CAM Program Halves Selector Fork Production Time

The abilities of CAM software have expanded so quickly that users may be forgiven for not knowing to use it to its fullest capabilities. Hewland Engineering, maker of transmission systems for race cars, had been using the Vero Software (verosoftware.com) Edgecam program to produce 95 percent of the transmission system parts that comprise the company’s core business—complex parts with tolerances of between 5–10µm. Hewland was satisfied with part quality if not the speed and cost of production. 

It took a new production engineering manager, Dominic Prinsloo, to show the company that it was already in their power, via Edgecam, to improve both. For example, producing a gearbox selector fork previously had a cycle time of 65 minutes. Under Prinsloo’s tutelage, the cycle time was slashed to 38 minutes, with lower tooling costs as well.

“When I came to the company the system was to input the values manually, which was time-consuming and prone to error,” Prinsloo says. “Now, the code is generated by associating the toolpaths to the features, so whenever the component is upgraded to the next version and the model manipulated—such as a particular diameter being changed from 32mm to 45mm—we just regenerate the feature and the toolpath changes automatically.”

Under Prinsloo’s guidance, the company began bringing in solid models for programming and generating the features from the model. They also began to use profile features, either generated from the Edgecam Features Find function or generated manually. 

He also introduced Edgecam’s Waveform roughing strategy to Hewland, both for their milling and turning cells. Previously, when milling their range of gear selector forks from EN 36 case hardening steel, “the step cutters only lasted for three parts before having to be replaced.” 

Using Waveform, the selector forks were machined at a rate of 2.8 m/min at 4,200 rpm with a 10 percent stepover, which has reduced the number of tools required to cut the component. 

Shop floor workers were wary of Edgecam’s Waveform strategy at first, worrying that the ramped-up feeds and speeds would break the cutting tools. “I introduced it slowly, starting with a low revolution, then gradually increased it until we got to a 10 percent stepover and 2.8-meter feed,” Prinsloo explains.

The cycle time has been reduced by 20 minutes on stage one machining and by 7 minutes on stage two machining—"which means we’ve saved around half an hour on each fork, Prinsloo says. “And we cut around 23 billets per carbide instead of three.”