Design of a low-cost fiber optical occlusion based automatic tool setter for micro milling machine

The objective of this research is to create an inexpensive, automated tool setter to reduce the overall tool set up time. The project focused on addressing the tool setting in the Z-axis (spindle axis), which is needed for each tool change, and accounts for majority of the total tool setting time. A fiber optic FS-V30M sensor from Keyence that is equipped with a light emitting element and receiving sensor was used. The sensor detects the position of the micro-tool by measuring the light intensity change as the tool crosses the emitted light beam. A bracket was designed and manufactured to mount the sensor onto the workpiece pallet to hold the fiber optic cable. A novel search/detection algorithm was developed and implemented in the CNC machine controller. Controlled experiments were conducted to test the performance of the tool setter. The system achieved 0.6 µm repeatability and 2 µm accuracy across different size of micro-tools. The execution of each tool setting takes about 10 seconds, which is a 80%~90% reduction from the manual tool setting.