Study on micro grooves machining using a diamond tip with the normal force feedback control

In order to improve the machining accuracy of the conventional micro mechanical machining methods, a novel micro machining system with the constant normal force control function is established based on the constant normal force control approach of commercial Atomic Force Microscopes (AFM). The system measures the normal force signal with a force sensor and then drives a diamond tip to move up and down using a high accuracy piezo stage keeping the normal force applied by the tip within the sample a constant value during scratching grooves. Based on this system, effects of the sample materials and the target normal force on the force feedback control system are studied. The force uncontrolled and controlled scratching experiments are carried out on the PC surface. Grooves with a constant machined depth of 2.5 μm are successfully fabricated. Results show that the normal force feedback control method will remove the tilting error of the sample, the geometric error of equipments and other factors which will induce in-perpendicular errors between the tip and the sample surface. The method provided in the present study is a low cost, high accuracy mechanical machining method of micro/nano structures which have a wide application in the fields of micro optics, MEMS, etc.