The normal rule of practice requires 10 % of product tolerance to divided between the ‘GO and NOGO”gauges. For plug gauges, a plus tolerance is applied to the GO member and a minus tolerance to NOGO member. Ring gauges receive reverse tolerance direction so that the GO member is a minus an the NOGO is plus tolerance. Applying this result practice results in gauge tolerance always being included in the part tolerance by up to 10%. This results in the possibility that 10% of good product could fail inspection that no bad product would ever pass.
GAGEMAKER’S TOLERANCE CHART (PLAIN PLUG & RING GAUGES) |
|||||
ABOVE
|
TO & INCLUDE
|
CLASS XX
|
CLASS X
|
CLASS Y
|
CLASS Z
|
0.010″
.254mm |
0.825″
20.95mm |
0.000020″
0.5µm |
0.000040″
1.0µm |
0.000070″
1.75µm |
0.0001″
2.5µm |
0.825″
20.95mm |
1.510″
38.35mm |
0.000030″
0.75µm |
0.000060″
1.5µm |
0.000090″
2.25µm |
0.00012″
3.0µm |
1.510″
38.35mm |
2.510″
63.7mm |
0.000040″
1.0µm |
0.000080″
2.0µm |
0.00012″
3.0µm |
0.00016″
4.0µm |
2.510″
63.75mm |
4.510″
114.55mm |
0.000050″
1.25µm |
0.0001″
2.5µm |
0.00015″
3.75µm |
0.00020″
5.0µm |
4.510″
114.5mm |
6.510″
165.35mm |
0.00065″
1.625µm |
0.00013″
3.25µm |
0.00019″
4.75µm |
0.00025″
6.25µm |
6.510″
16.35mm |
9.010″
228.85mm |
0.000080″
2.0µm |
0.00016″
4.0µm |
0.00024″
6.0µm |
0.00032″
8.0µm |
* Table 1, pg. 4 of ANSI B89.1.6 2002 specifications