Gear maker solves tool puzzles

END USER: Schafer Gear Works, (574) 234-4116, www.schafergear.com.
CHALLENGE: Increase chip control and prolong tool life when producing gears.
SOLUTION: Switching inserts.
SOLUTION PROVIDER: MSC Industrial Supply Co., (800) 645-7270, www.mscdirect.com.

Cutting costs while maintaining or increasing throughput is a near-ubiquitous goal for part manufacturers. This may be most pressing in job shops, where part quantities vary substantially and every incremental boost in productivity means increasing capacity for additional work and maintaining a competitive advantage.

Gear manufacturer Schafer Gear Works, South Bend, Ind., faced two distinct machining challenges when trying to increase productivity. One involved poor chip control when turning a forged steel shaft. “Stringers” wrapped around the part and cutting tool, slowed production and posed a safety hazard. The other was unacceptable insert life in a long-running job—an abrasive cast iron component for a golf cart geartrain—which involved turning 35,000 parts a year.

Seeking potential solutions and informed application expertise, Manufacturing Engineer Mike Lyman asked for help from Schafer Gear Works’ longtime tool provider, MSC Industrial Supply Co., Wood Dale, Ill.

Schafer Gear Works turned to MSC Industrial Supply when looking for solutions to manufacturing challenges.

Dean Opdycke, MSC metalworking specialist, checked all of Schafer Gear’s machining parameters on its CNC turning centers to ensure the company was running cutting tools at the optimal level for the materials involved. Opdycke then used his assessment to recommend ways in which Schafer could adjust the use of its existing cutting tools or switch to a new tool to control chips.

The shop was turning cold-drawn forged steel shafts at 600 sfm (183 m/min.) with a feed rate of 5.69 ipm (144.53 mm/min.) at a depth of 0.05 " (1.27mm) for each of the two 11.25 "-long (285.75mm) passes on the 4.025 "-dia. (102.24mm) parts. In the straight cut on relatively soft (less than 35 HRA) steel, unbroken chips remained an issue. “We were getting quite a bird’s nest of wire in the machine,” Lyman said.

MSC provided several inserts to test, including two Hertel tools. One was a HC125T-grade, DNMG-432 insert coated with TiCN/Al₂O₃. The C5/C6-carbide tool has an L5 chipbreaker, which MSC Senior Sales Account Manager Tom DeLater said is designed for medium cutting applications. The tests also indicated that an increase in feed rate to 6.26 ipm (159.00 mm/min.) would aid chip control.

“From the operator’s perspective, when he opens the door and there are sharp strings of metal hanging off the turret and the part, his first chore is to get that mess cleaned up so he can reach into the machine to take the part out without cutting himself,” Lyman said. “With the Hertel inserts, when the operator opens the machine there’s no waste there—he just takes the part out.” In the tests, only the Hertel insert provided the desired result.

In addition to increasing operator safety, the improved chipbreaking of the Hertel insert saved time otherwise spent removing tangled chips, and eliminating the impact of chips on the inserts contributed to an increase in tool life from 55 to 150 parts per tool. In addition, the Hertel insert cost 35 percent less than the tool it replaced. Finally, the higher feed rate boosted productivity 10 percent, reducing cycle time by 15 hours annually.

One of the long chips, or “stringers,” that plagued Schafer’s turning operation is surrounded by more manageable chips.

The shop’s goal for the golf cart gear application, on the other hand, was simply to extend tool life. The short-chipping nature of the malleable cast iron workpiece meant chip control was not an issue, but insert usage figures, compiled through the facility’s inventory management vending system from MSC, indicated heavy consumption of turning inserts.

The golf cart component measures 4.75 " (120.65mm) in diameter and each of the four turning passes is 1 " (25.4mm) in length. MSC assisted in testing a variety of insert brands and styles at the same cutting parameters. Again, the choice was a HC125T-grade insert from Hertel, this time a CNMG 432.

Tool life significantly improved. Insert usage for the 35,000-part annual production decreased from 220 inserts to about 145. Parts completed per insert edge increased from 40 to 60, representing 80 more parts produced per tool (20 times four corners). In addition, the Hertel tool cost 20 percent less than the previous tool.

“In cases like these, we work in close collaboration with our customers, serving as an extension of their team, to assist them in becoming more productive and efficient for the overall growth of their businesses,” MSC’s DeLater said.