Changing Cutting Tools Solves Three Problems in Hard-Turning Application
By switching to a new boring bar, a contract shop that specializes in precision Swiss turning and machining reduced one part’s cycle time by more than seven minutes.
While machining 2,000 bushings for a hydraulic pump used in the aerospace industry, Kyle Hawley, owner of L.A.Y. Precision Machine, recognized that the CCMT-type carbide cutting tool insert that the shop was using to bore the hole was causing three specific problems:
- Each corner only lasted 10 to 15 parts.
- The cycle time for each piece was more than eight minutes.
- The 38-microinch-Ra surface finish that the cutting tool produced was not satisfactory.
Mr. Hawley’s cutting tool supplier put him in touch with an application and sales engineer at Horn USA, who recommended the Supermini 105 tool system with an HS36-grade boring bar insert. The inserts have a carbide substrate, a high-temperature-resistant coating and an adapted cutting-edge geometry specifically designed for hard turning materials ranging to 66 HRC, eliminating the need for cubic boron nitride.
According to Mr. Hawley, the results achieved with the new cutting tool exceeded his expectations. Cycle time was reduced from 8 minutes, 5 seconds to 1 minute, 23 seconds, and each boring bar now can be used for 75 parts. In addition, surface finish Ra improved to 20 microinches. Mr. Hawley says that the boring bar can be changed out quickly, which is an additional benefit. All of this adds up to a 78 percent reduction in manufacturing cost.
Cutting holes by interpolating a face milling cutter may be a better process choice for many rough and even finish boring operations. Software improvements and better cutter designs allow expanding use of the versatile face mill for hole making.
To make the transition to hard turning, you'll need to switch from carbide to CBN inserts, but that is easier (and more economical) than you might think. It's making the jump to much higher surface speeds that might scare you off. It needn't. Here's why.
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