Magnetic Particle Inspection
6000 Amps controlled using microelectronics
Technologies used


Industrial sector (PRODCOM code)
    332 Instruments and appliances for measuring, checking, testing, etc
Johnson & Allen Ltd, located in Sheffield and established in 1938, has expertise in Non-destructive Testing (NDT) techniques. The company designs and manufactures standard and bespoke Magnetic Particle Inspection Equipment for the Aerospace, Petrochemical, Automotive, Offshore and other Industries. Electronic work was subcontracted. Direct employees total 25, non have microelectronic experience. Annual sales turnover is 1.5MEur. The Industrial Sector is 3320: Instruments and Appliances for testing.

Magnetic Crack Detection requires the control of large currents, typically up to 6000Amps AC RMS. This is achieved by controlling the primary windings of purpose built transformers using two Thyristors for larger units above 1500Amps or a Triac for smaller units below 1500Amps. The two circuit boards used in the existing equipment were designed by the sub-contractor and have been used for approximately 10 years. They operate similar to an AC Motor Controller. A low voltage is applied in bursts to the Thyristor or Triac to make it 'fire'. The current is then controlled by chopping the waveform.

The project was to replace the existing product with an integrated electronic testing machine that had an improved performance, functionality, flexibility and accuracy.

The new product, which uses microelectronics, is individually programmed to give a choice of either automatic or semi-automatic testing of a broad spectrum of components A magnetic field in the test component is set up by a known and accurate current waveform to identify imperfections. The precise regulation of magnetising forces is achieved with a feedback loop that monitors the current. Monitoring of the current uses back to back Hall Effect Probes to enable highly accurate calibration and ensure test integrity and repeatability. A non-volatile memory is used to enable relevant test parameters for individual components to be retrievable and eliminate manual set up.

The project started August 1997, took 13 months and cost 45KEuros. The payback on this investment is 12 months and return on investment is conservatively estimated to be 10-fold over the life of the product. 325 words.
Johnson and Allen Ltd.
Neocol Works,
Sheffield, S3 7AR
United Kingdom

Detailed information

You can also benefit from microelectronics

Microcontroller technology provided Johnson and Allen Ltd. with the means of improving its products and enhancing its market position. You can also achieve significant benefits by acquiring the right microelectronics technology and utilising it in your product or manufacturing process. You can get help from FUSE to realise this.

FUSE is a technology transfer programme, funded by the European Commission to stimulate the wider use of microelectronics technologies by European enterprises to increase their competitiveness and enhance their economic growth. The demonstrator described here is one of many examples in the public FUSE portfolio covering the whole spectrum of microelectronics technologies and spanning a wide range of applications and industry sectors.

FUSE provides you with:

  • Best practice in acquiring specific microelectronics technologies and conducting full development projects through the FUSE portfolio of real life demonstrator documents.
  • Local training and expert support to plan your innovation realistically and help you conduct your project successfully.

Further information and support relating to this and other demonstrators can be obtained from the addresses below.

Further information   Guiding Technology Transfer Node
For further information and support regarding this case study, please contact a Technology Transfer Node (TTN) in your region.
Homepage: http://www.fuse-network.com

Bolton Institute of Higher Education
Technology Development Unit
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