Gleason Streamlines Automotive Gear Cutter Production

Manufacture of gear cutting tools is a complex, labour intensive procedure involving more than a dozen process steps. At the Plymouth factory of Gleason Cutting Tools, production has been rationalised and floor-to-floor time reduced following the installation of more capable machine tools for prismatic machining and mill-turning.

One key item of new plant is a Hermle C 50 U five-axis machining centre, which has taken over the work of two older machines, a horizontal-spindle profiler and a bed mill. Supplied by Geo Kingsbury Machine Tools, the German-built machine was chosen due to the generous working volume, which allows the largest Gleason cutter to be produced.

The availability of an HSK A 100 spindle option also steered Gleason towards this machine. It allows extended tooling to be used, providing sufficient clearance between the toolholder and workpiece for the gear cutting blades to be milled without interference when the component is held vertically.

According to section supervisor, Jason Norsworthy, other factors taken into account during the purchase were the competitive price of the machine and its perceived longevity.

The end product shipped from Plymouth is often not a complete cutter, but a boxed set of 15 or 16 curved steel segments carrying the cutting blades. An automotive gear manufacturer bolts the segments to an existing core disc when the previous segments have dulled.

They start life as a length of tool steel bar, from which up to 10 mm of tool steel is removed by the rigid, 60 kW-spindle of the C 50 U, which also has the precision to complete relatively demanding profiling operations to the required accuracy. For some machining operations, the trunnion carrying the table and workpiece is swung through 90 degrees and clamped so that the table and component are vertical. Productivity is high owing in part to 6 m/s2 acceleration and rapid traverse rates of 60 m/min in the X- and Y-axes, 55 m/min in Z.

Control is provided by a Heidenhain iTNC 530 enabled for Profibus digital communication and networking to Gleason's Pro/Engineer CADCAM system.

Now that the process has been established, the entire line will be shipped to the parent company's headquarters in Illinois during the first half of 2010. Engineers from the UK will be employed in the US for several weeks to ensure correct installation, knowledge transfer and smooth handover.

A Hermle C 50 U 5-axis machining centre has replaced two machines in the manufacture of automotive gear cutter segments at Gleason, Plymouth.

Workpiece probing on the Hermle C 50 U.

The trunnion-mounted rotary table and fixtured workpiece are swung through 90 degrees to complete the machining operations on the gear cutter segments.