Flexible gear milling

Gear milling is usually performed with a hob dedicated to a specific gear module. Efficiently and economically producing small to medium batches of gears that each have different modules, therefore, is a challenge, according to Nicklas Bylund, senior research engineer for Sandvik Coromant.

In response to this, the toolmaker developed InvoMilling tools and a patent-pending technique to produce spur and helical gears with indexable-insert cutters in multitask machines. The technique provides flexibility when making gears by enabling a range of module sizes, such as modules 4 to 8, to be machined using one disc-type cutter tooled with standard carbide indexable inserts.

Sandvik Coromant’s InvoMilling gear-making technology allows one cutter tooled with standard indexable inserts to produce a range of module sizes. Images courtesy Sandvik Coromant.

Another benefit of InvoMilling is the ability to machine a part complete in only a few setups—ideally one—to improve quality and reduce cost, Bylund noted. This is achieved by using 5-axis mill/turn machines for producing parts with integrated gearing, as well as stand-alone gears.

Tools are available for producing modules 2 to 16 but most applications fall within a smaller range. “Our starting focus is between modules 3 and 8,” Bylund said.