Application of powder metallurgy on machine tools


Powder metallurgy was started when osram was produced in 1920’s, while the powder metallurgy industry in China was firstly appeared after 1950’s and developed rapidly as an independent industrial department. In recent years, powder metallurgy that is used in producing structural parts has achieved fast development, which is replacing some of the commonly used structural steel and has been widely used in automobiles, motorcycles, agricultural machinery production and other fields. However, its application on machine tool industry started a little late.

Powder metallurgy is not only a kind of special parts manufacturing forming method, but also a kind of chipless forming process, in which the metal powders or the metal powders and nonmetal powders are pressed and formed in the die cavity before being mixed according to the required proportion, afterwards, they are made into powder metallurgy mechanical parts via sintering and finishing. This method can save materials and machining time as well as reduce machining equipments and cost. Therefore, powder metallurgy parts have wide prospects in the application on machine tool industry, which can decrease cost and increase benefit for the enterprise production as well as applied in the material property, parts precision, heat treatment and other aspects.

To research the application feasibility of powder metallurgy parts according to the material property

Structural steel (carbon steel or the alloy steel) is a kind of metal material that frequently used in the machine tool components, which often requires good synthesized mechanical properties (both have enough strength and tenacity). Iron base powder metallurgy materials that are widely used at present, such as cemented iron, sintered carbon steel, sintered alloy steel and so on, of which the mechanical properties have close or equivalent property of medium carbon steel and low alloy steel, therefore, it will not be a problem to choose the parts material for the machine tool components.

Certainly, there is still a gap between the mechanical property of powder metallurgy parts and casting and press forging. Considering that machine tools require higher transmission accuracy and less noise than automobiles, motorcycles and other manufacturing industries, it can be seen that powder metallurgy parts cannot be used in the important transmission and high speed parts of machine tools according to the practical use, however, they can be used in some auxiliary feed irregular parts that are not important as these kinds of parts have complex shapes, which will spend many cutting machining time and have low material utilization rate. Besides, parts that made by powder metallurgy can realize the aim of less cutting or no cutting.

Analysis on the economic accuracy of powder metallurgy parts

The accuracy requirement of powder metallurgy parts depends on the working conditions. As we  know that the precision of machine tool components are often in the middle level or above the middle level except for the leading parts that have extremely high precision, therefore, no sizing is needed if we use the powder metallurgy parts or obtain the dimensional precision via simple sizing, thus it will reduce the requirements on die materials and save cost.

By using powder metallurgy parts, the difficulties that existed in the fitting work caused by too much machining time and different dimensional deviation can be overcome and realize chipless forming as well as achieve consistent dimension accuracy, besides, it can be directly used for assemble due to the good universality and interchangeability; the other prominent advantage of powder metallurgy part is that it has lower price than machining parts. Therefore, it is economic to use powder metallurgy parts when the requirements on parts precision are appropriate instead of blindly pursue high precision and avoid reducing the precision requirements too low to display the superiority of powder metallurgy process.