Slip Gauges

Slip Gauges

Slip Gauges

These may be used as reference standards for transferring the dimension of the unit of length from the primary standard to gauge blocks of lower accuracy and for the verification and graduation of measuring apparatus. 

Slip  gauges  with  three  basic  forms  are  commonly  found,  these  are rectangular, square with center hole, and square without center hole.

Wringing or Sliding is combining the faces of slip gauges one over the other. Due to adhesion property of slip gauges, they will stick together. This is because of very high degree of surface finish of the measuring faces.

Classification of Slip Gauges:

Slip gauges are classified into various types according to their use as follows:

1) Grade 2:

          It is a workshop grade slip gauges used for setting tools, Cutters and checking dimensions roughly.

2) Grade 1: 

          The grade I is used for precise work in tool rooms.

3) Grade 0: 

          It is used as inspection grade of slip gauges mainly by inspection department.

4) Grade 00:

          Grade 00 mainly used in high precision works in the form of error detection in instruments.

5) Calibration grade:

          The actual size of the slip gauge is calibrated on a chart supplied by the manufactures.

Gauges blocks are used for:

1. Direct precise measurement, where the accuracy of the work piece demands it.

2.For checking accuracy of vernier callipers, micrometers, and such other measuring instruments.

3. Setting up a comparator to a specific dimension.

4. For measuring angle of work piece and also for angular setting in conjunction with a sine bar.

5. The distances of plugs, spigots, etc. on fixture are often best measured with the slip gauges or end bars for large dimensions.

6. To check gap between parallel locations such as in gap gauges or between two mating parts.

Manufacture of Slip Gauges

The following additional operations are carried out to obtain the necessary qualities in slip gauges during manufacture.

i. First the approximate size of slip gauges is done by preliminary operations.

ii. The blocks are hardened and wear resistant by a special heat treatment process.

iii. To stabilize the whole life of blocks, seasoning process is done.

iv. To get the exact size of slip gauges, lapping operation is done.

Normal Set

Slip gauges of the following dimensions are available in this type of set.

Range	Step	Pieces
1.001 to 1.009	0.001	9
1.01 to 1.09	0.01	9
1.1 to 1.9	0.1	9
1 to 9	1	9
10 to 90	10	9
	Total	45

Selection of Slip Gauges

Standard procedure is followed in selecting slip gauges. It should be such that minimum number of slip gauges is chosen for combination of blocks depending on the type of set available. The procedure will be clear if we explain it with an example:

Let us consider the case where we have to arrange a dimension of 56.421 mm and normal sets of slip gauges are available.

Always the last decimal point is to be considered first, i.e. 0.001 mm. Since gauge of 0.001 mm is not available, 1.001 mm slip gauge is to be selected.

The dimension left now is 56.421 – 1.001 = 55.42 mm.

Now considering the second decimal place, slip gauge with 1.02 mm height is selected. The dimension left is 55.42 – 1.02 = 54.4 mm.

Next for 54.4 mm, slip gauge with 1.4 mm is to be chosen and then 3.0 mm gauge. Finally, 50 mm gauge is to be chosen.

Thus, we have 50.000 + 3.000 + 1.400 + 1.020 + 1.001 = 56.421 mm. All these five slip gauges are wrung properly to get the required dimension.

If special set of gauges be used, the combination in this case would have been 50.000 + 5.420 + 1.001 = 56.421 mm.