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Aluminized spray to correct undersized parts

Q. Dear Sir,

We are a manufacturer of Aluminium machined components. Some of the components gets undersized by 50 micron to 150 micron. We do not want to reject the components on account of their High Value. We are looking for a method like Aluminium Spray to regain the size. Pl. suggest the method or possibilities.

Pradyumna Shah
Owner - Aurangabad, Maharashtra, India
December 21, 2011

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First of two simultaneous responses -- December 21, 2011

There are many options in the choice of thermal spray equipment and alloys. High energy systems are probably the best but cost more to buy and many have a wasteful overspray.
For small flat areas, I would do some homework with small dual wire systems such as TAFA.
Conventional "flame spray" can be ok, but you will have to have it demonstrated by the vendor. Make sure that whatever you buy that training and microsection training is included.

Choice of aluminum alloy can be as critical to the product as the equipment.

Sales people make it look simple and easy, which it is after a couple of years experience.

Forget about doing holes.

Metal prep prior to the spray is just as critical as in regular plating.

James Watts
- Navarre, Florida

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Few or no alternatives if all dimensions are out of tolerance by different amounts and the parts are very complex. If there are only some areas wrong, perhaps one or two outside diameters or one or two flat faces, you could brush plate them after a proper stop-off. If the needed build-up is all around but with the same thickness, then electroless nickel would be my first choice. These alternatives could work provided the customer accepts and an aluminum surface is not mandatory by some reason (i.e. exposure to strong oxidizing environments).
G. Marrufo- Mexico

Guillermo Marrufo
Monterrey, NL, Mexico
Second of two simultaneous responses -- December 21, 2011