ULE (an ultra-low thermal expansion glass) has great application prospects in space reflectors and large-aperture telescopes. However, conventional precision grinding restricts its efficiency and surface quality.

Ultrasonic vibration–assisted grinding (UVG) has been accepted as an effective method for processing hard and brittle materials with multiple benefits. In general, the typical UVG modes are axial ultrasonic vibration–assisted peripheral grinding (AUPG) and end grinding (AUEG). Due to the different relative motion between grinding wheel and ground surface during AUPG and AUEG, the effects on grinding mechanism and surface quality differ correspondingly. Is there any basis to choose an appropriate type of UVG?

A research team from the Xi'an Institute of Optics and Precision Mechanics (XIOPM) of the Chinese Academy of Sciences has thoroughly investigated the differences between AUPG and AUEG in grinding process. 

In this study, experiments were performed on a precision grinding machine equipped with an ultrasonic vibration air spindle system. Besides, the setup includes different kinds of grinding methods in order to explore the different effects of axial ultrasonic vibration parallel and vertical to the ground surface onto the grinding quality and efficiency.

According to the experimental results, the effect of axial ultrasonic vibration on grinding force and surface/subsurface quality during AUPG and AUEG are significantly different.

Moreover, much of this discrepancy is induced by the different comprehensive effects of axial ultrasonic vibration on workpiece contact, material properties, and material removal process.

The conclusion will be meaningful for researchers to choose the appropriate approach in applying axial ultrasonic vibration to grinding optical elements.

The results were published in The International Journal of Advanced Manufacturing Technology. 

Schematic of the OVAs experimental setup and results. (Image by XIOPM)