Coating thickness → thread fit (GO/NO-GO)
Will the plated thread still gauge? Estimate the pitch-diameter growth against the class allowance before you plate.
Why plated threads reject
Electroplating builds on the thread flanks and grows the effective pitch diameter by about 4× the coating thickness. If that growth exceeds the class allowance |es|, the plated part fails the GO gauge. This tool estimates the limit; confirm with the actual gauge and ISO 965 for the exact pitch.
6g has an allowance (undercut) that leaves room for coating — the usual choice for plated fasteners.
NO-GO — over size
The growth exceeds the allowance. Cut the threads to 6e (or 6g if you were at 6h), reduce the coating thickness, or plate before final thread rolling.
Pitch-dia growth (4 × t)
32 µm
Class allowance |es|
28 µm
Max coating for this class
7 µm
For internal threads (nuts), plating reduces the effective size, so nuts are usually tapped oversize (e.g. 6AZ) or re-tapped after plating.
Reference estimate — confirm with the gauge
- •The 4× rule and the |es| values are references; exact es comes from ISO 965 for the specific pitch and class.
- •Coating thickness varies around the part (thicker on threads/edges in barrel plating) — measure on the thread.
- •Always confirm fit on real plated parts with the production GO/NO-GO gauges.