Turning of tool steel : Study on the effect of insert grade and entering angle on tool life

Abstract: PrimeTurning™ is a new turning technology, which consists of tools and programming method. By using this method, it has been demonstrated that higher material removal rates and flexibility in turning can be obtained.  The New Product Industrialisation department at AB Sandvik Coromant works with development of production processes and improvements in current processes.Machining tests are carried out in order to improve production performance, and find optimised solutions.  In this master thesis work, the effect of insert grades and entering angles on wear and tool life while machining hardened tool steel has been studied. Machining experiments have been carried out to analyse wear and tool life by using the PrimeTurning™ method.Two approaches of experimental design have been investigated, and a suitable design is selected for conducting the experiments.  The performance of these insert grades and tool holders (κ=21° and κ=25°) has been compared to each other and the existing production scenario, and a recommendation is made regarding insert grade,tool holder and cutting parameter selection for machining hardened tool steel using PrimeTurning™. The wear analysis has been performed by using a stereo microscope coupled with an image processing software to measure the flank wear length. Flank wear, flaking and chipping have been observed as the major wear types.  As a result, it has been identified that the insert grade GXXC, coupled with the tailor-made tool holder performs significantly better than the currently used insert and tool holder in production. A substantial increase in tool life increase is observed, even when machining at a higher Material Removal Rate of 29%. This would result in a significant increase productivity, if the results can be reproduced in production.