Hard chrome plating directly affects the geometric dimension of a component. For a shaft, the coating increases the diameter; for a bore, it reduces it. The most common documentation errors result from confusing “µm per side” with “µm on diameter” and from failing to specify whether the tolerance refers to the condition after plating or after finish machining. Below you will find a short explanation, practical guidance, and technical sections. The calculator itself is located further down the page.
The chromium layer deposits on the working surface and changes the dimension. In functional fits (bearings, seals, guideways), it is critical that the tolerance is clearly defined and refers to the correct condition: after plating or after final machining.
Specify whether you are calculating a shaft (external diameter) or a bore (internal diameter).
Provide the diameter before processing. The calculator accepts both dot and comma as decimal separators.
Specify whether the coating is given in µm per side or µm on diameter. The calculator converts automatically.
If grinding/polishing/honing is planned, enable the option and enter the allowance per side.
Enter Dnom and Tol+ / Tol− (or select IT6/IT7 as tolerance width – simplified without tolerance position letter).
Check the stage summary table, Dmin/Dmax values, tolerance margin, and recommendations (technological and documentation risks).
Calculate diameter change after hard chrome plating (µm per side or µm on diameter), include finish machining and verify compliance with Dmin/Dmax.
Status: green = OK, yellow = margin < 5 µm, red = out of tolerance.
Expert Mode: estimated process current and deposition time for a smooth cylinder (without end faces and complex geometry). Approximate result.
| Stage | Dimension (mm) | Change |
|---|---|---|
| No data | ||
The result complies with Dmin/Dmax and leaves allowance for typical process variation and measurement uncertainty.
This is a technological risk zone. It is advisable to clarify finish machining, measurement method, and critical zones.
Coating thickness must be adjusted, machining allowance revised, or the target tolerance specification clarified.
If coating thickness is specified “per side,” the diameter increase/decrease equals 2× that value. This is a frequent mistake leading to deviations of tens or even hundreds of micrometers.
For IT6/IT7 and functional fits, missing this information creates ambiguity: delivered “as plated” or prepared for finish machining.
With thicker coatings and sharp edges, the risk of edge build-up increases. Functional zones and acceptable areas should be clearly defined in documentation.
At minimum define: dimension, tolerance, coating thickness, tolerance reference state, and for friction/sealing applications also surface roughness and required inspection protocols.
The structure below reduces the risk of misunderstandings. The calculator generates a similar specification automatically based on input data.
Finish machining (grinding / polishing / honing) is usually justified when stable fits, controlled roughness, or interaction with seals and guides is required.
If coating thickness is given in µm per side, shaft diameter increases by 2× thickness. For a bore, diameter decreases by 2× thickness.
Yes. Chrome deposits uniformly on the circumference, therefore bore diameter decreases by 2× thickness per side.
For precision fits, tolerance is usually defined for the post-finish machining condition. Otherwise, discrepancies during acceptance are likely.
In industrial practice, this is risky. For dimensional stability and surface finish control, grinding/polishing/honing to final size is typically specified.
It does not replace proper substrate preparation. Minor irregularities may be covered, but deeper defects require regeneration and machining allowance.
Base dimension, plating zone, coating thickness, final tolerance, Ra requirement (if applicable), material and hardness, quantity, inspection requirements, and masking.
Calculator results are theoretical. Actual repeatability depends on component geometry and field distribution in the bath, fixturing method, shielding and masking, process parameters, and finish machining. Measurement method (instrument, measurement points, reference conditions) is equally important. Therefore, measurement zones and tolerance reference state should be clearly defined in documentation.
