Friction coefficients of 3D printed tool surfaces

Abstract

Abstract The clamp tools used in forming processes require high coefficient of friction (COF) to impart rigid clamping during the process. The mating surfaces of clamp tools are conventionally machined using CNC machines. Recently introduced metal-based Additive Manufacturing (AM) machines can 3D-print the clamp tools and produce tool surfaces with significantly high COF as compared to CNC processes. An accurate assessment of COF values of clamp tools surfaces is necessary for both numerical and finite element (FE) based modelling and simulation of forming processes. In this research, an investigation is made to determine the precise COF values of as-is surfaces of clamp tools 3D printed by Selective Laser Melting (SLM). The COFs of 3D printed as-is surfaces are compared with corresponding CNC-machined surfaces. The design and FE stress analysis of the clamp tool is carried out in the software Autodesk Inventor. The clamp tool is 3D-printed by a SLM machine using ultra-high strength maraging grade tool steel - X3NiCoTi1895 (1.2709). The surface roughness of both additively manufactured and CNC-machined surfaces is determined and the relationship between surface roughness and COFs of additively manufactured clamp tools is discussed. It is an application based research particularly oriented for metal bending and forming industries. In such industrial processes, the precise values of COF of clamp tools substantially assist to accurately predict the process outcome through modelling and simulation techniques.