#4 | 2020
SYN] Magazin

Accreditation for machine capability tests

Machine capability tests in accordance with the standard — Atlas Copco Tools is now accredited

 “Safety-critical class A joints should always be tightened using tested tools that are fit for the purpose.”

In our interview with Emil Gümüsdagli, Business Manager Calibration Services with Atlas Copco Tools Central Europe GmbH, we clarify the most important questions concerning machine capability tests in accordance with the standard, the various requirements and codes concerned and why industrial users should test their tools regularly.

Since January 2020, Atlas Copco has been officially accredited for tests in accordance with VDI/VDE 2645-2:2014-09 with method  M201 to M208. How did this decision come about? 

The answer to this question is based on the origin of the standard itself. Before VDI/VDE 2645-2 came into effect, there was no validated procedure for the performance of machine capability tests on tightening tools. Each manufacturer defined its own procedures. In this situation, the results of the tests which were carried out were not really comparable.

Safety-critical class A joints should, under all circumstances, always be tightened using tested tools that are fit for the purpose. If accidents occur with personal injury, property damage or damage to the environment, the question of liability will certainly arise and the consequences may be very serious. It must be stated quite clearly that tool tests in accordance with internal company specifications are not in accordance with the state of the art and do not provide recognized evidence of tool capability in the event of product liability disputes.

It was this fact and the requirement for standardized tests stated in other standards and QM systems that led to the development of VDI/VDE 2645-2.

VDI/VDE 2645-2 was therefore drawn up to take into account the key aspects of quality management (e.g. in accordance with ISO 9001 or IATF 16949) as well as the provisions of VDI/VDE 2862 "Minimum requirements for the use of tightening systems and tools" and to ensure the comparability of test results. 

With VDI/VDE 2645-2, we now have a standard document that supersedes tool tests in accordance with manufacturers’ specifications. As a result of our recent accreditation in accordance with DIN EN ISO/IEC 17025, we can not only offer our automotive industry customers the best possible support for meeting the requirements of IATF 16949:2016 and VDI/VDE 2862, Part 1 but also provide all our other customers, for example in the aerospace and medical technology industries, who work on the basis of ISO 9001 ff. and VDI/VDE 2862, Part 2, with a possibility of having their tightening tools tested in accordance with a standardized procedure. 

You have just explained the origin of VDI/VDE 2645-2. We would now like to ask what this guideline is precisely about. Could you possibly give us a brief explanation in your own words?

The guideline VDI /VDE 2645-2 describes the performance of machine capability tests for the regular testing of tightening tools in production and series production, as well as the statistical methods to be used for evaluating the measured data. Among other items, the document deals with the fact that industrial production processes are subject to a variety of different influences. These influences are normally characterized in Germany by the “5 Ms”, for the German words denoting man , machine, method, material and medium environment (ambient effects).

A machine capability test verifies the stability and reproducibility of the factor “machine”, allowing an assessment of process errors to be expected as a result of machine effects. In turn, this provides a benchmark for comparing the quality of different machines. The objective of the machine capability test is therefore to ensure that only tools that are fit for the purpose are used. This fitness for purpose is assessed within the framework of the test.

For the performance of the machine capability test, we need a test bench that reduces all undesired effects such as friction and movement (machine) or observation errors (human factors) to a minimum. In addition, the target parameter “angle” can only be simulated with sufficient precision on a test bench. This is not possible with a test joint.

Currently, there is no comparable standard for the performance of machine capability tests anywhere in the world.

So “roughly speaking”, VDI/VDE 2645-2 only states requirements for the correct performance of a machine capability test. What standard actually states that industrial tool users need to carry out such tests?

Yes, that is correct. VDI/VDE 2645-2 describes regular testing in production and series production. This is therefore a test procedure. The answer to your question is rather complex as we need to consider the special rules and requirements applicable to the various industries.

Let us take the automotive industry as an example. As a result of the introduction of IATF 16949, which has already applied to customers in the automotive and component supply industries since 2016, there were growing requirements for Atlas Copco to carry out the machine capability tests previously conducted in accordance with Atlas Copco Global Standard/Service (previously MFU 25/50/100) in the accredited range in accordance with VDI/VDE 2645-2. A key aspect of quality management in accordance with IATF 16949 is that production must be carried out under controlled conditions. As a prerequisite for this requirement to be met, the factors affecting the production process and the tools used (especially the factor “machine”) must be tested. VDI/VDE 2645-2 closes a gap in this context. To this extent, standards such as IATF 16949 refer indirectly to the use of VDI/VDE 2645-2. To date, the principle was that a manufacturer could carry out the test itself if there was no (adequately) accredited test laboratory. This exception is now no longer valid  as we have been accredited for testing tools since January.

For the award of external contracts, this means that measurement equipment and tools used in quality-relevant areas must be calibrated and tested by an accredited calibration or test laboratory and “the certificate of calibration or test report shall include the mark of a national accreditation body.” 3 

Does that mean that customers can no longer carry out this test internally?

