Tapping can increase the tensile strength of an internal thread up to twice the
tensile strength of a cut thread. Carbide taps will decrease the cycle time
required to thread by at least a factor of two.
a carbide nib form tap assembled on a steel shank to take advantage of the
speed potential while preserving overall tap strength to tangential forces. The
improved cycle times are sweetened by tap life that can be more than 10 times
the life of a steel tap.
Aluminum can be most cost effective with PCD inserts, however, insert cost is
very high. Most Aluminum is milled and turned with carbide inserts honed for
sharpness and polished to aid in chip flow. The best of both worlds is a
development by LMT Fette in Germany using a coating process defined as Plasma
CVD. The coating is applied to a honed insert and increases insert life while
maintaining the edge integrity. As an added benefit Milling speeds can be as
high as 6000sfm and turning speeds to 10,000 sfm. Speeds significantly improve
throughput and insert life can be 10 times longer than uncoated inserts. Insert
cost is comparable to uncoated polished inserts.
The mechanical characteristics of many materials can make them difficult to thread using traditional cutting technologies. Chip control and work hardening can be an obstacle to efficient machining. Cold thread forming (thread rolling) often can be used to efficiently improve machinability.
Thread rolling is especially efficient in many Nickel, Monel, Inconel, Titanium, Silicon Bronze, Copper, Brass, Copper alloys and Aluminum alloys. Typically, these materials can be threaded faster and at lower cost through rolling. The chip-less cold formed method adds strength and improves thread performance and is amendable to today’s modern production equipment. Identifying a material grade can quickly determine if rolling is a benefit both in thread cost and thread quality.
Most common thread forms UNC, UNF, UNEF, M, MF, MEF, Acme, Stub Acme and Whitworth are several thread types that are good candidates for rolling. Other forms are also capable. We can quickly identify your specific need and determine capability.
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 or all these components will manifest
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
We inspect, evaluate and quote repair cost and time when
tool performance becomes suspect and the inspection is scheduled regarding