A Critical Survey of Powder Metallurgy and its Application in Ordnance Design.

The usefulness of metal powder parts depends primarily upon their correct design and application in structures where high physical properties are not essential to proper functioning. The size of powder compacts is limited by the capacities of automatic presses--usually 100,000 p.s.i. - and the pressure which must be applied in order to form pieces of adequate strength. For most ferrous-base materials the compressing area of powder parts is limited to approximately one square inch. The economics of die costs, press and furnace operation, and for moderately large pieces the cost of the metal powders must be considered in the application of the powder metallurgy method to the production of any part. Pressing and sintering cannot compete in many instances with automatic screw machine production, cutting sections from extruded bar stock, or precision die casting. It is a method which becomes practical only when large quantities of small parts are involved or where a great deal of difficult machine work will be eliminated by its employment. The principal application of powder metallurgy in Ordnance design is found in parts of ammunition and small arms components which are not highly stressed . At the present time, no high strength metal powder materials are being manufactured on a commercial scale even though test bars of high mechanical strength have been produced in research laboratories.