost), leaving the desired cavity shape. Additional heating bakes out any residual material and fuses the ceramic. Melted material is then poured in to make the part, after which the mold is removed by breaking, blasting, jets, or chemicals. This method is suited to intricate, small, precise, high quality surface and strength parts. In the Flask Method, one or more patterns, plus filling leaders, are inserted in a container, which is then filled with slurry. After drying, the flask is inverted and heated, allowing the pattern to melt out, then further heated to fuse the mold. In the Shell Method, the pattern is dipped in slurry repeatedly, with each layer allowed to dry, building up a shell ~6 mm thick. This may be supported by cheaper backing material during casting.
This process produces long or continuous sections of product by filling an open-topped mold with melt material. The mold and feed rollers below it are water-cooled, and additional water sprays rapidly cool the melt. The solidifying melt continuously exits the bottom of the mold as more material is fed from the top. This process is suited to making large amounts of standard bar, tube, and strip shapes, but requires a high degree of control of the melt and solidification process.
Forming is the process of making parts and complete objects through mechanical deformation - changing the shape by the application of pressure. The pressure can be applied by devices like Rolling Mills, Power Hammers, and Machine Presses. Where casting is with materials in a liquid state that have no strength to resist shaping, forming uses solid materials with a Yield Point. When exceeded, the shape is permanently changed. Unlike other processes which add or remove material, forming does not change mass. Forming is most commonly applied to metals, but can be used on any material with suitable properties.
- Hot and Warm Forming
Hot and warm forming processes involve heating the workpiece to reduce the yield point. Hot forming is performed above the recrystallization temperature (about 60% of the melting point in Kelvin), and warm forming is between 30 and 60% of the melting point. Cold forming is below 30% of the melting point. The specific temperature required depends on the type of metal and the process being used.
Rolling in general passes stock between one or more pairs of rollers to reduce thickness and make it uniform by compression. Hot Rolling is used when the stock is thick and would otherwise require extreme forces. One or more passes may be needed, depending on thickness, adjusting roller spacing each time. Roller pairs may be oriented in different directions for multiple sides, and shaped rollers can produce specific profiles. Hot Drawing or Cupping makes cylinders with closed ends (cups) or tubes from flat stock, by pressing between one or more sets of Punches and Dies, depending on the depth and thickness needed. Extrusion forces a heated metal billet or ingot through a die opening with a ram, normally hydraulic, producing a constant cross-section. Indirect Extrustion reduces friction by moving the container and billet against the die and ram, which are hollow. The Sejournet Process allows extruding high melting materials by coating them with molten glass and/or phosphate. This reduces friction and insulates the equipment.
Forging uses more localized and higher pressures than the previous methods, typically by repeated impact, and fewer constraints on the shape from dies. For metals, the process can improve grain structure and other properties. Since the forces are local and nowadays mechanically amplified, forging can produce very large parts by shaping different sections in sequence. Smithing is the craft of metal shaping with hand tools, typically hammers, along with related tasks. It is very ancient, and developed numerous specialties according to the type of material and product. Blacksmiths, for example, work with iron and steel, heated in a Forge when required by the size of the part.
Drop forging raises and drops a powered flat or shaped hammer on the workpiece, which rests on a flat or shaped surface. The metal part deforms to adopt a matching shape. In the Open Die method the part is not confined, such as a flat hammer and a flat anvil. The part is free to move to all sides. In the Closed Die method, shaped cavities and hammers force the material into specific shapes. The die parts may be replaceable, held by larger and simpler supports. Hammers may use gravity, mechanical acceleration, air, steam, or hydraulics to achieve great impact forces. In Precision Forging the blank part and dies are carefully sized and shaped to produce a part that does not need much finishing. Press Forging applies a slower and longer pressure, usually hydraulic, to the blank than hammer methods. Metal flow is more uniform and yields better surface detail. Upset Forging shortens length and increases diameter using axial forces. Roll Forging uses powered rollers with shaped cavities to produce specific cross-sections. Ring Rolling is similar to the hot rolling mentioned earlier, except the part is ring-shaped rather than linear, and passes repeatedly through the same set of rollers. Piercing produces thick-walled seamless tubing by feeding a heated rod between two tapered and angled rollers, against a pointed mandrel.
