Conicity Lab Test 3
Drilling Epoxy/Carbon Fiber Composite
Test Information
• Company: sp3, Inc.
• Test Site: Mountain View, CA
• Date: April 2003
Test Design
• Objective: Evaluate the effect of edge geometry on hole size
• Tool Styles: .250" Jobber Drill
• Edge Preparations:
• Up-sharp drill
• 0.0005" variable EMG™ hone
• Test Part: Epoxy Resin/Carbon Fiber composite sheet
Figure 1.
Hole Size as a Function of the Number of Holes Drilled
for a Standard Jobber Drill
Figure 2.
Hole Size as a Function of the Number of Holes Drilled
for a Jobber Drill with EMG
Test Summary
• Up-sharp drill hole size was extremely erratic due to rapid tool wear resulting in increased "tool rubbing" causing excessive heat generation and material "swelling"
• The Conicity EMG drill produced holes that consistently decreased in size with the number of holes drilled. This is indicative of a tool which is truly cutting and not rubbing.