A retrofit of a 15-year old, manually operated Microstar gantry CMM at CS Tool Engineering in Michigan, has speeded electrode inspection times tenfold. The retrofit, which took about a week and cost around $45,000, included fitting new digital encoders and adding Delcam's PowerINSPECT inspection software. It immediately solved a serious bottleneck in the company's mouldmaking process.
CS Tool produces moulds for the interior panels of car doors, floor-mounted front consoles, headliners and exterior mirrors. For years, the trend in these moulds has been toward more complex tools, often combining what had been several parts into a single component or subassembly.
"A typical mould requires 25 to 50 electrodes," Tool Engineering Manager Donald Snow claimed. "Some of the inner surfaces of the big console moulds need 200 electrodes." The large majority of these electrodes have to be checked on the CMM. Four to eight points are measured on each electrode. Before the retrofit, this took as much as ten minutes per point. In many cases, this was longer than the time needed to machine the whole electrode.
The delays were especially frustrating since CS Tool was using Delcam software to boost its productivity in engineering design, modeling and machine-tool programming. "Now we do everything off the original PowerSHAPE CAD model, including downloading surfaces to our PowerMILL CAM system for cutting the graphite and downloading those same surfaces again to the CMM for measuring," said Mr. Snow.
"We use the CMM to immediately check the electrodes against the original geometry model," he continued. "You don't have to download specially created inspection routines to use PowerINSPECT. The operator can select any set of relevant points and automatically compare each to its counterpart on the surfaces in the CAD file."
"In other words, any half a dozen relevant probed points on the CMM are as good as any other relevant set. This is important to us," Snow pointed out, "because the Microstar CMM is still manually controlled. The operator chooses which points to probe so no two sets will be precisely the same. With PowerINSPECT, that doesn't matter."
One of the biggest benefits from the retrofit is that CS Tool can take a lot more measurements. "Each measurement is about 10 times faster," Mr. Snow said. In addition, CS Tool gained a fast and unimpeachable source of dimensional data for checking finished parts for those rare occasions when a customer shows up at the door with a problem he thinks was caused by something CS Tool did or didn't do.
"Before the retrofit, the operator could only inspect dimensions in one axis at a time," Mr. Snow remembered. "The other two axes had to be locked down. Inspecting in the Z-axis required locking down the X- and Y-axes. Inspecting in X meant locking down Y and Z, and so on. This was very time consuming because it meant going back to the CMM again and again."