Hardened layer issues: Causes and Fixes
October 2, 2026 · Exactalloy Technical Team
Hardened layer issues is almost never caused by a single factor. Work through the causes in order of probability before changing tooling.
Quick answer: Check in this order: rigidity and run-out first, then coolant and chip evacuation, then cutting parameters, and only then the tool grade or coating.
Ranked causes
Run-out and holder condition, machine and fixture rigidity, cutting parameters, coolant delivery, then tool geometry and grade.
Checks to run
Measure edge run-out, inspect the chip, check the coolant pressure and aim, and confirm the programmed feed matches the intended chip load.
Parameter fixes
Change one variable at a time and re-measure; record what worked so it becomes a standard for the next job.
When to change tooling
Only after the machine, holder and parameters have been eliminated.
Specifications at a glance
| Symptom | First check | Likely fix |
|---|---|---|
| Recurring problem | Run-out at the cutting edge | Re-seat or replace holder |
| Worsens with speed | Rigidity | Reduce overhang, shorten tool |
| Localised failure | Chip evacuation | Improve coolant or reduce ap |
| Random failure | Material batch | Verify hardness and grade |
Frequently asked questions
Should I reduce speed or feed first?
Reduce speed and hold or raise feed; reducing feed causes rubbing and makes most of these problems worse.
How many variables should I change at once?
One. Changing two makes the result uninterpretable.
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