Wednesday, 12 January 2011

Aerospace Paint Adhesion Testing - Advice and solutions from Pexa

Adhesion testing is referenced in many specifications and can fall under audits for ISO9100 and NADCAP. Adhesive tape pull off testing is the usual method.

Know what specification is referenced...

Several Airbus specifications such as ABP 4-1123/4-2130 indicate that adhesion can be checked according to ISO2409 which is an important standard referenced frequently for paint adhesion testing. It is a destructive test and cannot be used on regular production

ISO 2409
Requires a crosshatch to be cut using either a single or multi-blade cutting tool. On metal substrates the crosshatch spacing is 1mm for coatings <60µ thickness (typically primer), the spacing is 2mm for coatings 61µ-120µ (typically primer plus topcoat).

The tape required in ISO2409 is at least 50mm wide and is recommended to be clear. The peel strength is 6-10 N/25mm.

In addition to these 2 items Pexa supplies the recommended magnifier together with the other items in a handy toolkit.

Airbus UK also provides for a non destructive test which is suitable for the detection of significant adhesion problems, however it can be used on regular production. The tape to b used is 3M #250 or an equivalent with peel strength >9N/25mm and elongation <5%. The tape is applied using a roller of width 25mm-50mm.

American Methods
Specifications from Boeing, Mil, ASTM, Fed and Bombardier specifications such as BSS7225 and Fed Std 14. Typically these methods require a 4½ lb roller to apply the tape, the hardness of the roller may also be indicated (Durometer 70+/-5 or 80+/-5). As of today the tape required in ASTM D3359 (Permacel 99) is not available so where this is required Pexa will be supplying the LA-26 tape which is likely to be approved instead.

The tape typically required for many of these standards is again the 3M#250

Pexa supplies all the above items. For further info please email or contact us on +44 1422 314400

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