Ultrasonic-assisted micro-milling of cortical bone: An experimental study

Area of Science:

• Biomaterials Engineering
• Orthopedic Surgery
• Manufacturing Processes

Background:

• Bone machining in orthopedic surgery generates heat, risking thermal necrosis and impacting patient recovery.
• Ultrasonic-assisted micro-milling (UAM) presents a solution by decreasing cutting forces and heat production during bone processing.

Purpose of the Study:

• To investigate the influence of feed rate, rotational speed, tool diameter, depth of cut, and vibration amplitude on cutting force and temperature during UAM of cortical bone.
• To develop predictive models for optimizing UAM parameters to minimize thermal damage and preserve bone integrity.

Main Methods:

• Conducted 64 experiments on fresh bovine cortical bone specimens using varying machining parameters.
• Employed precision instruments for accurate measurement of cutting forces and temperatures.
• Utilized regression modeling and statistical analysis, including NSGA-II for multi-objective optimization.

Main Results:

• Increased rotational speed and vibration amplitude generally reduced cutting force and temperature.
• Feed rate and tool diameter exhibited complex interactive effects on machining outcomes.
• Optimized parameters were identified for both X and Y axes, achieving low predictive model errors for temperature (1.6-7.6%) and force (12.9-14.5%).

Conclusions:

• The developed predictive models can assist surgeons in anticipating bone machining conditions preoperatively.
• Optimizing UAM parameters enhances surgical safety by reducing risks associated with thermal necrosis.
• Findings support the advancement of orthopedic machining processes for improved surgical results and bone preservation.