Metal finishing Q&As since 1989

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Metallising of oil expeller worm flights for improving life [India]

June 29, 2010

We would like to know which material is to be sprayed on oil expeller worm flights to increase the life.The expeller worms wear out very fast and we feel a protective coating of metallising can help increase life.We have Twin Wire Spray System.Please advise which wire should be used for this purpose so that our customer gets enhanced life. We would like to have your expert advise.

Similar problem is with a ash conveyor screw.

Is it possible to reclaim worn out crankshafts using the Twin Wire Spray Metallising? What precautions should be taken for best results. Are the Twin wire spray coatings resistant to severe load which comes in crankshafts.

Gurmit Singh
Businessman - Bareilly UP, India

Cobalt based alloys with tungsten carbide particles or promoters of this compound (such as Stellite) are widely used in applications requiring a superior resistance to erosion and abrasion under high loads. They can withstand a considerable amount of corrosion too. Thickness, and thus, process of application, must be selected according to a dimensional control criteria. Coatings too thin such as PVD, would perhaps be useless. Thick weldments perhaps too expensive since they cannot be machined but have to be ground using diamond abrasives.

Guillermo Marrufo
Monterrey, NL, Mexico
July 11, 2010

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July 23, 2010

Dear Sir
Thanks for the advise. Stellite is very expensive and in India not easily available especially in small quantity. We have tried High Carbon High Chromium Wires using the Twin Wire Spray process to coat the Oil Expeller worm flights to a thickness of 2 mm. Is this process alright for increasing life of the worm flights.

Thanks

Gurmit Singh
- Bareilly, UP, India

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July 28, 2010

The twin wire process is suitable for high output applications requiring moderate levels of adhesion and little control of oxides and density in the coating. For your application you should consider a process that gives you better adhesion, very high density and low oxidation, like high energy plasma or HVOF. High carbon chromium steels are not good enough. If you cannot get cobalt, nickel-chrome alloys could be a good compromise.
Guillermo Marrufo-Monterrey, Mexico

Guillermo Marrufo
Monterrey, NL, Mexico

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July 31, 2010

Dear Sir
Thanks for the advise.Can we use cored wires of chromium carbide having composition of c-5%,Cr-22%,W-2%,V-1% Ni-3%
Alternate to this can we use Stainlessd Steel 420/430 grade
for coating of oil expeller worms.

Thanks with regards

Gurmit Singh

Gurmit Singh
- Bareilly, UP, India