1. Davorin Kramer, University of Ljubljana, Faculty of Mechanical Engineering, Slovenia
In order to reduce the consumption of cutting fluids, the trend in machining is moving towards dry or near-dry cutting. But even with the most advanced tool materials and coatings, it seems that lubricants in the case of hard- to-cut materials such as hardened steels used for moulds, Cr-Co alloys used for prosthesis, Ti-based, and Ni-based alloys used in gas turbines and in the aerospace industry cannot be completely avoided. With the intention to keep increasing the machining performance, different assistance methods have been developed to replace the ‘‘conventional process’’. One of them is high-pressure jet assisted machining (HPJAM), which aims at upgrading conventional machining using the mechanical and thermal properties of a high-pressure jet of water or emulsion directed into the cutting zone. HPJAM is starting to be established as a method for substantial increase of removal rate and productivity in the metal cutting industry. Cooling lubrication with high pressures in turning operations is an effective method for providing higher productivity, reducing temperature in the cutting zone and improving chip control depending on the pressure and flow rate of the fluid jet.
The aim of this paper is to compare the capabilities of dry, conventional flooding and HPJAM of hard-to-machine materials. The performances of different cutting conditions are compared on the basis of chip breakability, technological windows which yield particular operational ranges, cooling lubrication efficiency, tool wear, and cutting forces, as well as machining costs.
Key words: high pressure cooling, machinability, hard-to-machine materials
Mehanika i konstrukcije