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Gage Classes: Which To Use, When?

Posted by Travers Team on Jan 12, 2021 8:00:00 AM
Travers Team

The difference between gage classes:57-062-900

The class of a gage refers to the tolerance which is allowed in the manufacturing process of the gage itself. A Class XX gage has an extremely tight tolerance for use in high precision applications, while Class ZZ gages have a lower tolerance and are more suitable for general purpose applications, with Class X thru Class Z falling between each of the aforementioned classes. With a range of tolerances available, it is critical to calculate the tolerance your application will require prior to selecting the class of the gage you use. Scroll down for tolerance table & link to downloadable guide.

Class XX Gages:

These gages have an inch tolerance of .000020" and a metric tolerance of .00051mm. They are one half of the deviation of the X. Ideal for high precision applications where tolerances are critical. (Note: tolerances vary as the diameter range changes, please see the Tolerance Table below for tolerance listings from .010" thru 12.010" and .254mm thru 305.05mm.

Class X Gages:

These gages are available with an inch tolerance of .000040"and a metric tolerance of .00102mm. These gages are used where greater precision is needed. (Note: tolerances vary as the diameter range changes, please see the Tolerance Table below for tolerance listings from .010" thru 12.010" and .254mm thru 305.05mm. See our website for Class X Pin Gages

Class Y Gages:

These gages are available with an inch tolerance of .000070" and a metric tolerance of .00178mm. These gages are used where moderate precision is needed. (Note: tolerances vary as the diameter range changes, please see the Tolerance Table below for tolerance listings from .010" thru 12.010" and .254mm thru 305.05mm.

Class Z Gages:

Class Z gages have an inch tolerance of .0001″ and a metric tolerance of .00245mm. They are one half the deviation of the ZZ for a better fit. (Note: tolerances vary as the diameter range changes, please see the Tolerance Table below for tolerance listings from .010" thru 12.010" and .254mm thru 305.05mm.

Class ZZ Gages:

These gages have an inch tolerance of .0002" and a metric tolerance of .00508mm. They are practical where good precision and speed are important. (Note: tolerances vary as the diameter range changes, please see the Tolerance Table below for tolerance listings from .010" thru 12.010" and .254mm thru 305.05mm. See our website for Class ZZ Pin Gages & Sets

 

ToleranceS:

DIAMETER TOLERANCE CHART (PER ANSI/ASME B89.1.5)

Diameter Range

"XX"

"X"

"Y"

"Z"

"ZZ"

Above - Including

INCH

.010" - .825"

.000020"

.000040"

.000070"

.0001"

.0002"

.825" - 1.510"

.000030"

.000060"

.000090"

.00012"

.00024"

1.510" - 2.510"

.000040"

.000080"

.00012"

.00016"

.00032"

2.510" - 4.510"

.000050"

.0001"

.00015"

.0002"

.0004"

4.510" - 6.510"

.000065"

.00013"

.00019"

.00025"

.0005"

6.510" - 9.010"

.000080"

.00016"

.00024"

.00032"

.00064"

9.010" - 12.010"

.0001"

.0002"

.0003"

.0004"

.0008"

Above - Including

 

 

METRIC

 

 

.254mm - 20.96mm

.00051mm

.00102mm

.00178mm

.00254mm

.00508mm

20.96mm - 38.35mm

.00076mm

.00152mm

.00229mm

.00305mm

.00610mm

38.35mm - 63.75mm

.00102mm

.00203mm

.00305mm

.00406mm

.00813mm

63.75mm - 114.55mm

.00127mm

.00254mm

.00381mm

.00508mm

.01016mm

114.55mm - 165.35mm

.00165mm

.00330mm

.00483mm

.00635mm

.01270mm

165.35mm - 228.85mm

.00203mm

.00406mm

.00610mm

.00813mm

.01626mm

228.85mm - 305.05mm

.00254mm

.00508mm

.00762mm

.01016mm

.02032mm

 

WAnt to learn more about Precision Gaging?

Download the Gaging Fundamentals Guide to learn the basics of precision gaging and secure essential reference materials including:Gaging Fundamentals

  • The types of gages.
  • The differences between each gage class.
  • Gage tolerance selection.
  • How to calculate gage tolerance.
  • Gage tolerance charts.
  • Proper gage maintenance.


Download Guide

 

Topics: Measuring & Inspection, Metalworking and Machining

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