Broaching Machine Troubleshooting: Causes & Fixes

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Problems on this page:

Broached form out of tolerance Rough or torn surface Broach breaking Burrs at the exit Hydraulic drive slow or uneven Puller not gripping the broach Broach life short Long broach changeovers

Broached form out of tolerance

Hits OEE: Quality

Symptoms: The keyway, spline or form measures outside tolerance.

Broach teeth worn

Check the broach against its sharpening record and resharpen it.

Part not located square to the broach

Check the fixture face and locating.

Broach guide worn

Check the guide bushing and pilot.

Wrong broach for the part

Check the broach number against the routing.

Prevention: Form checked with a gauge on the first part and at set intervals.

Rough or torn surface

Hits OEE: Quality

Symptoms: The broached surface is rough, torn or has built-up edge marks.

Cutting oil wrong or not reaching the teeth

Check the oil type and the flow to the cut.

Broach dull

Resharpen the broach.

Cutting speed wrong for the material

Check speed against the tool data.

Chips packing in the gullets

Clean the broach between strokes and check the chip brush.

Prevention: Surface checked on samples.

Broach breaking

Hits OEE: Availability

Symptoms: The broach snaps during the stroke.

Part hardness too high

Check incoming hardness.

Too much stock left from the previous step

Check the pre-broach bore size.

Chips packed in the gullets

Keep the chip brush and flushing working.

Misalignment between puller and part

Check the alignment of the pull head and fixture.

Prevention: Broach breakages recorded by cause.

Burrs at the exit

Hits OEE: Quality

Symptoms: Heavy burrs form where the broach leaves the part and need extra work to remove.

Broach teeth dull

Resharpen the broach; dull teeth push metal out instead of cutting it.

Exit face not supported

Support the exit face of the part in the fixture so it does not flex as the last teeth pass.

No deburring step in the routing

Add a deburring operation after broaching where the drawing requires a clean edge.

Soft, gummy material smearing

Check the cutting oil and the speed for that material with the tool supplier.

Prevention: Exit edges checked on samples from each batch.

Hydraulic drive slow or uneven

Hits OEE: Performance

Symptoms: The broaching stroke slows down, jerks or stalls part way through the cut.

Hydraulic oil low or running hot

Check the oil level and the oil cooler, and look for leaks.

Hydraulic filter blocked

Change the filter and check its indicator.

Pump worn and losing output

Measure the pump output and pressure under load.

Directional or flow valve sticking

Clean or service the valve, and check the oil cleanliness that caused it.

Prevention: Hydraulic oil condition and stroke speed checked on the maintenance plan.

Puller not gripping the broach

Hits OEE: Availability

Symptoms: The pull head slips on the broach shank or will not latch, so the cycle stops.

Puller jaws worn

Replace the worn jaws as a set.

Broach shank or pull end damaged

Inspect the shank for burrs and wear, and repair or replace the broach.

Latch mechanism packed with chips

Clean the pull head and keep chips away from it.

Air or hydraulic pressure to the head low

Check the supply pressure to the pull head.

Prevention: Pull head and jaws inspected weekly.

Broach life short

Hits OEE: Availability

Symptoms: Broaches need sharpening after fewer parts than they used to run.

Wrong or worn out cutting oil

Use the specified cutting oil and check its condition.

Parts harder than the drawing allows

Check the hardness of incoming parts.

Poor sharpening restoring the wrong geometry

Check the sharpened broach against its drawing before use.

Cutting speed too high for the material

Reduce the speed to the tool data for that material.

Prevention: Parts per sharpening recorded for each broach.

Long broach changeovers

Hits OEE: Performance

Symptoms: Changing to a different broach and fixture takes long and holds up the next job.

Next broach not staged at the machine

Bring the next broach and fixture to the machine before the current job ends.

Fixture change needs many bolts and adjustments

Use quick-change fixtures with locating features.

No written changeover sequence

Write a standard sequence and train each setter on it.

Heavy broaches handled without a lifting aid

Provide a lifting aid so the change is quicker and safer.

Prevention: Changeover time recorded per job.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: gear hobbing machine · lathe · CNC machine · hydraulic system · deburring machine

Stop the same fault coming back

Recurring broaching machine stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover