Bandsaw blade life increased 15-fold

Manufacturing Engineering, Sep 1998

Slicing blanks from centrifugal-- cast gray iron and ductile-iron tubing dulls even the best bandsaw blades. That's what a major automotive parts manufacturer found when it sought to improve production rates.

A critical bottleneck existed at the cut-off operation. Depending upon the part produced, the sawing operation cuts either centrifugal-cast gray or ductile-iron tube stock. Both metals are difficult to cut, and their abrasiveness slowed production and shortened the life of conventional bandsaw blades. Blade wear quickly compromised the quality of cut pieces.

Cutting problems didn't end there, however. Because the stock is tubular, sawblade teeth experienced twice the interrupted cutting forces as when cutting a solid. That interrupted cut caused both mechanical and thermal shock as each tooth entered the cut, crossed the void inside the tube, re-entered the cut, and exited. Under such conditions, conventional bimetal and carbidetipped blades dulled quickly and caused wavy cuts. In an attempt to deal with the problems, the company tried nearly every blade on the market.

"I was almost at the point where I considered outsourcing the cut-off operation," recalls a production engineer. The saw-- maker, HEM Inc. (Pryor, OK), suggested it could help him, pointing out past successes with a carbide-tipped blade. Fitted with a Series 3869 Carbide Triple Set shock-resistant blade made by Sandvik (Fair Lawn, NJ), a HEM Model H105A corrected the production problems. The company reduced its cycle time from three minutes, 45 seconds to less than a minute-and-a-half. Parts-per-- blade counts climbed to 1500.

"Despite the operating conditions, we never break blade teeth, and consistently get straight, smooth, surface cuts," the engineer says. "Nor have we experienced metal breakout. Our scrap rate for this operation has dropped to nil." Compared with earlier blades cutting abrasive tube stock, the 15', 8" (4.8 m)long, Series 3869 Triple Set blade from Sandvik Saws and Tools Co. increased output per blade 15fold. It also cut individual part cycle time by more than 50%.

Key to the success on such abrasive materials is the Sandvik Triple Set configuration-one tooth set left, one tooth unset, and one tooth set right. Combined with carbide blade tips, this geometry helps account for the improved performance. Sandvik's Triple Set design helps clear chips while leaving a clean kerf about 0.0125" (0.32 mm) wide. Hard, abrasion-resistant carbide gives the blade its long life, and special bonding techniques keep the carbide attached to the blade. The blade tooth gullet helps evacuate chips quickly, and avoids chip build-up in the center of the tube, where debris could damage the surface. For more information on Sandvik Series 3869 Carbide Triple Set blades

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