Microdrilling of Nitinol

Nitinol, a shape memory alloy, has seen increased use in a variety of industries, especially the medical industry due to its biocompatibility. The growing demand for product miniaturization combined with these newfound uses has accelerated the need for scientific research into microdrilling. Conventional microdrilling in particular shows promise for its ability to produce accurate, high quality holes in a cost efficient manner when compared to other technologies.

This research investigated the minimization of tool wear when drilling with ?127?m uncoated tungsten carbide tools, as well as with AlTiN/Si3N4 and AlTiN coated tools in minimum quantity lubrication condition. The proper and optimal coatings protected the tool surface and reduced tool wear at higher cutting speeds but were ineffective at lower cutting speeds. Additionally, control of built up edge formation proved critical in decreasing wear, reducing drill wandering and improving hole quality.

Finite element analysis was used with the orthogonal cutting model to predict tool fracture as a function of cutting speed and chip load. The method provided reasonable estimates of cutting and axial forces involved in the microdrilling process, but failed to predict the formation of built up edge and its effect.