Record the failure before changing the tool
PCB drill bit breakage can have several contributing factors. Record when the failure happens, the tool specification, board stack and machine conditions before deciding that the geometry or cutting parameters are the cause.
Locate the stage of the failure
Note whether the drill breaks at entry, during the drilling cycle, on withdrawal or after a repeatable amount of use. Keep representative failed tools, affected workpieces and photographs. A breakage photograph alone does not establish the root cause.
| Check | Record or inspect |
|---|---|
| Tool and holder | Tool dimensions, seating, collet cleanliness and visible wear. |
| Spindle | Measured runout, maintenance history and any relevant machine alarms. |
| Board stack | Material, thickness, stack movement, clamping and support. |
| Drilling cycle | Programmed settings, actual readings if available, entry and withdrawal stages. |
| Chip evacuation | Observed debris, flute condition and extraction arrangement. |
Check mechanical conditions
Inspect the holder, tool seating and board support in accordance with the machine procedures. Do not compensate for a known setup defect by changing tool family alone. Compare the actual tool length and working clearance against the intended operation.
Review the process with a controlled trial
Use settings approved for the equipment, material and tool. Where practical, change one factor at a time and keep a written record. The purpose is to distinguish a repeatable improvement from a change caused by a different board stack or inspection method.
Separate tool selection from failure diagnosis
If the complete tool specification is unclear, first check diameter, flute, shank and overall length. Compare standard and undercut drill geometries using the actual drawings rather than relying only on a family name.
What to send with a breakage enquiry
- Tool reference, dimensions and approximate use before failure.
- Board material, thickness and stack arrangement.
- Machine model and operating conditions.
- Failure stage and representative photographs.
- Recent changes to tools, materials, setup or parameters.
Common questions
Does a broken drill prove the tool was defective?
No. Tool condition, setup, material and operating conditions all need inspection. Retain the evidence and use a qualified process review before assigning a cause.
Should I simply reduce feed or change spindle speed?
A parameter change should follow the machine and tooling guidance for the application. This checklist does not supply a universal speed or feed recommendation.
For an initial selection discussion, send the application details. This checklist supports information gathering; it is not a remote diagnosis.
Discuss your application
Share the board material, tool dimensions and the issue you are seeing.
Prepare an enquiry ↗