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EN Plating - Bending Test for peeling off check

(-----) 2006

I need detail step with step how to perform bending test for EN-Plating on hollow pipe aluminium part, preferred with photo or drawing. What is the criteria of bending test reject.

Eric Hong
QC - AngMoKio, Singapore


Is the plating on inside or outside of the pipe or both sides? What is the pipe diameter?

The usual bending test for EN in the USA is in ASTM B733 [affil. link to spec at Techstreet], "Standard Specification for Autocatalytic (Electroless) Nickel-Phosphorus Coatings on Metal," Paragraph 9.4.1 and also ASTM ASTM B571 [affil. link to spec at Techstreet], "Practice for Qualitative Adhesion Testing of Metallic Coatings," Paragraph 3.1

To prepare specimens, cut a ring from the pipe and then cut the ring lengthwise, perhaps into 4 quarters. To test the exterior plated surface, bend a specimen over a mandrel 4x the plating thickness into a U-shape, and examine at 4x magnification. Insert a sharp probe into cracks. Separation of plating from the substrate (loss of adhesion) is failure.

For ID plated surface, suggest ASTM B571, Paragraph 3.2. Reverse bend 90 degrees from the original curvature, then return and bend 90 degrees further than original curvature. Repeat until the EN is cracked. Check for separation as above. Sorry, no photos.

Ken Vlach [dec]
- Goleta, California

contributor of the year Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.


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