Mixing powders for die pressing of Powder Metallurgy parts
The advantages of mixing powders
- Use directly
- Customized to service to optimise performance
- Increase productivity, reduce scrap rates & reduce environmental impact
- Increased green strength without impairing other properties such as density or lubricity
- Efficient use of materials and energy
- Due to the high green strength, the machining time is shortened, the tool life of the machining tool is longer, and the scrap rate is greatly reduced
- Access to a wide range of different alloys and additives
To introduce alloying element additions in a homogeneous form
Die pressing feedstocks generally consist of elemental mixes in order to maintain as high level of compressibility as possible. Using this approach means that the compressibility is controlled by that of the soft, annealed base iron powder (most commonly iron). Use of a fully pre-alloyed powder would mean that the initial particle hardness and work hardening rate would both be increased by the alloying additions and compressibility therefore reduced.
To incorporate a pressing lubricant
Popular lubricants are stearic acid, stearin, metallic stearates or other organic compound of a waxy nature. The purposes of adding the lubricant are to reduce friction (and therefore even out density variations) during compaction, to reduce ejection forces and to minimise the tendency for ejection cracking in the compact.