Cold formings

Cold compressors Cold flow Cold forming Cold gas ColdGR-S... 

Cold Forming. Some ABS grades have ductihty and toughness such that sheet can be cold formed from blanks 0.13—6.4 mm thick using standard metal-working techniques. Up to 45% diameter reduction is possible on the first draw subsequent redraws can yield 35%. Either aqueous or nonaqueous lubrication is required. More details are available in Reference 147. 

Conventional thermoforming of sheet and film is appHcable to the production of skylights, radomes, signs, curved wiadshields, prototype production of body parts for automobiles, skimohiles, boats, etc. Because BPA polycarbonate is malleable, it can be cold-formed like metal, and may be cold-roUed, stamped, or forged. 

Tees Tees may be cast, forged, or hot- or cold-formed from short pieces of pipe. Though it is impossible to have the same flow simultaneously through all three end connections, it is not economical to produce or stock the great variety of tees which accurate sizing of end connections requires. It is customary to stock only tees with the two end (run) connections of the same size and the branch connection either of the same size as the run connections or one, two, or three sizes smaller. Adjacent reducers or reducing elbow fittings are used for other size reductions. Branch connections (see subsection Joints ) are often more economical than tees, particularly when the ratio of branch to run is small. 

Virtuallv evety alloy system has its specific environment conditions which will prodiice stress-corrosion cracking, and the time of exposure required to produce failure will vary from minutes to years. Typical examples include cracking of cold-formed brass in ammonia environments, cracking of austenitic stainless steels in the presence of chlorides, cracking of Monel in hydrofluosihcic acid, and caustic embrittlement cracking of steel in caustic solutions. 

Steel Carbon steel is the most common, cheapest, and most versatile metal used in industry. It has excellent ductility, permitting many cold-forming operations. Steel is also very weldable. 

PROCESS MATERIAL. IMPACT EXTRUSION COLD FORMING COLD EXTRUSION SHEET METALWORK MACHINING POWDER METAL SINTERING... 

BODY COLD FORMING STEEL IMPACT EXTRUSION... 

The body is impact extruded from a cold forming steel. The characteristic dimension to be analysed in the tolerance stack is the base thickness of 3 mm (on a 020 mm bore) and this dimension has been assigned a tolerance of 0.02 mm. 

MAGNETIC POLE COLD FORMING STEEL MACHINED... 

Provided due care is taken with respect to predrying and to crazing tendencies, polycarbonates may also be thermoformed, used for fluidised bed coating and machined and cemented. Like metals, but unlike most thermoplastics, polycarbonates may be cold formed by punching and cold rolling. Cold rolling can in fact improve the impact resistance of the resin. 

Cold forming Machining Fusion welding Inert gas xy gos arc Resistance spot welding Protective anodising... 

Pseudomorphism has less desirable consequences, and usually means are sought to suppress it. If the substrate has been scratched, ground or abrasively polished, or if it has been cold rolled or cold formed, the surface is left in a peculiar state. Cold working reduces the surface grain size, and produces deformed, shattered and partly reoriented metal. It may produce microcrevices between the deformed grains, and, with some processes, non-metallic impurities and oxides are embedded in the surface. The disturbed state of the substrate is copied by a pseudomorphic electrodeposit with several consequences (Fig. 12.7). One is aesthetic it has often been noted that almost invisible abrasion of the substrate develops as more prominent... 

Some ductile plastics, such as PC and ABS, can be fabricated like metals with punching and cold-forming techniques. These processing techniques are analogous to the hardness tests in that a rigid indentor is pressed into a sheet of a less-rigid plastic. 

Solid-Phase Forming (Cold Forming) of Plastics , PLASTEC Rept R42 (1972) 36) A.F. 

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