Ford finds new uses for X-ray inspection

Ford is pioneering the use of the HMX ST real-time microfocus X-ray inspection system for a wide array of nondestructive testing applications across a wide range of components and materials.

The Materials Technology Centre of Ford Motor Company's world-leading Technical Centre in Dunton, Essex is pioneering the use of X-Tek Systems' HMX ST real-time microfocus X-ray inspection system, for an astonishing array of nondestructive testing (NDT) applications across a wide range of components and materials used in today's and tomorrow's cars.

Although Ford has used X-rays for NDT for many years, when the Materials Science department was refurbished and upgraded four years ago, the decision was made to remove the open X-ray system, large lead-lined room and wet plate film-processing laboratory.

While X-ray inspection was an invaluable part of the department's research, especially for metal castings, the equipment needed to be updated.

From that time X-ray inspection was outsourced on an ad-hoc basis.

Nevertheless the engineers at Dunton kept an eye open on developments in real-time X-ray inspection equipment.

In early 2001 they approached X-Tek Systems, as the leaders in microfocus real-time X-ray imaging technology, with a view to purchasing one of their systems.

(Microfocus X-ray systems use a very finely focused X-ray beam with a focal spot size of less than 5um required for the generation of high magnification and high-resolution images).

The decision was made to purchase one of X-Tek's largest, most powerful and most flexible cabinet systems the HMX 225 ST, complete with computed tomography (CT) software.

The range of materials and components which Dunton deals with everyday includes: metal castings, metal sheet, powertrain components, polymers (including leather, seating, interior and exterior plastics), rubber, fasteners, chemicals, fluids, paints and corrosion and advanced materials such as carbon fibre, other composites and adhesives.

The drive within the department to acquire the compact and self-contained X-Tek system had come from the metallurgical section, mostly driven by their previous experience of X-ray imaging for NDT applications and their desire to improve on the wet film technology.

But within a few weeks it quickly became apparent that it would provide invaluable insights to virtually every section of the department, including low-density materials such as plastics as well as the higher density metals.

Ford engineers have found that 75% of the work they use the X-Tek machine for now is actually in applications that they never envisaged when they first bought it.

The old X-ray room was maybe used between four and six times a year for projects lasting for between one and two weeks.

This real-time X-ray system is used virtually every day.

What is more, they achieve better images in a fraction of the time it used to take using film, so the quality and quantity of X-ray inspection work they are completing is quite simply a quantum leap ahead of what they were achieving before.

Having their own in-house system means that the marginal operating cost of operating the machine is very small and nothing like the cost of having to send components and systems to external test houses.

Speed of delivery is a further key factor in the utility of the real-time X-ray system.

The Ford engineers have to investigate development components which have failed during proving ground and rig testing.

There is often considerable pressure to determine the cause of such failures as quickly as possible especially in the light of ever reducing vehicle development times.

This is a further area where the X-Tek system has proved itself many times over.

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 provides a crystal clear image within minutes.

In a commercial environment this speed of delivery can save considerable amounts of money.

In one recent example Ford was able to use the X-Tek system to determine an investigation into a prototype component within four hours and resolve a potential issue, preventing inconvenience to customers.

So flexible and easy to use has the X-ray system proved that Ford has now found that it is using it for a far higher proportion of nondestructive testing of materials, components and assemblies than ever before.

Until recently many components were routinely sectioned on arrival in the department to allow detailed visual inspection.

In a growing number of cases investigations start with radiography, often resulting in faster and more cost effective test inspections.

The Ford engineers are now looking at ways of building X-ray inspection into many of their testing routines.

Nondestructive testing offers further advantages as destructive methods can sometimes destroy crucial evidence.

Dismantling assemblies can disturb evidence of route causes - with the X-Ray system Ford engineers can view inside an assembly prior to open examination for a route cause investigation.

Because X-ray enables you to see inside virtually any object without destroying it, Ford is using it more and more for testing of components both before and after they have undergone integrity tests.

Engineers can compare the 'before' and 'after' images precisely on screen and easily determine if any changes have taken place.

In fact, a further area in which Ford is expanding the use of X-ray is for mechanisms, where real-time imaging can reveal the hidden operation of internal parts of motors, valves, and sprung components.

X-Tek's customer support service has also played a key role in helping Ford to develop its use of the system.

As the machine is used more and more, Ford engineers have quickly identified ways in which they want to change and upgrade its operation and X-Tek has been excellent in responding to their changing needs.

For example, the company customised the software to enable Ford to save radiographs together with the voltage and current settings of the X-ray gun and a project reference number to ensure an accurate, traceable and repeatable record is kept of all images.

Ford was also one of the first customers to receive the auto-focusing upgrade, which saves valuable time in refocusing the machine periodically.

Ford has also found X-Tek's Computed Tomography (CT) software extremely useful.

CT is used to give 3D images of components and assemblies under test.

For CT applications the system takes multiple X-ray scans of the image under inspection at different angles.

For the highest resolution images Ford engineers take radiographs as little as one quarter of a degree apart to build up a highly detailed 3D image dataset, which can generate a range of images within 90min.

CT offers the ability to provide a range of different types of images in either 2D or 3D.

Slice images and rendered views can be exported to standard format image files, and animation fly-bys can be generated.

Transparent 3D images can be used to show, cracks, inclusions and voids or porosity and as all the data are stored in electronic formats, it is possible to manipulate images at any time after the initial X-ray inspection has been completed.

This means old images can easily be revisited and re-rendered to show aspects that may not have been under consideration in the first instance.

CT images are also accurately dimensioned and calibrated, making it possible for the Ford engineers to measure the size of anomalies within solid structures with the highest degree of accuracy.

CT generated 3D images are also very useful for explaining the nature of material faults or problems to colleagues and suppliers, whereas as 2D radiographs need a greater level of skill and experience to accurately interpret.

Within a year of first installation the X-Tek HMX 225 ST system has more than paid for itself in the volume and value of tests that it has been able to complete simply and highly cost effectively.

The greater understanding which the Ford engineers have been able to acquire has been of even greater value.

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