Investigation of cutting forces and machinability during milling of corrosion-resistant powder steel produced by laser metal deposition

Abstract

Introduction. Additive manufacturing technologies for the production of geometrically approximate workpieces require post-processing. This applies to the use of cutting tools in milling operations when machining critical surfaces. The latter are specified strict requirements to accuracy of linear and angular dimensions and quality of the surface layer. An urgent task remains to increase machining productivity when recording cutting forces and surface roughness to develop technological recommendations. Purpose of work: experimental determination of cutting modes providing the highest productivity when milling LMD-workpieces (Laser Metal Deposition) made of steel 0.12-Cr18-Ni10-Ti (AISI 321) by carbide end mill, while maintaining the milling cutter operability and required roughness. The properties and microstructure of the specimens along and across the build direction are investigated. The influence of feed (when the mill moves across and along the build direction), depth and width of milling, speed on the components of the cutting force and roughness of the machined surfaces during counter milling of LMD-workpieces made of steel 0.12-Cr18-Ni10-Ti (AISI 321) with end mill made of H10F carbide with a diameter of 12 mm without wear-resistant coating is established and formalized. The research methods are the dynamic measurement of all three components of the cutting force using a three-component dynamometer and the measurement of roughness with a profilometer. The condition and microgeometry of the cutting edges were monitored before and after milling using scanning optical and scanning electron microscopy. Results and Discussion. The difference in cutting forces depending on the milling pattern (along and across the build direction) was shown. Studies showed that the milling depth and cutting speed have little effect on the lateral and axial components of the cutting force. The feed force increases significantly with increasing depth of cut, especially when feeding across the specimen build direction. It is found that all three components of the cutting force are directly proportional to the value of the minute feed. The equations for calculating all three components of the cutting force with a change in the minute feed are obtained.