Post 257 – by Gautam Shah
Main Objectives of Materials Processing:
- Shape and size formation
- Alteration and induction of properties
- Endowing finishes
1 SHAPE AND SIZE FORMATION
Body forming processes change the dimensional format of the material through phase-change of the material (solid to liquid to gas, or vice versa), within the same material phase (heat treatments, hot and cold working, and through mechanical work like mixing, stirring), and through material compositions (structuring, assembly).
Grains or dust mixed with a binder material can be cast into solids, or melted-fused as alloy, or sintered to a ceramic. Solids can be rolled into sheets or melt-spun into fibres, ground to powders, or drawn into wires. Fibres and wires are woven into fabric sheets.
- Solid forming: Forging, beating, pressing, rolling, drawing, casting, extrusion, moulding.
- Sheet forming: Bending, punching, stamping, cutting, seaming, forming, moulding.
- Linear forming: Drawing, spinning, entwining, weaving.
- Grain forming: Blowing or granulation, chopping, grinding.
Shaping processes can also be classed as:
1a Flow processes: casting, moulding, extruding, drawing, rolling, forging, hammering, beating, powder-technology, material deposition, stamping, punching, pressing, bending, folding, seaming.
1b Additive processes: lamination, crystal growth, foaming (lower phase material dispersion in a higher phase material), plating, cladding, mounting, joining, material deposition, fabrication, joining, supporting, holding, keying, positioning, plugging, arranging.
1c Reducing processes: cutting, chopping, sizing, splicing, scooping, drilling, boring, machining, planning, chiselling, chipping, grinding, rubbing, sand blasting, cleaning, washing, melting, dissolving.
1d Other forming processes: spinning, weaving, knitting.
2 ALTERATION AND INDUCTION OF PROPERTIES
Alteration and Induction of properties cause a change in the engineering or structural quality of the material, frequently accompanied by the modification of the surface characteristics. The alteration processes are also designed to regain the lost or the reduced properties during other processing.
2a Heat treatments: boiling, liquidizing, melting, softening, sintering, baking, drying, fusing, welding, soldering, forging, annealing, heating, hardening, crystal forming, blowing.
2b Non heat treatments: magnetizing, static discharging, infection proofing, cleaning, washing, earthing, wetting, drying, stretching, strenting, stressing, compressing, stretching (tensile), twisting, filling.
2c Material applications: coatings, depositions, claddings, Panellings, enamelling, inlaying, gilding, printing, moisture proofing, fuming.
2d Non material processes: embossing, engraving, polishing, burring, charring, burnishing, chasing, buffing.
2e Chemical treatments: dyeing, bleaching, etching.
3 ENDOWING FINISHES
Finishes are created: By altering the surface properties of the materials at a raw material stage and also after the formation of the object, By reforming the objects, and By applying other materials at a raw material stage or at an object formation stage.
The need for a peculiar finish could be varied, but essentially for: Imparting specific sensorial characteristics, for survival of the object in an environment, for changing the structural properties, as an aid in material processing and forming operations, for storage and handling of the raw materials or components, and for receiving the next treatment.
3a Processes for Natural Surface Finishes: Natural Finishes result due to many different factors, such as: Elemental conditions of formation, subsequent responses like weathering, cognitive affectations, and later, natural or man-made interventions (angle of cut, tools and techniques used, etc.).
Natural surface finishes have three main cognitive affectations: Colour, Pattern and Texture. The colours are of original formation, subsequent weathering, readjustment of stresses, or induced by physical and chemical changes. The patterns result from the stresses, mixing of constituents, weathering, and the varied reactivity of different parts and constituents. Patterns also result from granular or fibrous orientation, method of cut, cyclic nature of growth, formation of residual products, deposition of contaminants, and tools-techniques of handling and processing. Textures primarily result from the degree of homogeneity, angle of cut, differential weathering, and various formative processes.
3b Processes for Manufactured Surface Finishes: Manufactured Surface Finishes result at three levels: Raw material stage, Product formation stage, and later, through Application of surface finish on completion of the system. In an integrated production setup all three could be a single stage or plant process, but in most other fabrication shops only the last two processes are combined. For a site fabricated systems like buildings, the last process, i.e. surface finish application, is a distinct process as it is carried out at a site. Manufactured surface finishes as a result are of two categories: Plant based and Site-based systems. Though lot of preparatory work may occur in the industrial plant for the site-based surface finish application. Products fully surface finished in industrial plants require very careful handling (transportation, loading, storage, delivery and positioning), and so may carry protective but removable coatings or shields.