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White Spots on Zinc Plated Cast Iron

Dear Sir,
we are facing a major problem with a machined cast iron part Material Standard Grade 25. When we plate this part which is a round thick ring (machined) we notice small white spots all over the part. Initially we thought the parts were perhaps beginning to rust before they were plated. To correct this we made sure that a good anti rust is apllied to parts right when they come off a machining center. Now too however the parts are showing white spots.

Please suggest what we need to do. We have confirmed with supplier that the proper drying time is given to all parts as they come off the line. Parts are never touching each other and they are dried using a open fanning of the parts after they come out from the line.

Can you suggest what more can be done to take care of this problem?

regards, Thanks a ton!

Preet Singh
Manufacturing - New Delhi, India
2005

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Dear Mr Preet,

It sounds like your machining lubricant is bleeding out from the pores. Find a good lubricant and ensure that the water used for dilution is STRICTLY as per the suppliers recommendation.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2005

adv.