An integrated dye penetrant inspection flow line

Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Article publication date: 1 June 2004




(2004), "An integrated dye penetrant inspection flow line", Aircraft Engineering and Aerospace Technology, Vol. 76 No. 3.



Emerald Group Publishing Limited

Copyright © 2004, Emerald Group Publishing Limited

An integrated dye penetrant inspection flow line

An integrated dye penetrant inspection flow line

Keywords: Aerospace, Components, Testing, Inspection

Johnson and Allen recently started their largest dye penetrant inspection system to date. The project is partly funded by the dti and will run for a maximum of 2 years.

Dye penetrant examination of aerospace components is a well-established and proven technique. This new integrated flow line will detect surface-breaking flaws or fatigue cracks (whether a result of cyclic stress in service or unacceptable levels of stress during production machining).

With the introduction of high speed machining and improved tool-cutting rates using damping and other recently researched methods, it has become practical to produce a single larger component to replace an assembly of smaller components. This has generated a requirement for a larger inspection system on a scale seldom seen before. There are also new demands to improve the integrity of inspections (especially with litigation levels reaching an all time high). To do this requires the monitoring and recording of all variable parameters throughout the inspection process, ensuring every component has its unique process history.

The company is developing the software and hardware needed to address this requirement.

Already nicknamed “big brother” by its engineers, the system will record all aspects of the penetrant test, producing a test history with over 70 parameters addressed and recorded.

Based on 1.4 m long component trays, which are identified electronically by the computer, the system undergoes an initial integrity check using test panels or known defective parts.

When an operator initially loads a tray with components, component details such as part number, batch no. and part ID are entered. A test regime is selected which is the most appropriate for the components in question. At this point, the operator can adjust penetrant soak times, oven temperatures and drying times as well as many other parameters.

The components are processed semi- automatically with the computer ejecting the trays from stations, e.g. soak tank, oven, etc. at each stage. If at any time the test criteria are likely to fall outside the specification required, on-screen prompts instruct the operator to rectify the situation, making sure the test remains valid.

A report is finally generated and stored in a “Windows” type database. The integrity check is cross-referenced to individual component reports. When both the integrity and component reports are produced they fulfill all the documentary evidence required by leading aerospace manufacturers proving conformity to specified test. The reports are definitive.

The system is to be placed with the Aerospace Manufacturing Research Centre (AMRC) in Sheffield – a consortium of companies and research establishments including Boeing and the University of Sheffield. These companies/ establishments are pooling their knowledge to reduce machining times using the latest high speed cutting techniques. Their ultimate goal is to economically produce large aerospace mono-block components (replacing two or three piece sub- assemblies).

The AMRC has plans to build a new development near Sheffield, on reclaimed British Coal land and commence production of large aerospace components using their newly developed methods.

Although this equipment will be semi- automatic in nature, the system programmes have been written to ensure monitoring recording and printing will be possible, even on smaller manual penetrant lines. It is believed that future customers can benefit from this investment in technology which, according to the manufacturers, makes a very sophisticated system within reach of a modest budget.

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