Inserts do it the hardfacing way

Inserts do it the hardfacing way

Cleveland Hard Facing (CHF) Inc., a full-service hardfacing and machining shop, specializes in wear, corrosion and heat-resistant overlays, graphite oxidation prevention, refractory tubes and thermowells for molten metal use.

At Cleveland Hard Facing, Greenleaf WG-300 ceramic inserts not only increase machining speeds and feeds for cutting tough welded overlays, they are the reason the shop can keep its machining work in-house.

Cleveland Hard Facing (CHF) Inc., a full-service hardfacing and machining shop, specializes in wear, corrosion and heat-resistant overlays, graphite oxidation prevention, refractory tubes and thermowells for molten metal use. Its welded overlays, which can be ceramic, nickel or cobalt superalloys, tungsten carbide and chrome carbide, fall into a hardness range of 35 to 65 Rc. To machine these tough overlays, the Cleveland-based shop relies on WG-300 cutter inserts from Greenleaf Corp. of Saegertown, Pa. The ceramic inserts not only increase machining speeds and feeds by five-fold over the shop's previously used carbide cutters, they are the reason CHF can keep its machining work in-house. "If we were still using carbide, we wouldn't be completing enough work per day to cover expenses," says Tom Mahusky, shop supervisor at CHF. "With the WG-300 cutters, we now machine parts in one day that used to take weeks."

WG-300 inserts, made of whiskerreinforced ceramic materials, offer wear and thermal-shock resistance at high surface speeds. They are especially wellsuited for machining high-nickel and other heat-resistant alloys, hardened steels, hard irons and plasma spray and weld overlays at metal-removal rates reportedly up to 10 times greater than carbide. They are available with Greenleaf's special Rough Stuff surface treatment that improves insert gripping for accuracy and speed.

CHF President Randall Wischhusen credits the Greenleaf ceramic tooling for also paving the shop's way into CNC machining. Initially it used the Greenleaf inserts for manually turning large, round overlayed parts with plenty of interrupted cuts. The drawback, according to Wischhusen, was that the machines had no guarding and the ceramic cutters ran so fast they threw chips across the shop floor. To remedy the situation, the shop purchased enclosed CNC lathes.

Since the WG-300 inserts ran even better in the CNC lathes, CHF decided to expand their use to CNC milling nonround overlayed parts, so it purchased a Haas TM2 Tool Room mill. The shop's old manual milling machines lacked the spindle speeds necessary to take full advantage of the ceramic inserts.

"We had to change our mindset with the Greenleaf ceramic inserts," explains Mahusky. "Instead of running fewer large depths-of-cut at slow speeds, as with carbide inserts, the ceramics make several shallow depths-of-cut but at faster speeds to shorten overall cycle times." These shallow cuts, typically 0.030 to 0.040-in. deep, also inflict less abuse on parts, tooling and machines. Mahusky runs spindle speeds up around 3,800 rpm, as opposed to 1,800 rpm used with carbide tooling. He initially sets feeds at 500 sfm and increases them from there — the shop's carbide tooling fed between 80 and 100 sfm.

However, CHF is not a highproduction shop cranking out large lot sizes, so a job could be finished by the time Mahusky determines optimum machining speeds and feeds. In this situation, he refers to suggested starting points that Greenleaf provides with its WG-300 inserts. www.greenleafcorporation.com

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