Abstract
The theoretical movements required for the various moving tool elements during the pressing cycle are examined for several typical component sections. These theoretical movements are then compared with the actual movements of the moving tool elements in various types of tooling. The conclusion is reached that the conventional tool designs vary greatly from the ideal in many ways, permitting uncontrolled lateral powder movement during pressing and causing excessive density variation in the pressed compact.
Three major problems are apparent:
(1) The use of a solid die for pressing compacts with varying section thicknesses results in an “average” die movement that is always too great for the thicker section and too small for the thinner section.
(2) The double function of the floating punch, which takes vertical pressure on its horizontal face while its vertical face acts as a die, presents a very difficult problem. The floating punch movement, controlled by its horizontal face, is always greater than the correct movement required to give minimum density variation in the portion of the compact formed by the vertical surface of the punch.
(3) The various types of support used for floating punches rarely provide the correct timing, sufficient maximum load, or progressively increasing resistance essential to ensure equal density distribution within the powder during the pressing operation.
Suggestions for tooling, designed to solve some of these problems, are discussed.
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