Metal finishing Q&As since 1989

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Standard for dimension with powder coating or other process

2005

Hi ,

Can you clear our doubt on this.
If there a drawing for a metal or plastic with Secondary process to be done with specifying " Dimension after Plating" etc
Should we produce parts without taking this process into consideration and check the dimension after stamping or moulding and proceed to the secondary process after QA approval of stamped parts.
Is it a international standard that drawing should stated this clause .
Is drawing dimension is deem to be after secondary process even when drawing did not specific :Dimension after Powder coating " etc.
Knowing that powder coating do not give a even surface all round ,then how is this resloved.

Thank you,

Simon Aw
Ges - Singapore

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2005

Hi Simon,

My opinion if drawing don't specify dimensions to be before or after coating is: you will deliver the parts to your customer plated/powdercoated, right? So dimensions obtained by your customers' incoming inspection/quality control include coating.
Normally, a good powdercoating not exceed 100 microns (4 mils). But it depends upon your customer requirement. You must check individual tolerance for you to know if you need to compensate for the coating thickness. Example, punched hole spec is 5.0 +0/-0.08. So you should not punch the hole 4.92 because after coating, you might get as high as 5.12mm. Also your powdercoating line must have proper control of thickness.

Don Mar
- Bangkok, Thailand