Drilling Technique for Optimal Performance

Joel GillardKarsten ZuendelRandy Huebner

Portland, Oregon USA

SIGN Conference 2009

Drilling Performance Factors1. Cutting edge geometry for material drilling into:

bone vs metal 2. Cutting edge retention: hardness vs. toughness

Wood Bone Metal

Cutting Edge

Drilling Performance Factors

Drilling Performance Factors

3. Drilling technique: feed & speed

Tool life & Bone temperatureAbove 47oC for over 1 minute bone necrosis

Eriksson et al 1984 Scand J Plast Reconstr Surg 18:261–268

Drill Testing Outcomes

• Feed & Speed for 3.5mm SIGN drill– Tool Life & Temp

• Practical drilling techniques

• Ideas for improving SIGN drill

Methods

•2 speeds: 400 & 1100 RPM•2 feeds: 7 lbs (3 kg) & 17 lbs (8 kg)•Synthetic bone & pig femur•3.5mm SIGN drill•Commercial general purpose 3.5mm drill

•Record time & temperature•Note wear of cutting edge

Results

Results

New 400 - 7 1100 - 7 400 - 17 1100 - 17 Bullet

•Key article comparison

Bullet

SIGN

Discussion

Highest temperature 96oC recorded for the highest speed lowest force

2900 RPM / 2 Kg

Discussion

Discussion

Discussion

RPM = 800

Bullet drill performs better than ortho equivalent drills, producing significantly less temperatures

•Higher Temp with Higher RPMs (1100 – 1400)•Lower Temp with Higher Feed Rates

Conclusion•Push on the drill (17 lbs / 8 kg): more is better than less•Faster RPM (1100) cuts quicker, but only if you push hard (17 lbs, 8 Kg), otherwise temp drill dulls•Pulse or Peck every 2 – 3 sec

•Clears debris•Reminder to push

Conclusion

•Some irrigation is better than none•Drill a small (2mm) hole first followed by 3.5mm•All drills will eventually become dull, but the can be resharpened, find a craftsman•Drills need to be properly used, cared for and maintain to have a long life