2018cnc4-5.2

42 www.CNC-West.com CNC WEST April/May 2018 In the past, Hobbs and the com- pany’s two additional programmers would occasionally make the mis- take of removing too much materi- al during the roughing stage, which left no remaining material to com- plete finish passes. Hobbs explains that continuous verification im- provements made to Surfcam Tra- ditional over the years have created reliable programming fail-safes for users. When the company manufac- tured aluminum wheel prototypes for the Mars Curiosity rover, the project required achieving a very thin wall section and whittling 350 pounds of aluminumdown to seven pounds. The wheel required three different lathe operations, and lots of mill work, which amounted to 14 different machine setups and about 100 hours of chip time. Hobbs, who explains that ma- chining large parts is “part experi- ence and part feeling,” notes that challenges related to heat are sig- nificant hurdles in the manufactur- ing of massive workpieces. “Thermal expansion is a major challenge, so if you don’t have good temperature control, it will kill you,” he says. “We often have to do multiple roughing operations because the parts change shape and size during the process.” Hobbs and his team take advantage of the 3-and-5-axis mill- ing features within Surfcam Traditional to create their preci- sion parts, including the Z-level roughing strategy. The Z-rough cycle performs tool movements along the X and Y axes, using Z-axis increments to remove large amounts of material. Many users also take advantage of Surfcam’s Z Finish tool- path, which is capable of cutting multiple surfaces by using a two axis (X and Y) contour cycle in Z-axis increments. The Z Finish cycle is best utilized for cutting surfaces or areas that are steeper or close to being verti- cal. “Two of the biggest capabilities in Surfcam that we use are multi-surface 3-and 5-axis mill- ing, and the 3-axis roughing features,” Hobbs says. “Those cycles have been vastly improved over the years, and today you have much better gouge control, and you can cut multiple surfaces with much greater overall toolpath control.” Tapemation also uses Surfcam Tradition- al’s TRUEMill machining cycle, an optimized roughing toolpath that can be completed with a one-step 3D roughing through pre-finishing operation. The toolpath creates uniform step height across all surfaces, regardless of how many tools are used. It also removes material at significantly faster rates, and at greater depths of cut. “The three and five axis capabilities of Surfcam have come so far, and that’s really improved a lot for us,” Hobbs says. “Surf- cammakes the entire process so much easier, and we know that what’s being sent to the machine is going to result in the best possible product.” Rover wheel on the surface of Mars Hobbs with the rover wheel in Scotts Valley, Ca.