Troubleshooting Common Threading Problems that Can Occur

CJWinter has identified and solved thread rolling problems of all types over its 60+ year course.

From slivers and flakes to scuffed crests, you can find the solution to your thread rolling issue here. Click on your problem below to learn more about its cause and solution. Can’t find the information you’re looking for? Our team is more than happy to help — contact us today.

Slivers or Flakes on Threads

Problem	Solution
Rolls not in match	Resynchronize rolls
Center line of rolls not parallel with center line of work	Check slide for alignment
Loose or worn cross slide or adapter	Check slide gib and springs. Tighten adapter if used.
Overfilling rolls	Reduce blank diameter
Material not adaptable to cold-working	Change material. Check with material supplier.
Rough finish on blank	Regrind tooling
Seamy stock	Not suitable for roll threading
Feed rate too slow, causing rolls to slip on work	Increase rate of penetration
Incorrect roll diameter	Use correct rolls for job

Drunken Threads

Problem	Solution
Rolls not in match	Resynchronize rolls
Center line of rolls not parallel with center line of work	Check slide for alignment
Inaccurate rolls	Replace rolls
Work bending during rolling.	Support part during rolling operation or slow down penetration rate if possible

Off-Size Threads

Off-Size Threads	Problem	Solution
Pitch diameter and major diameter, both oversize	Oversize blanks	Reduce blank diameter
Pitch diameter oversize, major diameter correct	Oversize blanks. If finished thread is full, thread on roll is too shallow.	Use correct rolls for job
Pitch diameter oversize, major diameter undersize	Insufficient penetration on rolls. If finished thread is full, thread on roll is too shallow.	Increase roll penetration
Pitch diameter correct, major diameter oversize	Blank too large. Thread on roll deeper than necessary.	Reduce blank diameter
Pitch diameter correct size, major diameter undersize	Blank too small. If finished thread is full, thread on roll is too shallow.	Increase blank diameter. Use correct rolls for job
Pitch diameter undersize, major diameter oversize	Excessive penetration. Thread on roll deeper than necessary.	Reduce roll penetration. Use correct rolls for job.
Pitch diameter undersize, major diameter correct size	Blank too small. Thread on roll deeper than necessary.	Increase blank diameter. Use correct rolls for job.
Pitch diameter and major diameter both undersize	Blank too small	Increase blank diameter

Out-of-round Thread

Problem	Solution
Out of round blank	Shave tool not reaching center or not cleaning up rough form diameter
Center line of rolls not parallel with center line of work	Check slide for alignment
Feed rate too high	Reduce rate of penetration
Insufficient work revolutions	Reduce rate of penetration
Material not ductile enough for cold-working	Change material. Check with supplier.
Attachment not on center line of work	Reset cross slide with gauge

Tapered Threads

Tapered Threads	Problem	Solution
Pitch diameter straight. Major diameter tapered and not filled on small end	Tapered blank	Straighten blank
Pitch diameter and major diameter both tapered same way	Tapered blank	Straighten blank
Pitch diameter and major diameter tapered in opposite directions and thread not filled out on end with small major diameter	Rolls not penetrating deep enough on edge with large pitch diameter and small major diameter, or work bending during rolling	Support part during rolling. Part deflecting out of contact with center of rolls.
Thread with expanded lead	Expanded lead in rolls	Use correct rolls
Thread with expanded lead	Material extruding on short length of blank	Use longer blank and remove excess in another position
Thread with contracted lead	Contracted lead in rolls	Use correct rolls for job
Poor thread form	Work bending during rolling	Support part during rolling
Poor thread form	Rolls not in match	Resynchronize rolls
Poor thread form	Too many work revolutions	Increase rate of roll penetration
Poor thread form	Center line of rolls not parallel with center line of work	Check slide for alignment
Thread filled out in center, but not towards ends, or vice versa	Blank with varying diameter from end to end	Check blank for taper or shave tool not reaching center
Thread filled out in center, but not towards ends, or vice versa	Center line of rolls not parallel with center line of work	Check slide for alignment
Poor finish on thread	Overfilling rolls	Check blank diameter oversize.
Poor finish on thread	Rolls not synchronized.	Resynchronize thread rolls.
Poor finish on thread	Material accumulated in threads on roll.	Replace rolls if material cannot be removed.
Poor finish on thread	Material not ductile enough for cold-working.	Change material.
Poor finish on thread	Chips, from other operations, between rolls and work.	Make sure a good jet of clean oil is reaching rolling position
Poor finish on thread	Correspondingly poor finish on rolls.	Replace rolls.
Poor finish on thread	Rolls that are work or broken	Replace rolls

Split Thread-axially

Problem	Solution
Seamy stock	Change stock
Mark from shave tool or hollow mill	Regrind tooling

Crests Not Filled Out

Problem	Solution
Blank too small	Increase blank diameter
Thread on roll too deep	Replace rolls with rolls of correct depth for job. NOTE: Special truncated rolls are available from Winter.

Scuffed Crests

Problem	Solution
Attachment not retracting fast enough	Increase speed of roll retraction
Rolls and gear train building	Check gear train, remove any foreign matter
Rolling not on center line of work	Reset slide with gauge
Material accumulated in threads on rolls	Check oil jet flowing on rolling position
Insufficient wall thickness	Machine hole later in operation or use smaller drill
Improper supporting mandrel	Use proper supporting mandrel
Feed rate too high, causing too rapid penetration	Slow down penetration rate

Hollow Work, Hole Enlarged

Problem	Solution
Material extruding due to insufficient wall thickness.	Use smaller drill before rolling
Supporting mandrel too tight	Reduce mandrel diameter
Blank too large on major diameter	Reduce blank diameter
Feed rate too high causing too rapid penetration.	Slow down rate of penetration

Hollow Work, Out of Round

Problem	Solution
Material deforming due to insufficient wall thickness.	Drill later in cycle.
Feed rate too high causing too rapid penetration.	Slow down rate of penetration.
Too few work revolutions.	Slow down rate of penetration.

Hollow Work, Tapered Threads

Problem	Solution
Uneven and insufficient wall thickness.	Drill later in cycle.
Improper mandrel not giving support where needed.	Check mandrel for size with hole.
Feed rate too high causing too rapid penetration.	Slow down rate of penetration.
Taper of rolls not great enough to compensate for tendency of work to taper.	Use correct rolls for job.

If you need further assistance, please call us at 585.429.5000, or use our Contact Page to email a description of your problem. For detailed specification on particular Thread Roll Attachments, that information is available online in the Thread Roll Attachments Page. You can also download our Thread Rolling Solutions brochure to help determine correct working face and roll position.

ADDITIONAL RESOURCES

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guide to thread rolling solutions

Thread Rolling vs. Thread Cutting

Top 10 Reasons to Use CJWinter

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Troubleshooting