Welded Pipe is made by roll forming a flat strip into a cylinder, and fusing the edges under pressure in a butt or lap joint. The joint must be hot enough to fuse. Creep Forming uses lower temperatures and stresses to gradually shape a part, while Hot Spinning applies point pressure to a rotating part against a mandrel. This is useful for symmetrical parts. In Isothermal Forging the part blank, hammer, and die are all the same temperature, to prevent heat loss in the part. Induction Forging heats a part from the inside, rather than from outside in a furnace. Various combinations of forging methods can be use at once or in series.
- Cold Forming
There are a number of Forming Processes done at cold (below 30% of melting point) or room temperatures. See also the Work Hardening Process list. These are commonly performed on sheet metal, since thicker metal requires too much force to shape cold, and other suitable thin materials.
Cold Rolling is a variation on rolling in general, where the material is at lower or room temperature. It can reduce thickness, improve surface finish and dimensional accuracy, and increase strength by work hardening. Cold materials have higher yield strengths than when hot, so this process is used for smaller size workpieces. Cold Drawing reduces size and can change shape by pulling the material through one or more tapered dies whose opening is smaller than the starting material. Lubrication and annealing between die passes assists in the process. Solid wire, bars, and rods are made with simple die openings. Tubing is made with a fixed mandrel in the middle of the die opening.
Shearing as a process is the cutting of relatively thin material between upper and lower sharp edged tools, whose force exceeds the strength of the material. Typically the tool clearance is 5-40% of the material thickness. Shears as a machine usually have a clamping device to hold down the material being cut to a fixed table. This keeps it from moving or being deformed by the cutting process. They also provide space for the cut-offs to fall away once separated. Squaring Shears have straight blades and can cut large metal sheets or plates with hydraulic pressure. The blades are slightly angled so the cutting action progresses from one side to the other, lowering the force needed. Alligator Shears operate like scissors by pivoting one blade against another, and are suited shapes like rods and bars rather than sheet. Since the force is at an angle, the material must be held in place so it does not slide. Rotary Shears use angled sharp rollers that move across the piece being cut. Nibbling makes a long cut by a series of overlapping holes or slits sheared in series. Roll Slitting divides sheets or coils into narrower pieces using circular knives rotating on powered arbors. This both cuts and feeds the material.
Stamping in general is a process that uses precision shaped forms, called punches and dies, which shape or cut metal by pressure. Devices range from manual hammers and die sets, up to large powered Stamping Presses. Lubricants protect the equipment and parts from damage, and ease material flow. A number of specific processes have been developed for different parts and materials:
Blanking cuts part blanks from a sheet with a punch and die set which shears the entire edge of the part at once. Steel Rule Die Blanking uses strips of hardened steel shaped to match a lower punch plate. Additional punches arranged on supporting backing plates can produce complex shapes with multiple openings. It is suited to cutting softer materials and thin metal sheets to limit the cutting force and wear. Dinking uses one-piece hollow knife-edged dies pressed or hammered against a soft block to not dull their edge. Cutoff and Parting sever a part from larger stock material. The latter differs in leaving a scrap piece. Punching (piercing) uses punch and die sets to create holes and edge notches in a part. Turret Punching moves the part, and a series of punches dies held in indexing turrets, to create complex shapes with multiple holes. It is used when the part is too large to make as a blank all at once, or the quantity does not justify making custom Tooling - the cutting tools, fixtures, jigs, and accessories used with production machines. Trimming is similar to blanking, except a semi-finished part is stamped with a punch and die set to remove excess scrap from the edges. Shaving is a secondary stamping after blanking or punching with closely fitting punch and die, to remove very small amounts of material and reach an exact size. Lancing only stamps a slit or cut, but does not sever scrap. It typically prepares for later bending steps. Fineblanking uses precisely controlled pressures, speeds, and multi-part punch and die sets to produce precision parts. Semi-Piercing uses a short punch stroke to offset, rather than completely sever a piece.
