An analysis of through-hole punching in PMMA with varied process parameters

Abstract

The ability to combine through-hole punching with a surface patterning during microembossing would greatly enhance the production of a variety of microfluidic devices. In support of that goal, a series of theoretical simulations and physical tests were performed to investigate the effect of clearance, shear speed and temperature in creating through-holes. A better understanding of the effects of these parameters in through-hole punching has useful implications in the development of better tools for hot embossing. Theoretical simulations modeling the punch and die mechanics for various punch sizes and clearances were performed using ADINA finite element analysis (FEA) software; similar simulations were done for a straight shearing situation for comparison. A special straight-line punch and die set with a movable was then machined for use with an existing hot-embossing machine. Tests were done while varying the temperature of the sample, the clearance of the shear and the shear speed. From the finite element analysis, we gathered data about the shear stress distribution in the samples during the shearing process. The physical experiments gave us information about the peak stress for each test, allowing for some quantitative analysis. The parts were also assessed qualitatively under 10x magnification and classified accordingly. Ultimately, we were able to see some signs of shear quality degradation with increased clearance, but the differences were less pronounced at small clearances (25 microns or less).