Effect of feed rate and drill speed on temperatures in equine cortical bone.

The study investigates how the speed of a drill and the rate at which it’s used affect the amount of heat produced in horse bone tissue, and thereby the risk of damage from heat. The results suggest that maintaining low drill speeds and applying enough pressure to quickly penetrate the bone can help reduce the risk of thermal damage.

Research Methodology

• The researchers collected 10 metacarpal bones from five 2-year-old draft-type horses for this experiment.
• They used a precisely controlled machine shop mill for drilling on these bones, using 6 different combinations of feed rate and drill speed.
• The feed rate variations used for the drill were 1, 2, and 3 mm advance/s, and the variations in drill speed were 317 and 1,242 rpm.
• The application of these drill speed and feed rate combinations allowed the researchers to note the heat produced at various stages.
• Temperature readings were recorded at three different distances from the drill: 1mm, 1.5mm, and 2mm – using thermocouples.

Findings and Conclusions

• The study found that increasing the feed rate significantly reduced the peak temperature. This means moving the drill faster through the bone material resulted in lower heat build-up.
• Increasing the speed of the drill, on the other hand, significantly increased the peak temperature, suggesting that faster rotation of the drill bit caused more heat generation.
• The research also found that the thickness of the cortical bone increased the overall temperature. This may be due to the increased resistance offered by thicker material causing more friction and heat.
• Interestingly, increasing the distance from the drilling spot significantly reduced peak temperatures. This suggests that the heat produced during drilling drops rapidly as we move away from the drill hole.
• Based on these results, the researchers recommended using low drill speeds, while applying enough force to rapidly advance the drill through the bone. This combination was found to create favourable conditions that minimize the risk of thermal damage.
• The research also suggested that in a practical setting, if a high-speed drill is used on horse bone, it could potentially produce enough heat to cause significant thermal necrosis or tissue death due to heat, which is a critical insight for veterinary surgical procedures.