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During machining processes, some metal is removed from the piece. To compensate for this, a machining allowance (additional material some times referred to as green) should be given in the casting. [7] the amount of finish allowance depends on the material of the casting, size of casting, volume of production, method of molding, etc.
Plastic drawing, sometimes referred to as cold drawing, is the same process as used on metal bars, applied to plastics. [8] Plastic drawing is primarily used in manufacturing plastic fibers. The process was discovered by Julian W. Hill in 1930 while trying to make fibers from an early polyester. [9]
The "f" came from "finish" in the sense of "machine finish" as opposed to raw stock/casting/forging. Later the ASA convened upon a letter V (specifically a sans-serif V) touching the surface. Soon this evolved into the "check mark" sign with accompanying number that tells the reader a max roughness value (RMS, microinches or micrometres) for ...
When part definition is defined mathematically via a solid model, the assertion that one cannot interrogate the model—the direct analog of "scaling the drawing"—becomes ridiculous; because when part definition is defined this way, it is not possible for a drawing or model to be "not to scale". A 2D pencil drawing can be inaccurately ...
The machining allowance varies drastically from one process to another. Sand castings generally have a rough surface finish, therefore need a greater machining allowance, whereas die casting has a very fine surface finish, which may not need any machining tolerance. Also, the draft may provide enough of a machining allowance to begin with. [28]
Centrifugal casting (industrial) Continuous casting; Die casting; Evaporative-pattern casting. Full-mold casting; Lost-foam casting; Investment casting (Lost-wax casting) Countergravity casting [1] Lost-foam casting; Low pressure die casting; Permanent mold casting; Plastic mold casting; Resin casting; Sand casting; Shell molding; Slush casting ...
Kits fall into two categories, machined and unmachined kits. Unmachined kits usually consist of drawings, castings, stock metal, and possibly fasteners and other fixings necessary to complete the model. They require machining facilities to complete and often also require additional components and raw materials.
Casting is most often used for making complex shapes that would be otherwise difficult or uneconomical to make by other methods. Heavy equipment like machine tool beds, ships' propellers, etc. can be cast easily in the required size, rather than fabricating by joining several small pieces. [1] Casting is a 7,000-year-old process.