The long-term performance of a thread rolling tool is directly related to wear of the spindles, bearings, backing plate and face plate of the rolling head. Wear of any components will present initially in pronounced taper of the finished thread.
Older style heads were equipped with needle bearings while newer style heads utilized carbide bushings. The carbide helped to maintain parallel form for longer life cycle than the needles.
Correcting taper generally requires replacing one or more of the contributing components. In a pinch, the straightness is achieved through preparation of a counter tapered part prep. This can squeeze additional life out of the tool without the time and cost of immediate repair or part replacement.
We inspect, evaluate and quote repair cost and time when tool performance becomes questionable, and the inspection is scheduled regarding production needs.