Orthogonal Cutting Study of the Micro-Cutting Thin Workpiece

With a broader intention of producing thin sheet embossing molds, results from investigations in orthogonal cutting of thin workpieces are presented here. Challenges in machining thin workpieces are many: residual stress effects, fixturing challenges, and substrate effects. Aluminum alloy Al6061-T6 workpiece fixture using an adhesive is orthogonally cut with a single crystal diamond tool. We study trends in cutting forces, understand to what level of thickness we can machine the workpiece down to and in what the form the adhesive fails. Two types of workpiese-adhesive anomalies were noticed. One is the detachment of the thin workpiece by peel-off and the other one is where the workpiece did not get detached but the final width of the workpiece was non-uniform. We then use a validated finite element machining model to understand the stresses in the workpiece when it is thick and when machined to thin condition, effect of the adhesive itself and also the effect of adhesive thickness. Simulations show that the stress induced by the cutting process at the bottom of the workpiece is higher for the thinner workpiece (40 μm) compare to a thicker workpiece (400 μm) especially at the tool entrance region for adhesive thicknesses of 30 μm and 100 μm. Hence a thinner workpiece is more susceptible to failure by adhesive peeling.