Tolerances for coated metric screw threads. 2

[Bulldogio]

Can anyone direct me to the location of the relevant ISO standards for the tolerances applied to metric screw threads that are to be coated. Coating thickness can range from 15-31 microns per coated surface. We have two situations:-
1. Coating is applied to the screw only.
2. Coating is to be applied to both screw and nut.

Any advise on the correct tolerances would also be gladly received.

Thanks.

 

[npd168]

en.....

 

[ajack1]

Does this help?

http://mdmetric.com/fastindx/inxtst.htm

 

[deanc]

http://www.bossard.com/

Try this one. Its there but you need to search.

 

[CoryPad]

ISO 965-1 ISO general purpose metric screw threads — Tolerances — Part 1: Principles and basic data lists the recommended tolerance classes for internal and external threads. It has a note stating that these are intended for thin coatings like electroplating (which are thinner than your range).

ISO 4014 Hexagon head bolts — Product grades A and B is a general product standard. It lists a tolerance of 6g. It allows for coating according to ISO 10683 Fasteners — Non-electrolytically applied zinc flake coatings, which can be a thick coating. This standard lists many thicknesses and tolerance classes that should help you.

General Motors has worldwide specifications like GMW 3302 Hexagon Bolts with Flange and Pilot Point – Heavy Series. It has a coating similar to ISO 10683 that can be up to 25 [µ]m thick. GMW 3302 lists tolerance 6e before coating and post-coating gauging according to ISO 1502 IS0 general-purpose metric screw threads - Gauges and gauging with a GO-gauge of tolerance h.

Nuts are similar to screws. ISO 4032 Hexagon nuts, style 1 — Product grades A and B lists a tolerance of 6H, and allows for coating according to ISO 10683.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[deanc]

Check to plating section of this pdf.

http://www.technifast.com/pdf/presentation.pdf

 

[Screwman]

Are you wanting to gage the parts before or after coating? That will make a difference. if you are an end user you don't really need to worry about the coating build up since it should be allowed for by the manufacturer. Remember that regardless of the coating thickness, the final thread size can not exceed the maximum material condition.