Faster profile milling cutter on the Finnish market

For almost 50 years, Takoma Gear Company in Palcano, Finland has been producing large gears and gear parts, mainly for the domestic market. With a special focus on the marine industry, Takoma has been helping customers reduce lead times and costs while meeting extremely stringent quality requirements. To continue to maintain high standards of products and services, Takoma constantly evaluates its processing and tracks the latest technological developments to improve the craftsmanship. Takoma has historically used high-speed steel hobbing cutters to cut gear teeth. In 2009, the company purchased several new machines for the production of large gear parts for ships. Slewing ring bearings with an outside diameter of approximately 2 meters (6.56 feet) are made of 42CrMo4 steel and require tighter dimensional tolerances. Takoma initially used special gear mills to machine the teeth of the slewing ring bearing, but doing so was expensive and had lead times of up to 12 weeks. In search of a better solution, the company inquired with a tooling supplier that was mainly used in other machining of parts. Jyrki Koitto, Production Manager at Takoma, said: “We have been working with Sandvik Coromant for over 30 years on tools for drilling, milling and turning. Ask them if they are interested or have developed a tool for our company's application.' After close consultation with Koitto and other Takoma employees, Sandvik Coromant engineers spent months designing and testing Process-optimized custom tools. The custom gear cutting tool is then handed over to Takoma for various trials and final verdicts, and then run with the assistance of Sandvik Coromant. It produces similar results to the original tool, but at a slightly lower cost. What's more, the tool turnaround time using Sandvik Coromant is less than a week, compared to 12 weeks for the original tool. This gives Takoma more flexibility in responding to customer needs. In addition to this, while working with Sandvik Coromant on the project, Takoma also learned of a new gear milling cutter, CoroMill 170, that it thought could be used for other purposes. CoroMill 170 is used to optimize the milling of large gears in modules 12-22, previously machined by indexable inserts and HSS tools. The performance of the tool is greatly improved by the strict tooth profile design and the provision of a firm insert seat. Takoma chose to use a 300 mm (11.81 in) tool to machine a marine gear with a diameter of approximately 2.5 m (8.2 ft). The part is machined with 34CrMo4 steel. Takoma previously used 230 mm (9.06 in) HSS hobbing cutters to cut gears. When machining at 25 m/min (82 ft/min) and a feed rate of 0.12 mm/rev (0.0047 in/rev), the tool required 1,260 minutes per part. By using the CoroMill 170, Takoma was able to increase the cutting speed and feed rate to 126 m/min (413 ft/min) and 0.20 mm/rev (0.0079 in/rev), respectively. This reduces cycle time by nearly 60 percent, so that it takes only 510 minutes to machine a single part. Koitto said: “We have been using the CoroMill 170 now and it is a huge time saver. The reduction in processing time has also allowed us to reduce the turnaround time for our customers. We used to take five weeks to process an order and deliver the final product, but Now it only takes four weeks to provide the same service.” In addition to serving customers more quickly, the productivity gains from the CoroMill 170 have resulted in annual cost savings of 20,000 euros.