Electroplated thread tolerance

[runor]

Hello guys,

we have an M5x0,8 bolt and nut that are going to be zinc plated with a nominal thickness of 8µm. What tolerances should I use? I read that the allowance should be 4 times the plate thickness, but on the female thread the G tolerances allowance is only 24µm. Or should I sum the female and male thread allowances (for example: G=24µm, e=60µm) and this two together should be more than 2*4*8µm?

I hope you understand what I'm trying to say. Thanks for the help.

 

[Red James]

Your plating at 8 micron will change pitch diameter by (8*1.732=13.856) 14 microns, on both the screw and the nut. Add 14 to the pitch of the screw and subtract 14 from the pitch of the nut, then your parts will meet standard specs AFTER PLATING. The allowance is after plating and has nothing to do with the tolerance you need to apply to the pitch diameters.

 

[runor]

Yeah, but I need to make some kind of a "standard" for these parts, and it would be easier if I could just write M5 6e for the bolt. These are european standards, here is a calculator: Metric Thread Size and Tolerance Calculator . So this tolerance would be on the drawings meaning this should be apply before plating, also after the plating you can still assemble the parts.

 

[dave powelson]

After you've established the appropriate pre-plate, min./max. material condition tolerances...
..then furnish the plater with go/no-go thread gaging with instructions on print to
'PLATE TO GAGE'.

 

[adama]

Yeah and when it comes back and its got the gage screwed on but you can't take the gage off ever again do to plate build up on both the gage and the bolt literally plating them together rest assured the plater will still charge you.

IMHO you just cut em nice and lose and hope the plater does not fuck em up too badly!

That said i belive in metric land for havier coatings its normally the female thats relived - opened up and the male is left as is, at least with larger threaded parts being galvernised. Done this way to ensure minimum fastner cross section and thread strength, above all you need gordon to pipe in he knows lives and breaths this stuff if you can get him off NHS America

 

[dave powelson]

Yeah and when it comes back and its got the gage screwed on but you can't take the gage off ever again do to plate build up on both the gage and the bolt literally plating them together rest assured the plater will still charge you.

IMHO you just cut em nice and lose and hope the plater does not fuck em up too badly!

That said i belive in metric land for havier coatings its normally the female thats relived - opened up and the male is left as is, at least with larger threaded parts being galvernised. Done this way to ensure minimum fastner cross section and thread strength, above all you need gordon to pipe in he knows lives and breaths this stuff if you can get him off NHS America

The pre-plate thd. tolerances still have to fall within the finished thread tolerances.

Plate to gage as I'm referring to is for plater to use go/no-go thread gages as acceptance.
The gages are not plated.
Plater is not allowed to force -torque the gaging.

If the plater can't get the threads to gage--how can anybody else?
...or...just don't bother with any post plating gaging and hope that the plater didn't f**k up?