Tuesday, August 31, 2010

Metal Production Technology

Classification
Primary forming, reshaping, cutting, joining, coating, modification of properties.
The production of a workpiece involves transforming a blank or raw piece from its original state to a finished state by changing its shape or the properties of the material in a series of steps. When no further changes have to be made, it is known as a finished piece or finished part.

The classification of production processes starts from the concept of coherence of the material particles, or coherence of the structural elements.

Creating coherence: primary forming, giving shape.
Primary forming consists of making a solid body out of formless material, included in this category are casting of metals, ceramics and plastics, pressing metal powders and subsequently sintering them, pressing synthetic resins, the production of workpieces by electrolytic deposition.

Maintaining coherence: Reshaping, reorienting material particles.
Reshaping consists of changing the shape of a solid body without adding or removing material (plastic transformation). This cathegory includes remodelling by pressure (extrusion molding, forging, rolling) by tension and compression (deep drawing, wire drawing) by tensile re-formation (stretch forming) and by bending.

Changing the properties of the material by reorienting the material particles. This include processes in which the internal structure of the material is changed , e.g. tempering, hardening, solid, rolling, magnetisation.

Reducing coherence: cutting elimination of particles
Cutting is a means of reshaping a solid body by overcoming its coherence. Distinctions are made between: dividing e.g cutting off, incising, tearing: chip removal (machining), e.g. turning, drilling, grinding, filling, sawing, wearing off material by heat (e.g. torch cutting); separation of previously joined workpieces, e.g. unscrewing, squeezing out, cleaning of workpieces by brushing, sand blasting, washing, pickling.

This group also includes the elimination of material particles, e.g. decarburising steel.
Joining consist of bringing together workpieces by combining (insertion and suspension), by adjusting and fitting (wedging, screwing, shrinking), by primary shaping (iremolding), deforming (folding together, wrapping, riveting) by material bonding (welding, soldering, use of adhesives).

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