EDM selected to investigate metal failures

Specialist independent accredited materials testing laboratory has selected an EDM wire machine to investigate the causes of engineering and weld failures.

Specialist independent accredited materials testing laboratory, Test House, based in Cambridge, has selected a Sodick EDM wire machine to assist it in investigating the causes of engineering and weld failures in a wide range of applications, from aerospace to marine engineering.

Set in 40 acres of rolling parkland, the Test House, a wholly owned subsidiary of The Welding Institute (TWI) was established in 1990 and provides services to clients throughout the UK and around the world.

Well known and respected for its expertise and experience in the marine, power engineering, and steam generating fields, Test House clients include Marine Flag State accident investigators, owners, insurers, loss adjusters, power plant operators and power plant manufactures.

The organisation offers mechanical testing including Rockwell, Vickers and Brinell hardness, proof loading and fastener tests, corrosion tests, and accredited metallurgical tests, as well as non-destructive testing, including X-ray (up to 100mm steel thickness), manual A-scan ultrasonic testing, and colour contrast and fluorescent liquid penetrant inspection.

In order to carry out this wide range of activities the Test House is supported by a well-equipped, dedicated machine shop for the manufacture of test specimens and fixtures and it is here that the Sodick machine is playing its part.

In the event that a structure is found to fail, a sample is sent, by the client organisation, to the Test House for investigation.

When it arrives, one of the first tasks to be undertaken is to cut the sample to an appropriate size for testing.

Naturally many of the materials that are being investigated are extremely hard and difficult to cut and any cutting undertaken must not affect the structure of the material.

For these reasons EDM has been found to be the most appropriate technology and the Test House has recently invested in a Sodick A530D wire EDM machine.

Cliff Hart, Workshop and Operations Manager, explains; "We frequently have to deal with test samples in exotic work hardenable material and alloys.

We use the Sodick machine to produce and notch fracture toughness specimens, and we find that growing the necessary fatigue crack from the EDM starter notch offers greater precision than was possible with our previous technique.

This is the first EDM machine we have had in our workshop and we have been very pleased with it - in fact it hasn't stopped working since it was installed.

In addition to producing test specimens, now that we have more experience with the EDM wire technology, we are also using it to manufacture jigs and fixtures for other areas of our operations.

It's not only very fast, it means we can now keep more work in-house, under our direct control.".

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