can scale cause blister on parts after being chrome platted?

[ht3jyx]

we heat treated some parts (4130) and then send to platter to chrome plating. after platting, a few parts have blister. platter claims that it is caused by the heavy scale on parts, and the scale was formed by baking the stamping oil into the parts in the heat treating process.

We start to wash parts before heat treating but the blister still occurs.

any comments? does the scale really cause blister? or can platter wash offer scale before platting?

 

[arunmrao]

After washing the parts free of oil,you should have sand blast the parts to have a clean surface before attempting to plate.

" All that is necessary for triumph of evil is that good men do nothing".
Edmund Burke

 

[TVP]

If the parts have scale that cannot be removed with normal alkaline cleaning, this means that the heat treating process is causing oxidation to occur. Stamping lubricants can be easily removed by cleaning, but heat treat scale must be removed by acid pickling or mechanical descaling (shot blasting, etc.). I suggest you have an acid pickling or mechanical descaling step added to the pretreatment prior to plating.

 

[IRstuff]

Well, what do your people say? HAve you done an analysis or even a cross-section? How do you know it's not just bad surface prep at the plater?

TTFN

FAQ731-376