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exceptionally long cable, typically 1 km, between the accelerometer and indicating or recording instruments without deterioration of signal quality.

The low noise levels achieved by the design allow great flexibility of signal processing. The electrical isolation of the case from the signal line minimizes the effect of ground loop potentials and enhances immunity from radio frequency interference.

The two wire, screened connecting cable, carrying both dc power and signal, is connected to the accelerometer by a two pin 1260 connector. Mounting of the accelerometer is by a single stud, metric or imperial, and the top of the case is a 20 mm hexagon to allow easy installation using a standard AF spanner.

In addition to the standard 1060 accelerometer, special versions including intrinsically safe and IP65 sealed types are available.

Environmental Equipments Limited, Fleming Road, London Road Industrial Estate, Newbury, Berkshire RG 13 2DE, UK

Automated X-ray inspection

Continuous interpretation of real-time images can be monotonous and exhausting, leading to missed defects or false rejects. Alumetall, a major manufacturer of aluminium wheels, has recently installed a fully automated X-ray inspection system for their wheel inspection line. Designed and manufactured by Philips Industrial X-ray, the MU 35 F system was tested on 6J15 aluminium wheels. The results showed that 100% of the defects were detected, and the inspection time was found to be comparable with conventional operator interpretation.

Automatic inspection of an aluminium Philips Industrial Automat ion

Demands for inspection accuracies approaching 100% are required for safety critical components and are also becoming necessary to safeguard against manufacturers' product liability. Inspection staff are required to interpret and analyse large amounts of real-time information in short periods of time. Subjectivity and the delicate nature of the images make 100% accuracy nearly impossible to achieve. Automating the interpretation of X-ray images with the MU 35 F system removes subjectivity as the interpretation is carried out purely objectively by machine. Consequently, all components passed by the system meet the required specification.

The system is designed to be easily adapted to a wide variety of component geometries and inspection requirements. In this application, for example, the image analysis algorithms can be easily adapted to other types of wheels.

Another feature of the MU 35 F system is its fully automated capability of identifying mould origin. Each wheel is identified with a unique barcode that

wheel using the MU 35 F X-ray system from

corresponds to a particular mould. The barcode is identified and the respective inspection program loaded automatically. This allows wheels of different sizes and from different moulds to be conveyed in random order to the inspection system.

Philips Industrial Automation, York Street, Cambridge CB 1 2SH, UK

Thermal imaging for loss prevention surveys

A thermal imaging system has been purchased by European Risk Management for its loss prevention and risk management consultancy service. The new Thermovision 480 from AG EMA Infrared Systems will be used as a preventative maintenance tool to detect overheated components prior to failure in electrical, mechanical and process equipment surveys.

Risk management, including loss prevention, is a major part of ERM's business and infrared thermography has an increasingly important role to

160 NDT&E International Volume 25 Number 3 1992

wNew equipment play in this service. In their experience, approximately one third of all equipment losses are electrical in nature and about one quarter of these losses are caused by loose connections. On average, about eight electrical problems or hot spots are detected on each survey, and of these, four are minor or intermediate, and four are serious or critical - based on their temperature rise above normal or above that of related objects.

The Thermovision 480 wil l be used in applications where single unit imagers are not as suitable. Because the THV480 has a separate control unit and scanner, it can be used to inspect confined spaces which would normally prohibit the use of one larger combined unit. A top mounted LCD screen on the control unit also enables colour images to be viewed at a glance out in the field.

AGEMA Infrared Systems, Arden House, West Street, Leighton Buzzard, Bedfordshire LU7 7DD, UK

Improved ultrasonic transducers

Advances in materials, the growth of quality and safety requirements and the demand for faster inspection speeds are forcing industry to seek more effective and powerful inspection systems. This is particularly true in high technology areas such as aerospace and nuclear energy.

To help meet this demand, the French company Sodern and Philips Electronics Laboratories have combined their medical ultrasonics expertise to develop a range of ultrasonic transducers and inspection systems for N DT.

The new sensors are made from a piezo-composite material. They are highly

A range of the piezo-composite ultrasonic transducers developed by Sodern and Philips Electronics Laboratories

damped, with large bandwidth and high sensitivity, which provides high axial resolution, reduced dead zone and good contrast.

The use of composite materials enables the transmitting surface of the transducer to be easily formed to the required shape. This avoids the need for acoustic lenses which attenuate the ultrasonic signal.

Thorough testing of a sample often requires the use of more than one sensor. One solution is to group a number of sensors into an array and to carry out focusing and beam steering electronically. Simple arrays can be annular or linear, and complex arrays can be manufactured to give improved resolution and inspection speeds.

Signal processing is carried out on the transducer outputs to improve resolution by the use of dynamic focusing, for example, or to reduce the noise produced with certain 'multidiffuser' materials and to display the output so that defects in the sample are easy to identify.

Sodem, 20 avenue Descartes, 94451, LimeiI-Brevannes C~dex, France

Stress analysis for air crash investigations

Investigation of the mechanical stresses which caused a repaired pressure bulkhead to fracture, leading to the JAL disaster in 1985, has resulted in a call to establish retirement conditions for ageing aircraft.

The call was made by the National Aerospace Laboratory (NAL) in Tokyo, who have carried out extensive research to discover why the bulkhead failed and what countermeasures could be taken to maintain structural integrity.

NAL has undertaken experimental work to simulate service Ioadings and has investigated the mechanical stresses introduced by using a full field measurement technique pioneered in the UK by Ometron Ltd. This technique permits non-contacting measurement of mechanical stress by making use of the thermoelastic principle. In so doing a pictorial image of stress distributions across large sections, such as aircraft

NDT& E International Volume 25 Number 3 1992 161