Mitutoyo Metrology Class: Learning How to Operate a Digital Caliper


Hello, my name is Stefan Heinen, Product Manager
with Mitutoyo Europe in Neuss. The caliper remains,
due to its many possible applications, still the most popular device for measuring length
in production metrology. The design and metrological
features of this measuring device are set by the ISO13385-1 standard. A new edition of this standard will be published in 2019. This new edition will replace
ISO13385-1 from July 2011. The new version of the caliper standard contains in many places significant changes to the currently valid standard.
These changes will make the new edition for the user particularly interesting. For example, the new standard now includes, unlike the previous version, a table with suggestions
for thresholds in measurement deviations. However, in this video I would like to limit myself to explaining the calibration procedure for digital
standard calipers, which are, among other things, described in section 5 of this standard
in more detail. Here, on this table,
you can see the most common measuring ranges, 150, 200 and 300 mm
in their digital version, and also some normal ones, with which I can check the thresholds
of the measurement deviation. As I said before, the new standard contains in its normative Appendix B a table which, depending
on the length to be measured, provides examples of thresholds, unless supplier and customer agreed on something different. However, the appendix to this standard
also regulates the boundary conditions, which must be complied with, if you use these thresholds. In total, according to the standard, two or three
thresholds should be checked. 1. The thresholds
for partial contact with the measuring surface, 2. The thresholds for an offset, and 3., optionally,
for example, when utilizing a used caliper, the thresholds for a line contact situation. So, let me take the
150 mm caliper. First, I’m going to check the thresholds
for partial contact with the measuring surface. The standard states that at least five measuring points have to be measured. First, I’m going to
set to zero  and then take,
for example, a 20 mm gauge block. I’m now going to execute two checks, one on a measuring point as close as possible to the measuring rail, and another one on a measuring point as far as possible
from the measuring rail. Next, I’m going to take, for example, a 50 mm gauge and perform a check, but this time only
in the center of the measuring area. Last but not least, I’m moving on
to measuring points 4 and 5. For these measuring points, I’m going to use a gauge block which is at least 90% of the measuring range
of the caliper. So, in this case, for example,
a 150 mm gauge block. Here, I’m going to again take two measurements. The first measurement
as close as possible to the rail, and the second measurement as far as possible removed from the rail. In total, that’s five measuring points. Next, I’m going to check the thresholds for an offset. I have to check all measurement surfaces which are not
intended for external measurement. First, I’m going to
again set to zero. Second, I’m going to check
the measuring surfaces for the inside measurement. For this purpose, I can
use a 5 mm adjusting ring. I’m taking one measurement. Next, I’m going to check the depth rod. But first, I’m again going to set to zero. I’m then going to take a gauge block which, according to the standard, should be smaller than 50 mm. So, in this case, for example, 40 mm. Last but not least, I have the option, for example when utilizing a used caliper, to check for wear and tear
on the measuring surfaces. I can do this with a testing pin with, for example, a diameter of 10 mm. I’m going to take the testing pin
and guide it along the measuring surfaces, while applying light pressure. Next, I’m going to check
whether I can detect any wear and tear
on the measuring surfaces. As an alternative to checking
the thresholds for an offset for a depth measurement, you can also use
two parallel gauge blocks instead. This will increase
the stability of this check. For many calipers of this type it is also necessary to measure the thresholds for an offset for the step test. We have now taken quick look at the standard, with a focus on potential test procedures
to be used with digital calipers. If you have any questions, please feel free to contact Mitutoyo.

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