436 BELL SYSTEM TECHNICAL JOURNAL 



in developing products from powder metals that fall into class 6 above. 

 There are many instances where automatic pressing and continuous anneal- 

 ing operations on small parts in quantity have made the process econom- 

 ically feasible for competition with the standard casting method. There 

 are many factors involved in determining whether parts should be thus 

 fabricated, and these will be described at greater length in the section on 

 limitations of the powder method. 



With the advent of increased production for war purposes, the powder 

 process has, in many instances, been utilized to insure a steady supply of 

 many small parts needed for ordnance. The use of powder metallurgy 

 has released machines and mechanics for other types of work, and because 

 of the speed and ease of setting up for production, it has often been possible 

 for suppliers of small parts to adhere to schedules they could not otherwise 

 meet^^. In addition, because of the low metal loss connected with the powder 

 process, there is considerable saving of scarce or strategic material. 



To the six general classes of materials listed above, can then be added 

 another class that can best be described as utilitarian. The powder method 

 has been used as an expedient to supplement and extend normal pro- 

 duction methods without regard to cost. However, it has often proved 

 itself to be economically competitive, and in many cases, has effected consid- 

 erable savings over normal production methods^'. 



The intensified war production schedules have opened the larger field that 

 has been long predicted by powder metallurgists, that of using the powder 

 method to displace the conventional methods of making many parts not 

 in the classification of specialty products. Even under the abnormal war 

 conditions, however, there are indications that progress along these fines 

 will not be rapid and the early promise shown has not been completely 

 reafized. Progress has been made, nevertheless, but many of the devel- 

 opments and products are known only to those workers actually engaged 

 in producing parts for the wartime program, and only when the story of 

 the progress made can be told, will complete evaluation of the process be 

 possible. 



It is the befief of some metaUurgists, as yet realized commercially with 

 only a few special items, that parts can eventually be prepared by powder 

 methods with properties superior to those obtained by melting, casting, 

 and working techniques. At least one investigator reasoned that, since 

 sintered tungsten is stronger than fused tungsten, iron or steel prepared 

 similarly should show the same superiority^^. Actual studies conducted 

 using relatively high compacting pressures indicate that both iron and 

 steel can be prepared by powder methods with tensile properties better 

 than those obtained on the some materials made by fusion processes. 



