Ford's Non Destructive Evaluation Laboratory (NDEL) sits in a non-descript white concrete building in the middle of the test track next to its Livonia, Michigan, transmission plant. Behind the 4 ft-thick walls (8 ft behind the x-ray receptors) and 2 ft-thick ceilings are 9.0-million kV and 4.5-million kV x-ray machines, and a CT scanner. It is equipment more associated with hospitals than manufacturing plants.
"Our main focus is looking for porosity and holes in castings, scanning supplier parts, and making models from x-rays of older parts drawn on pre-CAD or earlier CAD systems," says Dave Gerke, team leader at the NDEL. He claims taking a detailed CT scan is much faster than running a part through a coordinate measuring machine–"It's six hours versus four days"–and though the resolution is not as fine, "50 microns is OK for a casting with 1-mm-thick walls." If finer resolutions are needed, x-ray film with a resolution to 25 microns is used, though the preference is to save the image electronically at the lower resolution when possible.
This technology is used to scan Ford GT engine blocks prior to its delivery to Ford's Romeo, MI, niche engine line. Ford used the same technology to look inside a Model T engine in order to create a CAD file from which new blocks could be cast for its centennial celebration. (See The 1914 Model T. That was then...& still is now
) The speed of this process is such that the lab is now involved in the annual certification process each Ford manufacturing facility must pass. "It takes three to four months and the use of hard gauges for bores and other critical parts to complete this process," says Martin Jones, NDE technical expert. Conversely, NDE scans the parts so that 3D models can be made and verified against the print. "It only takes us about four days to get the job done," says Jones, "and we have a confidence level greater than 90%."
The information gained can be shared with everyone involved in a project, including suppliers. In one case, the NDEL x-rayed a six-speed automatic transmission under load (there's a dynamometer located in the scanning room), and was able to show the casting supplier the effect of unseen casting defects on flow through the forward, reverse, and neutral circuits of the valve body. "We caught that at the start of the program, and not three months into full production," says Gerke. The NDEL's portable x-ray unit also is being evaluated for on-line weld inspection of frames in a program with Dana. "The idea is to verify the welds are to specification, contain any faults that might otherwise slip through, and reduce the amount of cash that's held while waiting for traditional inspections to take place," he says. To which Jones adds: "We don't mind fixing problems, as long as we know what the root causes are. Chasing symptoms wastes time and money."
Other programs currently underway include checking plastic parts for unseen failures, making sure sand-castings are packed correctly, and creating 3D models that can be used in analytical models. It's a lot of work for a four-man operation working 18 to 20 hour days over two shifts, running at 98% of capacity, and that strives for a two-day turnaround from shipping dock to data. But it's worth it: the average savings created by the NDEL is about $75,000 per event. In addition, non-Ford projects occasionally run through the lab, and include everything from a 500-lb. titanium side panel casting made by Boeing for the F-22 fighter jet, to helping the National Transportation Safety Board determine whether or not delamination of the vertical stabilizer on American Airlines flight 587 was the cause for its fatal crash in New York in November of 2001. Says Gerke: "It's never boring around here."