Distortion is a common side effect of perforation applications. Luckily, there are ways to treat it. If oil-canning or warping is happening to you, try the following 7 techniques to flatten it out.
1. Check for proper clearance for the actual material type & thickness.
- Reduce or increase clearance as appropriate.
- Consider changing the slug retention design so the die’s clearance does not change with each sharpening.
- Positive = clearance grows
- SlugHugger® 2 = clearance grows
- Neg-Pos = clearance shrinks
- Straight Positive Taper = no change
2. Vary the hit pattern to avoid multiplying distortion when punching the pattern incrementally across the sheet.
3. Reduce the number of inserts in cluster tool.
- Every additional insert will increase the distortion.
- Remove some inserts and reprogram. Try removing every other insert, an entire row or the entire perimeter.
4. Stagger the insert heights to allow inserts to engage the sheet at separate times per hit.
- 30-60% material thickness stagger.
- Always buy full length inserts using the sharpened ones as the short ones.
5. Use a Back Bending Die (shown below) to allow the stripper to deform the sheet downward around the die relief to offset the piercing force.
Back Bending Max. A-Dim of Cluster Pattern per Die Size:
C Station = 1.200”
D Station = 2.100”
E Station = 2.700”
F Station = 3.600”
Trumpf Size 2 = 1.600”6. Apply JK Shear (below) on inserts. This helps to start the material flow down into the hole instead of outward into the sheet. The distortion in this case is transferred into the slug.
Learn more about perforation applications here.
May 01, 2018