Threaded Component Clearances

The effective diameter of an internal thread will be reduced by the same amount. When specifying minimum coating thickness, if must be done in mind that because of processing tolerances, coatings will be thicker than the specified minimum. Additional clearance to that shown by the calculation must therefore be given to ensure there is no interference when upper coating limits occur.

Increase in effective diamater = 2BC = 2t/(sin0/2)
Increase on ISO Metric, UNF and UNC threads = 2t/(sin60 deg./2) = 4t
(angle 0 = 60 deg.)

Thread clearances required if both male and female threads are coated

Thread clearances required if both male and female threads are coated

Microns	Inches	Thread Clearance in Microns
10	0.0004	240
15	0.0006	240
20	0.0008	240
25	0.0010	240
30	0.0012	360
35	0.0014	360
40	0.0016	360
45	0.0018	360
50	0.0020	360

• Microns to mm x 0.001 (to Inches x 0.00004)
• mm to Microns x 1000 (to Inches x 0.03937)
• Inches to mm x 25.4 (to Microns x 25,400)