The processing technology of thin-walled-open slot parts in powder metallurgy

Powder Metallurgy is one of the main technologies for the production of gearbox interlock block. The interlock block has the characteristics of low stiffness, open slot and thin wall（3.5 mm）. Parts are prone to deformation in the powder metallurgy production process, resulting in instability of the final product size. Through research and verification, this paper find out the main causes of deformation in the production process, and the process is optimized through the following 3 aspects. The forming die completed the “opening” to make the part “whole” to avoid the deformation caused by uneven thermal stress during sintering. At the same time the die adopt the form of “powder escape slot” to adjust the density of each step to ensure the overall density. The sandblasting was replaced with polishing, which reduced the influence of the uneven stress caused by sandblasting and led to the instability of machining size, and determined the optimal polishing time of 5 min. When machining slotting, rough machining reserved 0.3 mm wall thickness for finish machining, which solved the problem of deformation caused by clamping. Through the above improvement, the open slot size CPK is increased from 0.8 to 2.5, meeting the production requirement of CPK>1.33.