X-ray inspection is an invaluable part of Ford’s Materials Technology Centre as it strives to develop new materials and components for tomorrow’s cars. Since the removal of the open X-ray system, large lead-lined room, and wet plate film-processing laboratory from the Materials Science Department in 1999, X-ray inspection has been outsourced on an ad-hoc basis. However, since acquiring one of the latest developments in real-time X-ray inspection technology, the HMX 225 ST from X-Tek Systems last year, the department has not only reduced the cost of having to send components and systems to external test houses, but is expanding the use of X-ray non-destructive testing (NDT) in automotive inspection across a broad range of applications.
How Dependent is Ford on X-Ray Inspection?
The quality and quantity of X-ray inspection work Ford are now completing is a quantum leap ahead of what they were achieving before. The old X-ray room was used about four to six times a year for projects lasting for between one and two weeks, while the real-time X-ray system is used virtually every day. The time spent using the system is highly dependent on the aim of the investigation, material type and number of components, but typically most investigations are completed within one to two days if a few components are being inspected and computed tomography is not required.
Advantages of Computer Controlled X-Ray Inspection Equipment
A key feature of the HMX 225 ST system is image quality The microfocus X-ray system uses a very finely focused X-ray beam, with a focal spot size of less than 5 microns required for the generation of high magnification and high resolution images. Furthermore, unlike wet film technology, no chemical development is needed so images can be acquired in a fraction of the time and artificial features cannot be introduced during the development process.
Speed and Convenience Associated with Computer Controlled X-Ray Inspection
One area in which speed of delivery is a key factor is in the investigation of development components that have failed during proving ground and rig testing. There is often considerable pressure to determine the cause of such failures as quickly as possible, particularly in light of the increasing need to reduce vehicle development times. While conventional film-based X-ray systems or other evaluation techniques could easily take hours or even days to determine the cause of a fault, the real-time X-ray system provides a crystal clear image within minutes. In a commercial environment this speed of delivery can save considerable amounts of money. For example, Ford was able to use the system to determine an investigation into a prototype component within four hours and resolve a potential issue, preventing inconvenience to customers.
What Materials Can be Analysed by X-Ray Inspection
The range of materials and components that Dunton deals with every day includes metal castings, metal sheet, powertrain components, polymers (including leather, seating, interior and exterior plastics), rubber, fasteners, chemicals, fluids, paints, and advanced materials, such as carbon fibre, composites and adhesives. Until recently many components were routinely sectioned on arrival in the department to allow detailed visual inspection. Now, in a growing number of cases, Ford engineers are using the X-ray system to carry out faster and more cost-effective test inspections.
X-Ray Inspection as an Internal Inspection Technique
Destructive methods can sometimes destroy crucial evidence and dismantling assemblies can disturb evidence of the root cause of a problem. Because X-ray enables you to see inside virtually any object without destroying it, Ford engineers can view inside an assembly prior to open examination for a root cause investigation. One area in which this benefit is proving invaluable is in obtaining information on the condition of catalyst bricks throughout their life. As part of the development process, prototype vehicles are crash tested. The X-ray system provides a method for internally inspecting a component to determine the effect of the impact without dismantling it, which avoids the possibility of destroying or masking vital evidence.
Engineers are also increasingly using the system to test components both before and after they have undergone integrity tests. They can compare the pre- and post-test images precisely on screen, and easily determine if any changes have taken place. Components and assemblies under test can also be viewed at different angles in 3D using the system's integrated computed tomography software. The system takes multiple X-ray scans of the image under inspection at different angles. For the highest resolution images, radiographs taken as little as one quarter of a degree apart can build up a highly detailed 3D image dataset, which can generate a range of images within 90 minutes. The calibrated images can then be used by Ford engineers to measure the size of anomalies such as cracks, inclusions, voids, or porosity within solid structures, with the highest degree of accuracy.
The system’s flexibility and ease of use has allowed Ford engineers to use it for a far higher proportion of non-destructive testing of materials, components and assemblies than ever before, including the inspection of rapid manufactured castings for prototype vehicles, components from potential suppliers before the parts (plastics mouldings, ignition coils) enter production, and prototype composite components for quality comparison purposes. In fact, 75% of the work now being carried out at the centre is in applications that were not envisaged for the system when it was first bought.
The Future for Real-Time X-Ray Inspection
From low-density materials such as plastics, to high-density metals, real-time non-destructive testing at Ford is providing an invaluable insight for every section of the Materials Science Department. Ford is now looking at ways of expanding the use of X-ray inspection for mechanisms, using the real-time capability to reveal the hidden operations of internal parts of motors,
valves and sprung components.