Once thought to be a “new way” of quenching induction heat-treated metals, polymer quenchants are establishing some impressive credentials at heat treaters around the world. The metallurgical performance of these solutions, coupled with their distinct environmental advantages over other means of quenching, has made polymers the quenchant of choice at an increasing number of companies.

Thermet, Inc. of Waukesha, Wisconsin is one such company.

  Since the firm was founded in 1977 by President Jim Murphy, Thermet has been a local leader in induction heat treating, building its reputation as a high-quality, service-oriented company. Thermet boasts five new induction scanners with capacity to 72” vertical. Each unit is computerized for uniform performance and consistency, batch to batch. In addition, a variety of high and low frequency power supplies can produce case depths as shallow as .010” and as deep as .600”. Coupled with the servo-driven vertical scanners and dual pop-up workstations, Thermet typically hardens shafts and pins from 1” to 72” in length; gears, pinions and sprockets to 25” diameter; bearings, ball screws, bolts, guide shafts, piston sleeves and other products up to 750 lbs. The quality heat treating is supported by the company’s state-of-the-art lab, which includes sample preparation, a metallograph for microstructure analysis and photo micrographs, microprocessor-based micro- and macro-hardness testers, as well as magnetic particle inspection.

  Thermet also maintains a complete inductor manufacturing and repair operation in-house, plus it boasts a large and diverse inventory of coils and fixtures to match virtually any incoming project.

  The company houses a total of 12 machines and processes approximately 500,000 piece parts annually, typically in small lots. Thermet’s customers include various contract machine shops, as well as some of the OEM’s in the equipment, electric tools, engine and pump industries who utilize this commercial heat treater as a merchant supplier or to augment their own heat treating.A variety of steel alloys are processed, including 1045, 1050, 1141, 1144 stressproof, 4140 and 4150.

  As Vice President—Operations Paul Mikna observes, “Our capacity and our technical assistance combine to give our customers a powerful resource who’s nearby and very committed to service. We support our service at all times through immediate response to customer needs. When a customer has a problem or a change to a material spec, they know we can employ our lab technology to quickly solve that problem or develop an alternative processing protocol to achieve the desired results.”

  Now entering its 25th year in business, Thermet has exclusively used UCON® A, a non-flammable, aqueous solution of liquid organic polymer and corrosion inhibitor, originally patented by Tenaxol, Inc. of Milwaukee and manufactured by Dow Chemical Company (formerly as Union Carbide Corpora-tion). The organic polymer is water-soluble and produces a clear homogenous solution at room temperature. At high temperatures, the polymer separates from the water as an insoluble phase. For example, when hot metal is quenched in a diluted solution, the film of liquid polymer is deposited on the surface of the metal. The rate of metal cooling is determined largely by the cooling rate of the polymer film, as well as by quenchant concen-tration, agitation and solution temperature. By the predetermined adjustment of these parameters, Thermet is able to use their UCON® A quenchant for a wide range of induction heat treating processes, performed on an equally broad spectrum of steel alloys.

Shafts and pins up to 72" in length are induction-heated at Thermet, then quenched in UCON® Type A, a non-flammable aqueous solution of liquid organic polymer and corrosion inhibitor.

Twin steel guide shafts were induction-heated, then quenched in a 24" vertical scanner, built by Thermet, where the UCON® polymer quenchant is used.

  UCON® A permits a fast quench rate and uses an inorganic nitrite salt as the corrosion inhibitor. Typically, re-sidual stress and cracking tendencies are reduced by the use of this quenchant, in comparison to oil, brine, salts or other media.

  On one job at Thermet, a 6”x 4” dia. x 1û4” wall piston sleeve of 1050 material, the quenching was done in a 3% concentrate of UCON® A at 85æF in less than one minute, with consistently good quality levels.

  As Thermet’s Paul Mikna comments, “We get very consistent and predictable results with UCON® A polymers. By using a quenchant of which we know the behavior, we’re better able to streamline our machine set-ups for optimum workflow through the shop.” Thermet uses 3-4 drums (55 gal. ea.) of UCON® A each month.

TA 6" x 4" diam. x 1/4 wall thick piston sleeve of 1050 material, being spray-quenched at 85 degrees F with a 3% concentrate of UCON® polymer quenchant..

  Thermet President Jim Murphy recounted his first experience with polymer quenchants. “I was at Evinrude back in 1966, when Ross Blackwood (founder and CEO of Tenaxol) introduced me to the concept, which he’d pioneered just a few years earlier. We began to use it at Evinrude, then I continued to use it at Treat All Metals in 1975. Larry Jarvis (now President of Tenaxol) worked there, back in those days, and our relationship with Tenaxol prospered to our mutual benefit. The metallurgical support we received was and is as valuable today, as back then. When I founded Thermet in 1977, there was no question about the quenchant technology we would use. UCON® A has been doing the job for us for 25 years now. We’ve investigated other quenchants, even tried other UCON® formulae, but UCON® A remains our quenchant of choice.”

Paul Mikna mused, “We have one small oil quench tank, but in my nine years here, I must say it hasn’t gotten much use. Polymer quenching, whether immersion or a spray system, is absolutely the way to go.”

For more information on this story, please contact:
 THERMET, INC., 203 Travis Lane, Waukesha, WI 53189. Phone: (262) 544-9800; Fax: (262) 544-5959.
Web: www.thermet.com. Paul Mikna, Vice President—Operations or
TENAXOL, INC., 5801 W. National Ave., Milwaukee, WI 53214. Phone: (414) 476-1400; Fax: (414) 476-4297. Web: www.tenaxol.com; Email: info@ tenaxol.com. Larry Jarvis, President.