Angle head key to keyway machining

END USER: PMC-Colinet, (800) 451-1306, www.pmc-colinet.com.
CHALLENGE: Boost productivity when machining keyways into a Nitralloy steel cutting tool head.
SOLUTION: Switch the work to a vertical machining center and obtain a custom 90° angle head.
SOLUTION PROVIDER: Heimatec Inc., (847) 749-0633, www.heimatecinc.com.

Founded in 1912, PMC-Colinet, Wickliffe, Ohio, is a builder of machines for the oil-country-tubular-goods sector. The company’s customers include integrated steel mills that sell finished pipe and couplings to the oil and gas industries. The mills use the machines to thread products for down-hole drilling. PMC-Colinet also supplies cutting tools, consumable tooling and aftermarket parts and provides field service.

One particularly challenging job requires cutting keyways into a large section on a cutting tool head made of Nitralloy steel. For many years, PMC-Colinet used a shaping machine to produce the keyways in the bores of die heads. Typically, the bores range from 6 ” (152.4mm) to 13 ” (330.2mm) in diameter and more than 12 ” (304.8mm) in length. The keyway tolerances are tight, with location at ±0.0005 ” (0.013mm), width at ±0.001 ” (0.025mm) and depth at ±0.0025 ” (0.064mm).

One style of cut is a three-step keyway that does not run all the way through the bore, stopping instead at a window milled from the part’s OD. This situation posed two options. One required PMC to rough the keyway on the shaper, then outsource the part for finishing with a sinker EDM because PMC doesn’t have that type of machine. This process consumed 50 hours on the shaper, plus about a week for the EDM work.

Another option was to do the job entirely on the shaping machine. Roughing the keyway required about 61 hours. Finishing consumed another 145 hours. The roughing and finishing times included 10 to 12 hours for setup.

Courtesy of Heimatec

Heimatec designed this special 16 “-long, 90° angle head for cutting the keyway in a cutting tool head used in the oil field industry.

Milling Foreman Rick Kokish said PMC used both options, depending on which method could get the job done the quickest. “We had one vendor we used who had a large enough EDM to handle our larger heads. We were pretty much at their mercy as to when they could get a head on the machine based on their work load.”

The team at PMC decided to explore methods to increase productivity by producing the part on its Monarch 175B vertical machining center. However, doing so required a 90° angle head to cut a keyway with sharp corners in a bore as small as 6.00 ” in diameter that is parallel to the keyway, so the team conducted an exhaustive Internet search. After more than 30 hours of weeding out unsuitable products, two vendors remained. “First, we eliminated heads by size,” Kokish said. “If the angle head could only do one or two different sizes, it would not be a great fit for us.”

He added that price was also a factor—but not from a budgetary standpoint. “If the cost was very low, we felt we would probably suffer on quality.”