A computer controlled optical pin polishing machine

A typical optical mold manufacturing process consists of turning or grinding of stainless steel molds and a manual polishing procedure to remove tool marks and other surface artifacts. This process can be time consuming and labor intensive. Recently, there are several computer controlled polishing systems being introduced to the industry for improving the polishing process such as magnetorhelogical finishing and precession polishing. However, these processes either have limitations on material selection or on cycle times. Polishing pressure is one of the most important parameters to control during a polishing process. There are designs with different mechanisms to maintain a constant polishing pressure from pressure-sensitive polishing arm to weight balance method. In this research program an innovative method was introduced to monitor and control the polishing pressure. A precision in line torque sensor is used to couple the polishing head and the motor. The primary feedback on the polishing axis is tool position. Once the polishing tool makes contact with the mold surface then the torque signal will be utilized as the primary feedback signal for minor adjustment on the polishing tool vertical position for maintaining constant pressure. A process using the pin polisher with different size diamond pastes was also developed.