No. Under certain conditions, tests may also be carried out internally. However, internal tests must meet certain requirements in order to demonstrate that they are in accordance with the state of the art in connection with product liability disputes. In most cases, this would mean considerable investment and operating expenses. In the case of a liability claim, evidence must be provided. An independent third party then determines whether all the requirements have actually been met. This means a severe risk for the customer. The risk can be excluded if the test is carried out by an accredited external test laboratory. The leeway for non-accredited tool testing is therefore very restricted.

As I have already mentioned, the topic is highly complex. If anyone is unsure about the requirements applicable to their own company on the basis of the relevant standards, I would recommend our workshop “Machine capability of tightening tools”. This deals with the various requirements in greater detail.

Following the successful accreditation, Atlas Copco Tools is now the first manufacturer to be accredited for machine capability tests in the torque range from 1 N·m to 1000 N·m. How does the accreditation process work and who takes the final decision on accreditation?

All industrial countries have an appropriate accreditation organization. In Germany, the body responsible is Deutsche Akkreditierungsstelle GmbH (DAkkS). Calibration and test laboratories can be accredited. In order to apply for and obtain accreditation, a laboratory must meet certain requirements. Among other items, the laboratory must have a quality management system in accordance with DIN EN ISO/IEC 17025, qualified and trained personnel, test equipment fit for the purpose and validated procedures or methods. In the course of the accreditation process, the team members of the accreditation body and the specialist of Physikalisch-Technische Bundesanstalt (PTB) carry out audits to determine whether the test laboratory is fit for the purpose. If all the requirements are met, the accreditation body issues accreditation.Afterwards, that accreditation is subsequently that accreditation is subsequently verified by audits carried out at regular intervals.

What certainly helped us to meet the comprehensive requirements for accreditation was the fact that Atlas Copco had already imposed strict requirements and targets on itself in the field of tool testing. For example, we have offered tests in accordance with VDI/VDE 2645-2 since mid-2017 – but without accreditation. We were therefore all very pleased to receive the accreditation certificate at the end of January. This was the result of a sustained period of hard work with support from all the departments concerned.

As regards internal Atlas Copco requirements, what is position of the tool tests in accordance with Atlas Copco Global Standard/Service (i.e. MFU 25, 50 and 100) or tool tests in the range not accredited in accordance with VDI/VDE 2645-2?

Our tool tests MFU 25, 50 and 100 are not based on standards but are internal procedures that we have developed as a manufacturer (Atlas Copco Global Standard/Service). These internal procedures are based on VDI/VDE 2647, which covers the type testing of tightening tools – torque and torque /angle testing.

Testing in the range not accredited in accordance with VDI/VDE 2645-2 is carried out in just the same way as in the accredited range. We do not make any difference between the two types of test, except that the result report (test certificate) does not bear any accreditation mark (DAkkS logo).

This is a special feature of Atlas Copco Tools! We want to ensure that our customers use tools that are fit for the purpose under all circumstances. If an accredited machine capability test (e.g. in accordance with IATF 16949) is not called for, the customer can still decide to act in accordance with the state of the art (and Atlas Copco Tools on behalf of the customer).

“In order to meet the requirements for machine capability tests and to comply with maintenance intervals in the current situation, we also offer customers the possibility of sending more tools to our test laboratory in Essen. To make the process easier, we are very pleased to provide customers with transport boxes.
- Emil Gümüsdagli, Business Manager Calibration Service, Atlas Copco Tools Central Europe GmbH -

One last question on accreditation: Atlas Copco Tools is accredited for the methods  M201 to M208 in accordance with VDI/VDE 2645-2. What precisely are methods  M201 to M208?

We are entitled to test power tools with continuous rotation in the torque range from 1 N·m to 1000 N·m. Procedures  M-201 to M-204 are tool-related. In other words, the tool itself is tested.

Measurements are made at up to 4 test points. The number of test points depends on whether the tool is type-tested and/or whether an angle monitoring system is available. 

Methods  M-205 to M-208 are joint-related. The joint-related machine capability test is based on the process specifications of the customer. Depending on the process specification, either a torque or an angle test may be carried out. For the sake of completeness, I would just like to say that impulse tools are a special case and that implementation in accordance with the standard is only possible via our product development department in Nacka (Sweden). If tests of tools of this type are required, we will continue to offer our internal standards until further notice.

We have talked about standards in some detail. How often should tests in accordance with VDI/VDE 2645-2 be carried out?

As production must be carried out under controlled conditions in all situations, Atlas Copco (as the manufacturer) recommends that all tool tests and machine capability tests should be carried out at an interval of one year and each time maintenance work is performed or the tool is repaired. In this respect, there has been no change in our recommendations.

The accredited test laboratory is located at the Atlas Copco Tools facility in Essen. Can you also carry out tests at customers’ plants?

Yes. The Atlas Copco test laboratory is accredited both as a stationary laboratory in Essen and for tests at customers’ plants. I would like to add that we are working on the extension of our accreditation with respect to the measurement range, the procedures and other Atlas Copco locations.

Thank you very much for this highly informative discussion. We wish you and your entire team success with the work on extending the range of accreditation.

3. Excerpt IATF 16949:2016, Chapter

Further information is available here