Effect of Process Parameters on Burrs Produced in Micromilling of a Thin Nitinol Foil

Abstract

This paper examines the formation of burrs in micromilling of a thin nickel–titanium alloy (nitinol) foil used in implantable biomedical device applications. The paper analyzes the effects of key micromilling process parameters such as spindle speed, feed, tool wear, backing material, and adhesive used to attach the foil to the backing material on the burr height. It is found that burr height is larger on the downmilling side for grooves cut with a worn tool at high feeds, low spindle speeds with a softer backing material, and a weaker adhesive bond. Some important interaction effects of these factors are also studied. The study also shows that the mechanics of burr formation in such thin materials depends on whether the mode of cutting is dominated by tearing or chip formation, which is a function of the feed rate. A kinematic model to predict burr widths is developed and verified through experiments.