An experimental study on the vibration response of a robotic machining system

Abstract

Robotic machining is one of the most versatile manufacturing technologies around, whose emergence helped reduce the machining cost of complex parts. However, its application is sometimes limited due to the low rigidity of the robot, whose stiffness leads to high vibration levels, which limit the quality and the precision of machined parts. In this study, the vibration response of a robotic machining system was investigated. To that end, a new method based on the variation of spindle speed was introduced for finishing the aluminum aerospace grade alloy (7075-T6) blocks. With the proposed method, the vibrations and the cutting force signal were collected and analyzed to find a reliable dynamic stability criterion, and the proposed criterion was validated using the machined surface roughness obtained. It was found that the directional root mean square (RMSdirectional) of the vibration signal is a good indicator for defining the degree of stability of the machining process. Moreover, it was observed that the spindle speed with the lowest RMSdirectional is the one that has the highest probability of generating the best surface finish. It was further demonstrated that the sensors are more efficient when positioned on the spindle. The proposed method is rapid and makes it possible to avoid trial and error tests during robot programming.