Slip gauges , types , materials, classification, application

1. Slip gauges
Slip gauges or gauge blocks are the universally accepted
standard for length. as they are introduced by
Johansson, Swedish engineer ,called as Johansson
gauges.
They are working standard of linear dimension.
They are used for main two purpose,
a) For direct precise measurement where the accuracy
of the work piece demands it.
b) For use with high magnification comparator, to
establish the size of the gauge blocks in general use.
c) For checking an accuracy of measuring instrument

3. Slip gauges are rectangular blocks having cross section
area
9mm Χ 30mm upto 10mm
9mm Χ 35mm above
Or
10mm Χ 35mm

4. Shape : square & square with hole

5. slip gauges are available in Inch as well as in mm.
Designation of slip gauge :
a) For inch ‘E’ letter
For metric ‘M’ letter
b) On basis of number of slip gauges available in set.
Inch sets = E81,E49,E41,E35,E28
Metric sets = M112,M105,M87,M83,M50,M33,M27

6. Classification of sets:
Range(mm) Steps No of
Blocks
1.001 – 1.009 0.001 9
1.01 – 1.09 0.01 9
1.1 - 1.9 0.1 9
1- 9 1 9
10 – 90 10 9
Total = 45
M45 (Normal set)
Range(mm) Steps No of
Blocks
1.001 – 1.009 0.001 9
1.01 – 1.49 0.01 49
0.5- 9.5 0.5 19
10- 90 10 9
1.0005 --- 1
Total = 87
M87 (Special set)
Base dimension is 1 mm

7. M33/2
2mm base dimension set.
---less costly
---less likely suffer deterioration in flatness.
Range(mm) Steps No of
Blocks
2.005 --- 1
2.01 – 2.09 0.01 9
2.10 – 2.90 0.1 9
1 - 9 1 9
10,20,30 10 3
60 --- 1
100 ---- 1
Total = 33pieces

8. Wringing of slip gauges
---is thus defined as the property of measuring faces of a
gauge block of adhering ,by sliding and twisting the
gauge against measuring faces of the other gauge
blocks or the reference faces of datum surfaces
without the use of any extraneous means

9. Procedure for wringing
1) Before wringing ,the slip gauges are cleaned by a lint
free cloth ,a chamois leather or a cleaning tissue.
2) On slip gauge is then oscillated slightly over the other
gauge with alight pressure.
3) One gauge is then placed at 90° to the other by using
light pressure and then it is rotated until the block one
brought in one line.
As air expels out from mating faces gauge faces adheres
with each other partly by molecular attraction & partly
by atmospheric pressure, gap between mating surface
is nearly about 0.00635 microns

10. Slip gauge set

11. Materials for slip gauges
Slips gauges are made from
Tungsten carbide – extremely hard
wear resistant
costlier
Chrome plated
-- Good anticorrosive property with stand against frictional
wear.
--If gauge worn out, can be again plated and brought to
original size.
-- Not possible to avail gauge blocks in wring together for
longer time
High grade steel -- hard ,economical

12. Classification according to the accuracy(class of work)
Grades II :
Grade II gauge blocks
are workshop grade for rough
checks. They are used for
preliminary setting up of
component where production
tolerances are relatively wide;
for positioning milling cutters
and checking mechanical
widths.

13. Grade I :
used for more precise work such as setting up
sine bars ,checking gap gauges and setting dial test
indicators to zero

14. Grade 0 : These are inspection grade gauge blocks
used in tool room and inspection department for
high accuracy work.
Grade 00 :
These gauges are placed in the standard
room and for highest precision work. Such as
checking
Grade I & Grade II slip gauges.
Calibration Grade : This is special grade, the actual
size of the slips calibrated on a special chart
supplied with a set .the chart must be referred
while making up dimension

15. Protector slip gauges
In order to prolong life of slip gauges.
Two protector slip gauges included in set of grade ‘O’,I &
II
----Identified by letter ‘P’
---- included in set of gauge blocks of grade O,I, & II
----Available in pair of 1 or 1.5 or 2 or 2.5 mm gauge
block

16. Care of slip gauges
General care:
1) Protect all s/f against climatic conditions by applying
suitable anticorrosive such as petroleum jelly.
2) Keep slip gauges in suitable case ---separate
compartment –close case when not in use.
3) Protect gauges from dirt and dust.
4) Should not magnetized other wise they will attract
metallic dust
Preparation before use:
a) Remove protective coating applied to it with petrol
b) Clean gauges with soft lint free cloth

17. Care in use :
1) Fingering of lapped faces should be avoided
2) Handling should be as minimum as possible
3) Allowed to settle down to the room temp.
4) 20 ° temp.
5) Should not be held above the open case when being
wrung together
6) When not in use gauges should not kept on s/f plates
for longer time with measuring face resting
7) Standard procedure of wringing should be followed
8) Wringing , any sign of roughness or scratching is felt
then wringing should be stopped and faces examined
for burrs or scratches.

18. Care after use :
a) Gauges should not be left wrung together for an
unnecessary length of time
b) immediately after use ……..
c) Calibration

19. Accessories of slip
gauges