Studies on the critical cutting force in rotary ultrasonic drilling of brittle materials

Significance 

Unique chemical and mechanical properties of hard and brittle materials make them viable for various industrial applications. Due to their hardness and toughness properties, brittle and hard materials, however, are most difficult to machine materials through conventional processes. Although various unconventional processes can be used for machining such materials, rotary ultrasonic drilling with utilization of tool’s ultrasonic vibration has been proved as a superior method for machining such materials. Ultrasonic vibration assisted machining is a method that can be applied in different fields that deals with processes involving hard to cut materials.

The use of rotary ultrasonic drilling technique has been effectively applied in hole-manufacturing of hard and brittle materials. It is beneficial for reducing the cutting force required for the process, preventing subsurface damage, increasing tool life and enhancing the quality of the drilled hole. The tools used in the rotary ultrasonic drilling can also be used for other applications apart from drilling such as face milling.

However, due to the availability of different materials with varying degrees of hardness and brittleness, there is need to experimentally and theoretically investigate the validity and effectiveness of rotary ultrasonic machine tools. This will enable proper design and manufacture of such machine tools to favor various areas of applications.

Researchers led by Professor Pingfa Feng from Tsinghua University in China, and in collaboration with their colleague Professor Ping Guo at The Chinese University of Hong Kong conducted a study on machining hard and brittle materials through the rotary ultrasonic drilling technique. Their main aim was developing a model for critical cutting force that guarantees the effectiveness of rotary ultrasonic machine tools. Their work is published in the journal, International Journal of Mechanical Sciences.

From the conducted experiments, the authors observed that an unstable decrease in the ultrasonic amplitude resulted in a corresponding unexpected increase in the cutting force. This leaded to the severe suppression of the processing superiority of rotary ultrasonic machining in terms of cutting force reduction. According to the authors, cutting forces was the chief contributor to the instability of the ultrasonic amplitude. A critical value of cutting force is found. When the cutting force exceeded a critical value, it would increase abruptly. This was observed in both carbon composite and quartz glass materials.

From the theoretical and experimental results, the authors concluded that critical cutting force was an inherent property of rotary ultrasonic machine tools depending on the corresponding excitation level, being independent of the processing conditions. The authors proposed critical cutting force as an ideal index that should be taken in consideration during the design and manufacturing of rotary ultrasonic machine tools.

critical cutting force in the rotary ultrasonic drilling of brittle materials and composites. Advances in Engineering

About the author

Prof. Pingfa Feng received his B.S. degree (1987) and MSc. degree (1989) in Mechanical Engineering from Tsinghua University and his Ph.D. degree in Mechanical Engineering from Technical University of Berlin in 2003. Now he is a professor in the Department of Mechanical Engineering at Tsinghua University.

His research interests include ultrasonic vibration assisted machining, intelligent manufacturing, high speed cutting, performance analysis and optimization of manufacturing equipment, CNC in situ measurement, etc.

About the author

Prof. Jianfu Zhang received his B.S. degree (1999) and MSc. degree (2004) in Mechanical design and manufacturing from Shenyang Ligong University, and his Ph.D. degree (2009) in Mechanical Engineering from Tsinghua University. Now he is an associate professor in the Department of Mechanical Engineering at Tsinghua University.

Dr. Zhang’s research interests include the ultrasonic vibration assisted machining, intelligent manufacturing system and digital design and manufacturing technology.

About the author

Dr. Jianjian Wang is a Postdoctoral Research Fellow in the Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China. He got his B.S. degree in Mechanical Engineering from Shandong University (2011) in Ji’nan and a Ph.d. degree in Mechanical Engineering from Tsinghua University (2017) in Beijing.

Dr. Wang’s research interests center on the paradigm of unconventional machining, including rotary ultrasonic machining of hard and brittle materials, elliptical vibration texturing, processing of bulk metallic glass, performance analysis and optimization of power chuck, etc.

About the author

Prof. Ping Guo received his B.S. degree in Automotive Engineering from Tsinghua University in 2009 and his Ph.D. degree in Mechanical Engineering from Northwestern University in 2014. Immediately after his graduation, he joined the Department of Mechanical and Automation Engineering at the Chinese University of Hong Kong as an assistant professor. Dr. Guo’s research interest center on the paradigm of micro/meso-scale manufacturing, including surface texturing, process micro-mechanics, miniature machine tools, micro-additive manufacturing, etc.

He serves as an associate editor for SME Journal of Manufacturing Processes. He is the recipient of Hong Kong Research Grants Council Early Career Award (2016), and the Best Paper Awards of International Conference on Nano Manufacturing (2016) and International Conference on Micro Manufacturing (2013).

Reference

Wang, J., Zhang, J., Feng, P., & Guo, P. (2018). Experimental and theoretical investigation on critical cutting force in rotary ultrasonic drilling of brittle materials and composites. International Journal of Mechanical Sciences, 135, 555-564.

 

Go To International Journal of Mechanical Sciences

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