Improvement of the forming ability in microgroove molding by ultrasonic vibration

Microgrooves with a pitch at wave length level are increasingly needed in the optical system. Conventional microgroove molding is able to fabricate the microgrooves, but the forming accuracy is low because of the incomplete filling of the material in the cavity of microgroove mold, and surface defect or internal defect occurs easily because the air trapped during the pressing. In this research, ultrasonic vibration was applied to the improvement of the forming ability of the molding process for microgrooves. Basic experiments were carried out to test the effects of ultrasonic vibration on friction force decrease and material flow ability improvement. An ultrasonic assisted molding machine was developed and used to fabricate microgrooves on methacrylic resin surface by using the Nickel Phosphorous (Ni-P) mold. Form accuracy and surface quality of microgrooves were confirmed to be improved by comparing the ultrasonic assisted molding with the conventional molding.