OneCNC - Mill Expert Helps Build the Ford GT

It was the first week of March and the surface data for the new Ford GT had not arrived. With Bill Ford’s personal GT as the first to be built, and unveiled at the 100 year celebration, the April delivery date was looming closer. Suppliers for the door sheet metal, glass, and seals had already come to the table with their parts and ours was the frame that would hold the entire assembly together. Not found on the show cars that toured the country (Figure 1), the frame, or DLO, is part of the exterior styling of the production vehicle and was required to be cosmetically perfect.

Figure 1: Ford GT at North American Auto Show in Detroit

This project, with high risk and a compressed delivery schedule, was awarded to Apex Manufacturing in Troy Michigan, where we build molds for the Zinc and Aluminum die-cast industry. For our CAM system, we had been using OneCNC Mill Pro with great results because it was easy to use and created effective cutter paths. However, when processing some test data of the size and intricacy in the DLO, it was evident that a few changes would make the job go more quickly.

Specifically, we needed faster code generation to enable more design, cut, check iterations, as well as an effective way to select one part feature to machine with assurance that others on the same surface would not be touched. We also wanted to leverage our high speed machining capabilities to cut the DLO’s 0.060” wide 1.200” deep B side mounting flange cavity that required a .050” ball end mill (Figure 2).

Concurrent with the planning stages of the project, OneCNC was preparing to release the Mill Expert version, which came to us just as we were ready to cut.

After loading the new software, the first thing that we noticed was that the new interface is much like the old version; menu and wizard driven, hence no training required.

Next, we set up the post processor for our machine, and after 15 minutes we were making test cuts.

Now came the acid test of importing the 50 Meg data file via the new Rhino direct import. The import was quick and the data integrity was flawless, soon we had the part moved out of In Car Position and into the machine coordinate system, and were ready to generate a roughing cutter path.

Even with a .0005 tolerance, the speed of code generation was at least five times faster than the Mill Pro version. With 4000 square inches of mold surface to cut, the time savings was substantial.

Like in the old Mill Pro version, machined part simulation provides a great tool for error proofing because it is created from the tool path and not from the original cad data. As a result, the cut simulation shows definitively what the machined surface will look like. The simulation even shows scallops related from an excessive step over distance. After simulating the first rough cut, some surface anomalies were evident, which were traced back to untrimmed surfaces and holes in the original IGES file.

To correct these problems, Mill Expert has surfacing tools such as sweeping a surface along a rail curve. These were a great time saver because we were able to make corrections without exporting back to our design package.

The compressed delivery schedule for the project made lights out machining imperative. As a result, verifying paths in the cad environment became essential, and Mill Expert has even more verification tools than the old Pro version. Features such as viewing the tool, as it cuts, with the path laid on top of the model surface, aided in the process. By rotating the model and tool path about in free space, rapids, cuts, and tool changes were all verified relative to the design surface.

This tool was especially useful when verifying how the .050” ball end mill was going to follow the surface of the deep mounting flange (Figure 2).

With feeds of 750 IPM and three days, we had 4 master patterns to produce the driver and passenger side DLO for the Ford GT.

From the master patterns, and a plaster casting process, the finished castings for both sides of the car were created a week later (Figure 7).

Figure 8 illustrates how well both detail and surface quality were represented in the finished part.

After painting, and fitting with window glass, the DLO was installed during the build process at Saleen Specialty Vehicles in Troy Michigan.

So, when time counts call on OneCNC to do it.