Since 1939 Cleveland-based Ferrotherm Corp. has been supplying aerospace manufacturers with gas turbine honeycomb seals and shrouds, including customers like GE, Pratt & Whitney, Rolls-Royce, the U.S. Dept. of Defense, among others. Though it’s not a high-production operation, with 121 employees and more than 100 machines, Ferrotherm is set up to perform most operations and processes on-site at its 78, 000 sq ft shop.
The operation’s batch varies in total up to 20 pieces, which are manufactured on numerous types of equipment. Ferrotherm uses CNC turning equipment, CNC milling and drilling machines, TIG welding equipment (that can process all metals including nickel and cobalt alloys), and programmable CMMs to ensure consistent quality of accurate components. The high-tech operation also has an approved metallurgical laboratory on-site.
Producing many individual components, each requiring multiple machining operations, Ferrotherm has a critical need for efficient changeover and set-up methodologies. Although the company had been using Seco tooling for over 15 years, events in 2008 brought the companies closer together.
First, Jim Owens joined Ferrotherm as an applications engineer. Next, Seco’s regional manager Matthew Gluntz began to call on Ferrotherm. Subsequently, Ferrotherm earned “preferred supplier” status from a large and strategic customer, which required it to improve its product throughput while maintaining product quality. Gluntz assured Ferrotherm that Seco could provide the tooling and support necessary to help them meet the new and more demanding objectives and together the companies developed a structured working format and scheduled regular review meetings to identify key issues and develop action plans.
“As luck would have it,” Gluntz recalls, “Seco was developing an innovative technology that had potential application to Ferrotherm’s operations.” While typical turning operations rely upon an insert engaged in a workpiece being flooded with coolant from one or more coolant delivery pipes, the new process — called Jetstream Tooling™ — offered optimal coolant delivery via a patented coolant inducer. The resulting, high-velocity ‘jet stream’ precisely targets the friction zone between the cutting edge and the workpiece, providing superior lubrication, cooling, and chip removal.
Super-alloy materials, which are typically used in aerospace applications, are poor conductors of heat. This not only results in high temperatures at the point of cut, but also has a tendency to compromise the cutting edge very quickly, increasing the likelihood of component damage.
Jetstream Tooling was applied first to Ferrotherm’s roughing operation for a ring air seal made of Inconel. A Doosan V740T CNC twin-spindle turning lathe was selected for the initial tests, and multi-directional tools (MDT) were selected to rough machine the operation.
The team tested various Seco insert grades to see if they could identify an optimal combination for the new tooling, finally settling on PVD-coated micrograin CP500 that consistently performs in difficult applications. Coolant pressures on the test machine were in the 80-150 PSI range. Because Jetstream Tooling coolant is delivered close to the cutting edge, this PSI was enough to keep the chips cool and move them away from the workpiece.
With the new tooling setup, Ferrotherm adjusted the cutting speed, the spindle speed, and the feed rate while depth of cut and length of cut remained constant. This not only resulted in improvements in the metal removal rate (from 0.92 to 1.42 cubic inches per minute), but a 35% reduction in machining time. Most important, as Ferrotherm applied the tooling to various components, all the initial tests came out positive, typically achieving an increase in surface footage of more than 50%.
After the success of the Jetstream Tooling on the Doosan, the team decided to try the same technology on a You-Ji 1600mm Vertical Turning Lathe, which already was equipped with high-pressure pump capability. With a slight modification of the feed rate, the machine’s productivity more than doubled.
Ferrotherm is now in the process of equipping a Doosan 840, which has an advantage over the You-Ji in that it is fully enclosed to contain the mist created by the high-pressure jets. Until the new Doosan 840 is up and running, the Doosan 740 and the You-Ji will be kept busy with Jetstream Tooling applications, which works well on all types of nickel-based alloys and cobalt-based components.
Seco is continuing to test the Jetstream Tooling process, experimenting on harder super alloys and implementing different grades to help optimize the operation. Given the high-speed capability of the You-Ji, Seco’s TS2000 grade has been very effective for turning super alloys, enabling higher cutting speeds and increasing productivity while lowering manufacturing costs.
Jetstream Tooling is not only providing a substantial increase of productivity in roughing operations, but new applications will continue to provide numerous cost-saving opportunities for Ferrotherm.
