Frictional behaviour of CaCO3 powder compacts

Abstract

During powder compaction processes friction has an influence on the final shape and properties of components. It is therefore important to understand how the friction influences the compaction process. Since detailed friction measurements of the powder compact–tool interface are rare, simulation models of the powder compaction process often involve a more accurate description of the frictional behaviour. This limits the accuracy of the simulated results. More accurate numerical models can give improved results, especially in regards to the evolution of density and its distribution within the powder compacts. This study is as a step towards more advanced friction models for powder compaction simulations. A universal tribometer has been used to investigate the frictional behaviour of contact interfaces between a carbide counter surface and CaCO 3 powder compacts with different densities. Both static and dynamic frictional properties were measured in a variety of conditions to build a fundamental foundation for friction modelling in powder compaction simulations. The results show that increasing the powder compact density decreases the dynamic friction coefficient but that the static friction coefficient remains fairly constant. The measured friction coefficient can be used to improve the simulation of a powder compact process. Also investigated is the change in friction coefficient that occurs in the compaction process when the surfaces are worn such that loose powder appears in the interface between the tool and the powder compact. This behaviour is important to take into account to accurately describe the compaction process. During powder compaction processes friction has an influence on the components final shape and properties. A universal tribometer was used to investigate the frictional behaviour of contact interfaces between a carbide counter surface and CaCO 3 powder compacts. The results show that increasing the powder compact density decreases the dynamic friction coefficient but that the static friction coefficient remains constant. ► A study of frictional behaviour of CaCO 3 powder mix. ► Dynamic and powder sprinkled samples (static) investigated. ► The dynamic friction coefficient decreases with increasing density. ► Static friction is independent of the powder compact's density. ► A density dependent mathematical function for the dynamic friction coefficient has been found.