Tool life and surface integrity when hard turning stainless steel using wiper coated carbide tool

Master's Thesis from the year 2008 in the subject Engineering - Mechanical Engineering, grade: Satisfactory, University College of Technology and Innovation, Malaysia (Universiti Teknologi Malaysia), language: English, abstract: The feasibility of implementing hard turning partially depends on the performance of the cutting tool in generating the required machined parts. Since process efficiency is a continuous pursue, there is always a need of having inexpensive cutting tools able to deliver the expected quality of machined surfaces and having reasonable life times. For this purpose, the selection of cutting conditions and its performance are important. In this study, a carbide tool with TiAlN coating is proposed as the low cost alternative for performing moderate range of hard turning. Specifically, a coated carbide tool with wiper geometry was used to machine hardened martensitic stainless steel (47 - 48 HRC). The tool's performance is evaluated based on its tool life and the resulting surface finish when hard turning at various cutting speeds (100, 130, and 170 m/min) and feeds (0.125, 0.16, 0.2, and 0.25 mm/rev) and at constant depth of cut of 0.4 mm under dry condition. Further observation was made on the worn tool, the machined surface, and the generated chip. The wiper coated carbide tool lasts mostly beyond 2 minutes and even reaches a maximum of almost 18 minutes of service life time.
Combination of abrasion and diffusion are suggested to be the main wear mechanisms of the cutting tool. The resulting surface finish is very fine, being entirely finer than 0.8 mim in Ra which is one level better than the theoretically expected value. Empirical models are developed to quantify the effect of cutting speed and feed to the tool life and Ra. Further observation at the optimum process
parameter combination, for example the lowest cutting speed-lowest feed, reveals minimum machining-induced surface microstruct