Performance analysis of coated tools in real-life industrial experiments using statistical techniques

PVD hard coatings are being used extensively and with considerable claimed performance benefits in many metal-cutting industrial applications. However, the use of coated tooling in forming/forging operations has been relatively limited and the performance benefits under-exploited. Work was therefore carried out to determine the influences of various production factors on the lifetime of a cold forming tool used in an industrial company. Experimental design and statistical techniques were used for data analysis, including analysis of variance (ANOVA) with Taguchi contribution ratios, Weibull analysis, Scatter diagrams, and box and response plots. The applicability of these techniques with regard to the cold form tools used in this study are discussed and then generalised for the assessment of other applications. The results show that only a combination of factors (surface finish and surface coating) gave a significant improvement in tool life. Only by using a Weibull analysis were the performance benefits from the experiment quantifiable, due to a change in the population distribution as well as a shift in the population mean between the uncoated tools and the best-performing coated and polished tools.