DIGITAL CALIPER   0 - 500 mm CALIBRATION

A digital caliper is an accurate measuring instrument when used with thought and care. the purpose of the calibration below is to ensure the highest degree of possible accuracy when the caliper is used for various tasks and in different ways. A uniform measurement pressure is a necessity for reliable, accurate measurement results with a digital caliper. A FMS caliper pressure device ensures a uniform measurement pressure by all users.

Measurement accuracy of a digital caliper as specified in DIN 862

Information  
As the specified requirements to accuracy are subject to a  normal distribution curve of results from calibration measurement, then approximately 85% of all new calipers will be accurate to withing half of the specified fault limit. This means that with correct use,  the majority of new calipers will be accurate to within 0,01 mm up to 100 mm.
  Repeatability accuracy for a digital caliper is 0,01mm

N.B. There is an allowance of 0.02mm for the internal jaws and depth measurement.
 i.e. Measurement inaccuracy for internal and depth is 0.04mm as opposed to 0.02mm.

Measurement length (mm)

Fault limit (mm)

Up to   100  
Up to   600  

0,02
0,03

Before starting the calibration the caliper should be cleaned - especially the measurement surfaces. The sliding jaw must move easily, evenly and without slack within the entire measurement length. The caliper and reference components must be acclimatised to the same temperature - preferably normal room temperature.
Measurement point No. Max. caliper measurement length (mm) Remarks Information
150 300 500
1 0 0 0 If the caliper's calibration is carried out  "by the book", then measuring blocks assembled to the values shown on the left be used.


It should be noted that if measuring blocks are used, then the jaws of the caliper will be alligned due to the parallelity of the blocks. A round, ground component (e.g. a plug gauge) with a known diameter should also be used as this will show wear or slack on the caliper jaws.

The sliding surface of the caliper beam should be regularly oiled using a cloth with a drop of oil on it. This will ensure  optimum movement. The caliper sliding jaw must move easily, evenly and without slack.

It is surprising that no caliper manufacturer or caliper standard gives a max. and/or min. movement and measurement force. Even with identical digital calipers from the same manufacturer this can vary. The terminology most often used is that there should be "a suitable" or "a uniform" measurment force and how much that should be is apparently up to the user.
2 12,9 37,9 42,9
3 22,8 47,8 102,8
4 41,4 81,4 131,4
5 55,1 105,1 185,1
6 67,6 142,6 217,6
7 75 165 265
8 90,3 190,3 310,3
9 107,7 207,7 357,7
10 120,2 245,2 400,2
11 142,5 252,5 425,5
12 150 300 500

There are as yet no national or international caliper calibration standards dealing with the new, and often very accurate, generation of digital calipers. Calipers with a display in 0,001mm can be purchased, but their accuracy (compared with regular 0,01mm display accuracy), without use of a constant measurement pressure is unknown. Any information on this subject will be greatfully received.
 
Caliper

Calibration Positions