Optodynamic study of multiple pulses micro drilling.

Area of Science:

• Materials Science
• Laser Physics
• Manufacturing Engineering

Background:

• Pulsed laser micro-drilling is a key manufacturing process.
• Understanding the underlying physical phenomena is crucial for process optimization.
• Optodynamic effects, including thermal responses and shock wave generation, play a significant role.

Purpose of the Study:

• To analyze the optodynamic phenomenon during pulsed laser micro-drilling of metals.
• To investigate the relationship between laser pulses, thermal effects, and shock wave generation.
• To develop a theoretical model for predicting ablation rate and hole depth.

Main Methods:

• Utilized a non-contact optical method (arm compensated Michelson interferometer) to detect ultrasonic shock waves.
• Monitored micro-drilling parameters like ablation rate and efficiency via optodynamic signal analysis.
• Developed a theoretical model based on energy balance, considering heat transfer from the laser beam to the material.

Main Results:

• Observed decreasing ablation rates leading to finite hole depths during the micro-drilling process.
• Experimental results showed good agreement with the theoretical model's predictions.
• The model successfully explained the finite hole depth as a result of increased surface area for heat dissipation.

Conclusions:

• Optodynamic phenomena, specifically thermal effects and induced ultrasonic shock waves, are critical in pulsed laser micro-drilling.
• The proposed energy balance model accurately predicts the decreasing ablation rate and finite hole depth.
• This study provides valuable insights for optimizing laser micro-drilling processes in various metals.