When an edge chips, the first instinct is to blame the steel. Usually the steel is fine. A chipped blade is nearly always a mismatch between the edge and the way it is being used — and because a chip and a worn edge look nothing alike under a light, you can usually work out which one you have before you order a replacement.

Wear, chip, crack — three different failures

1. The edge angle is too sharp for the material

A thin, keen edge cuts beautifully and has very little metal behind it. Put that edge into a stack with a nose wire, a thick weld seam or any interruption in the web, and the edge folds or chips at the first hard spot. Opening the bevel a few degrees trades a little sharpness for a great deal more edge strength. If your blades fail by chipping rather than by dulling, this is the first thing to question.

2. The blade is harder than the job needs

Higher hardness buys wear resistance and costs toughness. Taking a blade up the hardness range to make it last longer can push it past the point where it survives shock loading, and then it stops wearing out and starts breaking. Hardness should be chosen for the material and the machine, not for the spec sheet. The material guide compares the trade-off across HSS, D2 / SKD11, stainless and solid carbide.

3. Runout, misalignment or a badly seated blade

A blade that is not sitting flat, or that has visible runout, is being loaded unevenly on every revolution. The symptom is an edge that chips in one place while the rest is barely used — a strong clue that the problem is the setup, not the steel. Check seating, clamping and runout before ordering a replacement.

4. Wrong clearance between the blades

Paired blades need clearance matched to the material thickness. Too little and the edge rubs, heats and work-hardens until it fails. Too much and the material folds instead of shearing, which loads the edge in the direction it is weakest. On a mask machine this applies to the paired scissors blades and the cutter just as much as to a slitting pair.

5. A jam or a foreign object

The sudden failure has an obvious signature: one deep chip, everything else clean. A fold of material, a wire, a clip or a weld seam that should not have been there transmits a shock the edge cannot absorb. There is no geometry that survives this, so treat it as an operating event rather than a blade fault.

6. Heat

Continuous high-speed cutting with no dwell time raises edge temperature. Heat softens the very hardness you paid for, and the edge then fails by rapid wear or deformation. Better clearance, a cleaner cut and not running the station dry all reduce it.

What we do when a chipped blade arrives

Send the failed blade and tell us what happened — how long it ran, what it was cutting, and whether the failure was sudden. We measure the geometry, check where the damage sits and tell you honestly whether it was a material problem or a setup problem. If it was setup, a replacement ground to the same drawing will fail the same way, and we would rather say so than sell you the blade twice.

Related: how to measure a cutting blade if you have no drawing, and how often to change mask machine blades if the failure is gradual rather than sudden.