Manufacturer Decreases Cutting Time With Carbide Bandsaw Blades

Modern Machine Shop, Nov, 2001

When its vendor could no longer keep pace with demand for cut stainless steel rounds, A&N Corporation, a supplier of high vacuum flanges, valves and fittings for the telecommunications and semiconductor industries, brought the cutting operation in-house. A&N operates around the clock five days a week in order to maintain adequate inventories to offer same-day shipping to customers. Soon after setting up the in-house saw shop, however, manager Greg Hurst could see that his output rate of 1 sq. in./min. was inadequate. At that time the company was using bi-metal bandsaw blades on a single HEM HA 130 DC saw.

Secondly, but of no less importance, says Mr. Hurst, "We weren't getting enough square inches out of each blade." Using bi-metal blades to cut 3/8- to 1-inch thick slices of Type 303, 304 and 316 stainless steel was causing A&N to change blades twice a day. "That's a half-hour wasted," explains Hurst, "and still we were getting only 6,000 square inches per blade."

That was when A&N agreed to a trial run of the Bahco Milford 3868 Triple Set Xtra carbide blade from Bahco Tools, Inc (Scranton, Pennsylvania). The Triple Set has a high, unset raker tooth (with chamfered edges) located dead center and two lower unchamfered teeth, set left and right. These teeth are tipped with a special grade of carbide that can cut the most difficult materials and withstand high impact without breaking or chipping. The blade's geometry uses a 10-degree positive rake on the tooth face to allow for freer cutting and improved swarf clearance. Its deep gullets help to minimize clogging and distribute feed forces more evenly among fewer teeth, thereby maximizing penetration into workpieces.

Using the Bahco 3868, A&N reduced its blade changeovers from twice daily to once every three to four days, an increase in blade life of 500-700 percent. Its output per blade increased from 6,000 sq. in. to 13,000-18,000 sq. in., and its cutting time went from 1 sq. in./min. to 4 sq. in./min.

A&N now operates five bandsaws and "runs a Bahco blade on every one of them," says Mr. Hurst. The vacuum components manufacturer uses the carbide blades to cut stock ranging from 6 to 14 inches in diameter. Mr. Hurst's crew uses the Bahco Milford 3854 PHG Sandflex King Cobra ground tooth bi-metal blade, however, to cut stainless steel rounds of 6 inches or less. The 3854 is designed for upper end bi-metal production cutting applications that do not require or are not suitable for carbide. Examples include less rigid machines, those cutting difficult materials at or near their workpiece size limits, or workshops that do not require fast cuts.

The Bahco Milford 3854 PHG's tooth design uses ground rather than milled teeth, enabling much tighter tolerances on set height and tooth height. This translates into better blade performance, smoother cuts and longer life. The 385 bi-metal blade has repeating groups of high-set teeth that take a slightly thicker chip than the teeth that precede and follow them. This allows for more aggressive penetration on high tensile and work hardening alloys. The blade's low-set teeth help prevent the high teeth from overloading and breaking. Ground tooth bi-metal bandsaw blades allow users to speed up production and throughput by reducing costly downtime due to blade changes. Averaging 70 percent longer blade life, ground band saw blades are said to cut quieter and straighter than milled blades.

While the Bahco Milford 3854 PHG doubled A&N's output over competitors' bi-metal blades, Mr. Hurst is now contemplating the standardization of Bahco Milford carbide blades on all five saws. He believes that the 3868 Triple Set's higher cost will be more than offset by a boost in output to 17,000 sq. in. per blade. Mr. Hurst credits the blades' fatigue-resistant spring steel backing with boosting throughput speeds by 75 to 100 percent. He explains that the backing withstands flexing better than other blades he has tried.