ABSTRACT
A brief review of traditional manufacturing processes is presented to gain an understanding of the differences in approach between sustainable and environmentally benign manufacturing. A large number of processes are used in manufacturing operations, some of which can be categorized as follows:
1. Casting and foundry processes. Molten metal, plastic, or glass is cast into a mold and solidified into shape. The design considerations in casting can be noted as
a. Do not have thick sections at the bottom of a sand casting. b. Do not use sharp corners. Sharp corners can cause cracking and tearing at corners. c. If the fillet is too large, voids can occur. d. Do not have two walls crossing, offset the crossing. e. Keep all sections as uniform as possible. f. Core diameters should be no less than the wall thickness. g. If possible, hollow out solids. h. Avoid large flats because they warp. i. Include draft angles to allow pattern/casting to be removed. j. Use simple part shapes. k. Avoid the need for cores; however, if they are used, join cores to ensure accurate placement. l. Avoid undercuts. m. Avoid rapid wall thickness changes. n. Consider machining requirements. 2. Deformation processes. Typical deformation processes are forging, rolling, extrusion, and wire
drawing. In all these processes, metal is usually deformed either hot or cold to give it improved properties and to change its shape. Sheet metal forming is a special category in which deformation occurs in a two-dimensional stress state. The design considerations in deformation processes can be listed as
Forging design considerations: a. Use shapes that would occur as a result of die forging. b. Avoid undercuts. c. Provide tapers. d. Avoid rapid thickness changes.
