Like a dream come true

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END USER: Bear Manufacturing LLC, (832) 272-1245. CHALLENGE: Eliminate insert corner failure when ID turning Inconel 725 parts. SOLUTION: An advanced carbide insert grade and geometry. SOLUTION PROVIDER: Sandvik Coromant Co., (800) SANDVIK, www.sandvik.coromant.com/us

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Machined metal parts for the offshore oil industry must be made of materials that withstand the high pressures they’re subjected to in the subsea environment. “They may have to go down a mile of water before they even hit the ground and start drilling,” said Mark Bear, owner of Bear Manufacturing LLC. The Houston job shop has specialized in the offshore, down-hole oilfield industry for the 7 years it has been in business.

Such a demanding environment often requires parts made of difficult-to-machine, heat-resistant, high-nickel superalloys, such as Inconel 625, 718 and 725. One such part was an Inconel 725 lower bonnet, and Bear Manufacturing was tasked with producing about 1,000 of them.

According to Bear, the biggest challenge was ID turning, in part because the workpiece tends to generate long, stringy chips that promote tool failure as they collect in the hole. “You’re flirting with disaster when Inconel starts stringing up,” he said.

ID turning involved roughing on a Mori Seiki SL-4 CNC lathe and finishing on the lower-horsepower SL-2 lathe. The 2¼ “-deep ID starts at 17⁄8 ” and finishes at 11⁄8 ” after roughing. Unfortunately, rough ID turning the Inconel 725 pushed the corner off of the CNMG carbide inserts Bear was applying. “It would crush them,” he said.

Courtesy of Sandvik Coromant