CBN tooling solutions for powder metallurgy clutch discs
A. Reasons why powder metallurgical parts are difficult to machine
Porosity can lead to:
Non-abrasive cutting edges;
High cutting edge temperatures, causing wear and distortion of inserts;
The intrinsic porous structure causes an increase in surface area, which allows oxidation or carbonisation during heat treatment, and these oxides and carbides are very hard and wear resistant;
Due to the presence of pores, the hardness values fluctuate over a small area. While the measured macro hardness is HRC 20-35, the hardness of the particles that make up the part can be as high as HRC 60 and these hard particles can lead to severe and sharp edge wear;
Many powder metallurgical parts are harder and stronger after heat treatment.
There may be inclusions in the part. These problems can be referred to as difficult machining of powder metallurgical parts.
B. Tool materials for machining powder metallurgical parts
If processing powder metallurgy parts on the CNC lathe above, generally will choose ceramic tools and cubic boron nitride tools, carbide tools are generally not wear-resistant. Ceramic tools and cubic boron nitride tools in the processing of powder metallurgy, generally finishing processes, customers can be based on the actual situation and the economics of the use of tools specific choice, such as a large margin, the use of cubic boron nitride tools large margin processing powder metallurgy parts.
C. Case study of powder metallurgy processing with CBN for Wiese tools