Gentz Industries Puts its Trust in Seco

Gentz Industries (Warren, MI) is an ISO 9001:2000 and AS9100 provider of complex turbine engine components for the commercial and military marketplace. Typically producing low volume, high-precision parts from expensive and hard-to-machine materials such as Inconel, titanium, stainless, etc., Gentz has no room for error or part-scrapping.

When Seco Tools Inc. application engineer Belinda Smith approached Purchasing Manager Mark McWilliams and asked him to consider switching to a .156-in. Seco thread mill on a combustor case component made of Inconel 718 heat-treated to 42 RC , she was met with just a bit of skepticism. "We had already tested five competitive .156 size thread mills on this application, which requires the creation of 52 #10-32 thread holes," explains McWilliams. "All resulted in tool breakage. We weren't very confident when Smith said ‘ours is better'."

To perform the thread milling operation, Gentz had settled on using a .170 thread mill, which created undersize holes. Each of the 52 holes then had to be individually hand-tapped for finishing. To perform the entire threading operation re quired two thread mills making three passes and about 15 taps to hand tap the part. Total time per component clocked in at 154 minutes of machining time plus another one to two hours for hand tapping. The process, although not greatly efficient, was very stable. The Gentz team was not very keen about mess ing with a procedure that was producing decent components, especially when you consider that the forged combustor ring is already worth $14,500 when it arrives on Gentz' floor.

"Experience had taught us that the .156 thread mill was just not suited for the job," says Jim Stevens, Gentz OEM manufacturing manager. "But, our longstanding relationship and trust in Seco finally led us to agree to try its solid carbide Threadmaster." The Threadmaster has a TiCN coating and micrograin structure that provides both increased toughness and wear-resistance as compared to other solid thread mills.

Curt Hassan, Seco Regional Manager, then insisted that Gentz more than double its feed rate from 78 in./min to 194 in./ min. Additionally, he wanted to run the machining center up to its 5,000rpm capacity; over 3x the 1,500rpm Gentz had been using. "We were very skittish about speeding up," says Stevens. "I couldn't imagine the thread mill doing anything but falling apart on the Inconel."

The result? The new Seco Threadmaster .156 was able to complete the thread milling operation in 53 minutes with only two passes, saving an hour in machining time and one complete pass. Additionally, the hand tapping time was reduced from 90 minutes average per component to 30 minutes.

To help compensate for the increased feed and speed, some process changes were made. The programming parameters were modified with Seco's Thread Milling Wizard software. This software automatically generates the machine code based on input parameters, greatly reducing setup time and creating a perfect thread from the very first cut.

And, Gentz switched from a hydraulic chuck system to a shrink fit thermal tool holding system offered by Seco. "This helped us achieve less runoff, better tool life and more even tool wear," adds Stevens. "With the machining center running at 5,000rpm, the rigidity of the thermal tool holder is critical in achieving better tool balance."

Hassan is modest about the success of this thread milling application. "The Threadmaster .156 is providing a great cost-savings to Gentz, but is not necessarily contributing greatly to increased throughput. We are only in the infancy of gaining efficiencies in the machining of this part."

"Just eliminating the hand-tap time was worth the change in this process," emphasizes Gentz COO Roger Bartolomei. "And, you can't scoff at almost $62,000/year in savings.

"We are a fast-growing company, so it is critical for us to work with suppliers that know how to help us improve efficiencies," he concludes. "One thing I know for sure, Seco understands the meaning of partnership."