Even today, in the age of computer-controlled measuring machines and contactless measurement techniques, millions of internal threads all over the world are tested every day using "gauges". After all, that has always been the most rational method.

Thread gauges are subject to international standards and are produced in very narrow tolerance ranges. The main advantage of "gauging" is that, rather than just recording individual dimensions, testers can obtain information about the overall effect of a thread in no time at all.

In terms of overall effect, a thread meets the quality standards of ISO1502 (DIN 13) if the go side of the thread gauge can be screwed in fully, without any particular effort. In contrast, it must not be possible for the no-go side to be screwed in more than 2 turns.

However, these formulations contain the only weakness in standardized testing using gauges: The specification "without any particular effort" may be interpreted differently depending on the tester because the standard does not define any quantifiable limits for the screwing-in torques.

In practice, test series have given rise to deviations of more than 100% when gauges are used manually. These deviations may lead to substantial variances in inspection severity from tester to tester and from day to day – with inevitable consequences ranging from time-consuming discussions between vendors and customers to the rejection of entire batches!

This is precisely where the OmniTURN thread testing device comes in. In order to prevent such spreads, OmniTURN is fitted with pre-set slip clutches. These articulated slip clutches, classified after thread gauges in terms of their tripping characteristic, guarantee a constant inspection severity. Thanks to the motorized drive, thread tests are simultaneously speeded up by a factor of 10 while testing costs are cut to the same degree.

Another criterion in thread testing is the depth of the go thread because, in practice, thread depth is increasingly specified as a free size, i.e. with a tolerance of just +/-0.2mm. In order to adhere to these tolerance limits, you need suitable depth measuring devices with a resolution of 0.01 mm that can be combined with the gauge, such as those used with OmniTURN. When it comes to specifying the thread depth, it is particularly important to take account of the definitions and determinants laid down in DIN2244 (May 2002).

Do you have any further questions? We would be delighted to help you solve problems in the area of thread testing. Please don't hesitate to contact us!