10% Product Tolerance Rule ASME B89.1.5:1998 p 4.1
The 10% product tolerance rule is commonly used in the manufacturing
industry. It is considered a "rule-of-thumb" which means
that it is a suggestion or a starting point. You, as the engineer,
may use the 10% product tolerance rule, or deviate from the 10%
product tolerance rule, as long as you can justify your decision
to your management.
To calculate the gage tolerance using the 10% product tolerance
1. Calculate the full tolerance of the product feature.
2. Calculate 10% of the product feature tolerance to find the
full gage tolerance.
3. Divide the full gage tolerance in half to find the gage member
(Otherwise stated: Product Tolerance x 0.05 = Gage Member Tolerance)
Standards that relate to gage design decisions:
ASME B18.104.22.168 Guidelines for Decision Rules: Considering Measurement
Uncertainty Determining Conformance to Specifications
ASME B89.1.5 Measurement of Plain External Diameters for use as
Master Discs or Cylindrical Plug Gages
ASME B89.1.6 Measurement of Plain Internal Diameters for use as
a Master Rings or Ring Gages
These standards are available for purchase from ASME
The tightest tolerance for plain cylindrical gages which is feasible to be used to test parts is X. Tolerances XX and XXX plain cylindrical gages should not be used to test parts. Tolerances XX and XXX are better suited for master gages; not working gages. When the part tolerance becomes tight enough to warrant the use of XX or XXX plain cylindrical working gages; then Air Gages need to be considered as the better alternative.
When tolerance XX or XXX are supplied; we do not argue with the manufacturer’s certification. It is difficult to get two calibration laboratories to return identical calibration results for tolerances XXX plain cylindrical gages. With tolerance XX we should be able to gain agreement between different calibration laboratories; however; the test method needs to be identical and the uncertainty needs to be ignored.
This data is provided for general information only. The intention
is to provide accurate information; regardless; errors may exist
in the supplied information. If accuracy is critical, base your
final decisions on the data provided in the root document: ANSI/ASME
B89; which is a copyrighted document. To purchase a copy visit
an Authorized Reseller.
Original Posting: 2/28/2008
Last Revision: 6/2/2015
Error corrections in, or comments about, the above data can be sent