A two-station embossing process for rapid fabrication of surface microstructures on thermoplastic polymers

An embossing strategy involving a hot station and a cold station for sequentially heating and cooling the embossing tool was investigated to reduce cycle times in hot embossing polymer microstructures. Experimental studies showed that aluminum stamps with a thickness of 1.4 mm can be rapidly heated from room temperature to 200 degrees C in 3 s using contact heating against a hot station at 250 degrees C. Microchannels and microlenses were successfully embossed onto high-density polyethylene and acrylonitrile-butadiene-styrene substrates using a heating time less than 3 s and a total cycle time around 10 s. The two-station embossing process for the microlens was also numerically studied. The simulated filling behavior agreed with the experimental observation and the predicted thermal and deformation history of the polymer offered a good explanation on the experimentally observed process characteristics.