Jektole Clearance

Jektole IllustrationThe key to increased productivity

Perforating punch to matrix (die) clearances in metal stamping dies have been universally expressed as a percentage of stock thickness, and for clarity should be expressed as percent per side.

The old "rule of thumb" called for clearance per side of 5% and is commonly known as regular clearance. It has been applied to nearly all applications in perforating ferrous materials.

Jektole, the engineered clearance, is approximately twice regular clearance per side of 10-12%. However, even greater clearances are not uncommon on some hard materials. Over 5,000 clearance tests have been performed by Dayton to prove that increasing the clearance does not lessen hole quality as has been thought by many people. Dayton clearance tests do, in fact, prove that Jektole clearance...

In production:

  • requires less press tonnage
  • reduces pressure required to strip the punch ...which in turn reduces punch wear
  • produces minimal burr
  • doubles (and often triples) piece output per grind
  • reduces total punch costs

In maintenance:

  • keeper key-holds pin in retracted position
  • eliminates the need for disassembly before grinding
  • maintains proper pin extension
  • reduces downtime from re-grinding

Jektole Clearance Testing

To assist you in determining the correct Jektole clearance for your job, Dayton offers a clearance testing service. See the Clearance Test form at the bottom of this page. Dayton will perforate your material with a range of clearances and return a sample with an analysis report.

Here's all it takes:

  1. Just provide your local Dayton distributor with two samples of your material. Samples must be 1" x 4" long with a maximum .188 thickness, burrs removed, flat, and free of holes.
  2. We test-perforate your material under simulated production conditions.
  3. Test results are analyzed and recorded on data sheets showing clearance ranges and corresponding hole characteristics.
  4. Test specimen and data sheet is returned for your examination. Allow ten working days for the completion of test and delivery time through the mail.
  5. Select the clearance based on hole size and burr height. If you desire specific hole characteristics, such as more burnish length, select the clearance to meet your requirements by examining the test strip.

Clearance Test SampleHere's Proof That Jektole Works

A typical report

The sample is 16 GA. (.0598") Cold Rolled Steel #1 Temper

All holes were perforated by Jektole punches with .1875" point diameter-radiused to .004" to simulate a wear condition. Matrix diameters were varied to produce the clearances shown.

Proven Results with Jektole Clearance

Case History #155

Die Set-Up

Perforating 29 holes, .125" dia. on .1875" centers. Material was #4 Temper, CRS, .036" thick and 4.835" wide, lightly oiled.

Press Set-Up

Press was continuously operated at 120 spm to produce approximately 57,000 hits per 8 hour shift.


Regular Clearance - 41 hours per million parts

Jektole Clearance -12.5 hours per million parts

Regular vs Jektole Clearance

Case History - Figure 1

 Punch Life
Average Hits Between Grinds Total Punch Life (# of Hits)