Working in the thread rolling industry for over 60 years, CJWinter has seen its fair share of thread rolling problems of all types.
Blank diameter, material type, and rate of penetration all play major roles in the performance of your thread rolling solution. Over the years, we identified the most common thread rolling issues and developed a series of solutions to address any challenge.
Of all the thread rolling problems we see on a regular basis, the following five represent the most common issues — and our recommended solutions to address them.
1. Slivers / FlakesThe appearance of slivers or flakes within threads can indicate a number of potentially problematic causes. First, check to see if rolls are mismatched, overfilled, or of the incorrect diameter. It’s possible that rolls need to be resynchronized or the blank diameter needs to be reduced to correct the problem.
2. Drunken ThreadsThread rolls with drunken threads have an erratic pitch, creating irregularities in revolution. Unmatched rolls and misalignment may be the culprits; check to see if rolls need to be resynchronized or the slides should be better aligned.
3. Wrong Pitch or LeadTo address this problem, start by measuring as many full threads as possible using a comparator. This total measurement is then divided by the number of threads measured, resulting in the accurate pitch. In the event that the pitch has increased, resulting in a gauging problem, use modified lead (ML) rolls.
4. Mismatched Helix AngleWhen a roll comes into contact with the blank, it can result in “screw jacking;” if the attachments or roll get pulled into the collet as a result of being kept on the part for too long, it causes mismatched helix angles. To address this problem, optimize your rolling time.
5. Poor FinishWhen thread rolling does not produce the desired finish, a number of factors may be to blame. First, check to make sure that the blank diameter is the correct size to ensure that rolls are not being overfilled. If the rolls are not synchronized, adjust them to ensure smooth operation.
In some cases, material can accumulate in threads from multiple uses; if this is negatively affecting the rolls and the material cannot be removed, the rolls need to be replaced. Contamination from nearby jobs can also affect thread rolling; if chips are coming in from a nearby operation, ensure that a stream of clean oil is reaching the rolling position to keep the job clear. Finally, ensure that the material being used can be cold-worked. If not, it should be replaced with a more appropriate material.
Don’t see your thread rolling issue above? If you’re struggling with a thread rolling problem and searching for a solution, visit our CJWinter troubleshooting page for recommendations related to scuffed crests, tapered threads, split threads, and more.