ISO 9001:2015 Certified Manufacturing
Pilot Hole Design for Metric Thread Formers
Optimize Material Displacement for High-Strength Internal Threads
99.9%
Accuracy Rate
24/7
Global Ops
200+
Containers/Yr
Calculators & Converters
Maximizing Thread Performance through Displacement
Thread forming differs from traditional tapping because it displaces material rather than cutting it away. This process creates a stronger internal thread by improving the grain flow of the metal. Because no chips are produced, the success of the joint depends entirely on the precision of the pilot hole.
If the pilot hole is too small, the torque required will spike, likely breaking the forming tool. If it is too large, the crest of the thread will not form completely, resulting in a weak joint with insufficient engagement. Calculating the exact hole diameter based on your material’s ductility is the only way to ensure a reliable assembly.
The 65-75% Rule
For most industrial applications using thread formers, a 65% to 75% thread height provides the best balance between pull-out strength and tool life.
Interactive Pilot Hole Calculator
Select your nominal metric size and desired thread percentage to determine the correct drill size for your application. Use these values to prevent tool breakage and optimize joint strength.
Pilot Hole Design (Metric Formers)
Calculate recommended starting hole diameters for cold-forming (roll) taps.
Recommended Pilot Hole
Millimeters
65% Thread Hole
5.60
75% Thread Hole
5.55
85% Thread Hole
5.50
Cutting Drill Ref
5.00
Pilot Hole (Scientific - Meters)
0.00e+0
*Values based on roll tap (forming) standards. Unlike cutting taps, forming taps displace material, requiring a larger starting hole.
Formula: $D = d - (0.45 \times P)$ for standard 75% thread.
Impacts of Pilot Hole Precision
Troubleshooting Your Tapping Process?
Our engineering team can evaluate your material type and application to recommend the ideal pilot hole specs for your production line.