Effect of kinematic parameters considering workpiece rotation on surface quality in YAG double-sided planetary lapping with the trajectory method

• Published in: International journal of advanced manufacturing technology 2022-12, Vol.123 (7-8), p.2679-2690
• Main Authors: Yang, Lei, Guo, Xiaoguang, Kang, Renke, Zhu, Xianglong, Jia, Yufan
• Format: Article
• Language: English
• Subjects: CAE) and Design; Coefficient of variation; Computer-Aided Engineering (CAD; Confined spaces; Engineering; Flatness; Industrial and Production Engineering; Kinematics; Lapping (finishing); Measurement methods; Mechanical Engineering; Media Management; Nonuniformity; Optimization; Original Article; Planetary rotation; Rapid prototyping; Simulation; Surface properties; Surface roughness; Trajectory analysis; Valleys; Workpieces
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-022-10288-y

Because of the complexity of the measurement in a confined space the effect of workpiece rotational speed on surface quality, such as the uniformity of surface roughness ( R a ) and peak-to-valley (PV) error of flatness, has not been revealed during the double-sided planetary lapping process. To resolve this concern, a method to measure the workpiece rotational speed is proposed, and the mathematical model for calculating the grit trajectory left on the workpiece in double-sided lapping considering the workpiece rotational speed is established. A variation coefficient for nonuniformity of the track point distribution ( NUTPD ) is introduced to evaluate the trajectory uniformity. Subsequently, the trajectory map of multiple grits and the value of NUTPD were simulated at different variations, which include the rotational speed ratio γ of the pad to the sun gear, and the rotational speed ratio η of the workpiece to the sun gear. The simulation result shows that the uniformity of the trajectory of the grits left on the workpiece surface is significantly affected by the rotational speed ratios γ and η. Furthermore, to verify the reliability of the simulation, corresponding processing tests were conducted by employing a double-sided planetary lapping machine with YAG wafers. The results show that the uniformity of the surface roughness and the peak-to-valley error of flatness can be reflected in the values of NUTPD . By selecting optimal rotational speed ratios η , better flatness and surface roughness of YAG can be achieved for the lower nonuniformity of trajectory distribution. The above analysis confirms that the method of measuring the rotational speed of the workpiece and trajectory analysis can significantly contribute to optimizing the rotational speed ratio γ . In addition, the above method can provide guidance for the optimization of rotational speed ratio η to obtain more uniform roughness and better flatness of the workpiece surface.