Bending deforms a flat piece around a straight axis, typically with a bending or press brake. The part is held in place between a die plate and clamping pad, while the punch rotates or descends. A stop or gage controls the width of the bent section. Various punch and die shapes can produce simple bends, vee, or rounded bends. A punch press can bend multiple sides of a part at once rather than cutting them, with suitably shaped sets. Thin sheet material can be formed into more complex shapes than simple cutting and bending can produce by using three-dimensional forming dies and punches. Rubber Pad Forming uses a polyurethane pad pressed against a stiff form block, shaping the part between them. The rubber distributes the pressure evenly across the part. The Guerin Process uses thick, soft rubber surrounded by strong walls. The vertical pressure is converted partly to horizontal as the rubber is squeezed. The Marform Process uses a deeper rubber pad and a spring or hydraulically supported holder plate. The plate move down relative to the form block as pressure is increased, allowing deeper shapes. Hydroforming and Verson-Wheelon methods use a rubber diaphragm backed by hydraulic fluid, but differ in using a moving ram or rubber pad and fixed form. Drop hammer forming is similar to drop forging mentioned above, except working cold material by repeated hammer strokes.
Drawing forms a recess more than half the width in depth, from sheet material using a lesser pressure holding the flat sheet, while a higher pressure punch forces the material into the die. The edges of both punch and die are rounded to allow flow from the sheet into the die, and for deeper parts the material is annealed between draws to prevent tearing. More complex shapes can be produced by multi-part punches that hold and shape in one operation, or by Redrawing in a series of steps, either direct (same direction) or reverse, with annealing as needed. Coining locally changes the thickness of flat material to conform to shaped dies, while confining it laterally. Since it is applied to the entire surface, rather then just the edges of a die, great force is required such as by drop hammer. Embossing differs in also offsetting material rather than just shaping in place.
There are several ways to reinforce an otherwise weak thin sheet. Flanging produces a bent edge on a sheet. If the edge is straight, then simple bending suffices. Curves or corners require more extensive forming with dies. Beading uses long narrow dies to create a trough, while Hemming and Seaming fold over an edge, or join two edges by folding. Tube beading forms a bead on tubing using rollers or expanding punches. When the edges are from different parts, it becomes an assembly process. Curling produces a rounded rather than flat-folded edge. Full circle edges require several die steps in sequence. Finishing operations on a rough part include Sizing in an accurate die, and Ironing a drawn part with a punch through a round-edged die to thin and smooth it.
--To Be Sorted--
- Tube end forming
- Roll bending
- Special purpose
- Honing (w:Sharpening)
- Finishing & w:industrial finishing
- w:Ultrasonic machining
- w:Electrical discharge
- w:Electron beam machining
- w:Electrochemical machining
- w:Laser cutting
Additive fabrication is the opposite of machining. Where machining produces a part by removing material, additive processes add material to make a part. It is also known as 3D Printing or Rapid Prototyping
- w:Selective laser sintering
- w:Fused deposition modeling
- w:Three dimensional printing
- w:Laminated object manufacturing
- w:Laser engineered net shaping
- Slush or slurry
- w:Plastics (see also w:rapid prototyping)
- w:Shrink fitting
- w:Shrink wrapping
- Plastic mold
Paper & PrintingEdit
Assembly & Construction ProcessesEdit
Assembly generally refers to combining finished parts and materials into complete finished products. Construction generally refers to assembly of non-mobile products such as buildings, and includes any work on the land for the construction site. There is no hard line between these two main types. For example, Modular buildings may be partially assembled in a factory, and then the sections joined at the construction site. Therefore the processes listed below can be used for both smaller, transportable products and larger, stationary, ones.
- Oxyfuel gas
- w:Projection welding
- w:Upset welding
- w:Percussion (manufacturing)
- w:Solid state welding
- w:Electron beam welding
- w:Laser welding
- w:Adhesive bonding (incomplete)
- wood and metal
- (By material fastened)
- Machine (Metal)
- Wood Screws
- (By slot type)
- Phillips (“Plus sign” in Canada)
- Straight (“Minus sign in Canada)
- (By shape)
- Round head
- Flat head
- Box head
- Nut and bolts
- w:Press fitting