Published : 05/17/2022 09:21:41

If you own professional torque wrenches or torque tools, you probably know that they need to be recalibrated. What does the word Calibration mean? It indicates the regular examination of the accuracy and reliability of torque tools. You can fulfill this activity through special-purpose calibrating equipment which is normally subject to stringent monitoring. This process is essential because torque tools are precision instruments very often used in safety-relevant environments. They are expected to provide the same level of accuracy in their readings reliably over long periods of time. In order to ensure these standards are guaranteed, it is essential that examination by calibration tools takes place at regular intervals and is precisely documented. 

Furthermore, if you work habitually with torque tools, you’re surely aware that calibration processes must follow precise standards. In accordance with international regulations, torque wrenches need to be tested and certified every twelve months or every 5000 tightenings. However, in October 2017, the EN ISO 6789:2017 took effect and substituted the previous EN ISO 6789:2003 standard, thus introducing significant changes for both producers and torque tools owners. Let's look at this standard together, in order to know what to do when calibration of torque tools is needed.

EN ISO 6789:2017 regulation


The new standard consists of two parts:

  • The first part is targeted to producers and sets a number of minimum requirements that the torque tools need to meet, as well as establishing specific standard to be held by the documents accompanying the tools.
  • The second part is targeted to test labs that deal with certifications, they have to follow specific criteria to calculate the torque tools uncertainty of measurement. Additionally, torque tools testing is not carried out at 20%, 60%, 100% capacity but at the lowest value of the showed measurement range, at 60% and 100% capacity. This detail allows to check the torque wrench compliance on the whole showed measurement range, not only on a portion of it.

However, as essential as EN ISO 6789:2017 is to test torque tools precision before they enter the market, it also involves a substantial increase of testing time, which vary according to the kind of tool, the kind of plant used for testing, and so on. We are, in fact, talking about more than twice the time necessary to carry out checks and testing.


This is why Stahlwille, the well-known German brand specialized in the production of torque tools, designed and developed TORKMASTER 5, a new software, which is able to facilitate and speed up this kind of process.


TORKMASTER 5 is available for anyone that already owns a manual or motorized test bench, as well as clients who still need to purchase one. It consists of a software that is able to automatically calculate torque tools uncertainty values, drastically cutting testing times. Additionally, a database will be made available for Stahlwille torque tools. This will contain the required values of uncertainty to be followed, calculated by the company using a statistical method. For any other tool brand, you will be able to calculate the statistical values after the tenth time testing the tool and its insert.

Stahlwille software TORKMASTER 5


In Mister Worker™’s catalog you will find different models of Stahlwille test benches, useful for certifying every kind of torque tools from torque screwdrivers to 3000Nm torque wrenches. These are highly professional test benches of extremely high quality, produced in the Stahlwille plants in Germany and subjected to strict quality assurance tests before being allowed to enter the market.


Stahlwille Manutork© Manual test benches are really simple to use, thanks to intuitive management software and manual operating mechanisms which allows you to calibrate, with no physical effort, torque tools up to 3000 Nm.

Stahlwille torque control benches

In Mister Worker™’s catalog you can find the Stahlwille Manutork© 7791 test bench and the Stahlwille Manutork© 7792 test bench. They have mechanical rationing up to 4000 Nm and, thanks to a special force transmitting system, they take the necessary measurements without moving the spot where the force is applied. This way, the torque wrench that is being calibrated  will stay in the same position during the whole process, thus avoiding mistakes in measurement that could be caused by a shift in the place where force is applied. What makes the Stahlwille Manutork© test benches unique is their modular structure: each user can decide how to put it together according to his professional needs.

For example, if you need to personalize your professional test bench with additional modules, in our catalog you will find the Stahlwille 7791-1 test bench extension and the Stahlwille 7791-2 test attachment for torque screwdrivers. Regarding the functioning of the latter one, the torque screwdriver is to be inserted in the square mount of the transducer and fixed thanks to the universal central clamp. The handwheel ensures a controlled application of the that the required force is applied in a controlled manner to the torque screwdriver.

Stahlwille control tool for torque screwdrivers


Stahlwille Perfectcontrol© motorized test benches, IF Design Award winners, allow you to calibrate both couples torque tools and a single one in a completely automated way: this will additionally decrease times and let you avoid any physical effort. Two versions are available: the Stahlwille 7794-2 test bench, ideal to calibrate mechanical and electronic wrenches by torque value verification; the Stahlwille 7794-3 test bench, also suited for angle - not only torque - verification.

The installation of motorized test benches is intuitive and easy to use: all you have to do is positioning the torque wrench to be tested on the bench and then simply recalling it  with the supplied software, which will automatically start the testing and calibration. If you need to calibrate a Stahlwille torque wrench, the software will automatically identify it, additionally reducing testing times.

You can also use additional modules to modify Stahlwille Perfectcontrol© motorized test benches. For example, in Mister Worker™’s catalog you will find Stahlwille torque sensors and Stahlwille lab transducers.

Stahlwille torque sensors are patented tools for torque wrenches calibration and torque screwdrivers calibration: they are highly precise, thanks to the preparation and digitization of the couple directly in the respective sensor. They can be used on their own, but they are often used as an additional component of the calibration system.

The Stahlwille transducer, specific for use in a laboratory, can also be used to calibrate torque wrenches and screwdrivers: it’s equipped with a high quality precision connector, which is self locking and unaffected by transversal forces thanks to a extremely flat structure.

Stahlwille sensors and transducers


Find out also the Stahlwille 7707 W Torque Tester Sensotork®. It is an electronic tester for torque wrenches. This article includes the following elements: transducer, a holder, a display unit and a tripod, a spiral cable, main adapter and more. The software No 7759-4, including USB hub and jack cable, makes it possible to transfer readings to the PC for documenting. While individual transducers should be recalibrated, the torque tester remains on-site for further use. Furthermore, this Stahlwille Sensotork Torque Tester has a large range of application (-20°C to +60°C).

Another tool that can be very useful for you is without any doubt the Complete Calibration System Stahlwille 7706-9PC. It includes all the following parts, that represent must-have features of the perfect calibration tool: 

  • Mechanical loader, which is required for rapid, accurate xing and operation of the torque wrench. The mechanical loader also ensures that the DIN EN ISO 6789 requirement is fulfilled, i.e. that, above 80% of the torque value, the force can be applied slowly and steadily within the time needed.
  • Transducer: its aim is to digitalize the torque applied when using the torque wrench. 
  • USB-Adaptor: the torque value is then transmitted via USB to the PC, which ensures a faultless transference.
  • Cable: it is needed for connecting laboratory transducers No 7728 to USB adaptor, with jack plug and self-locking precision plug.
  • Square drive adaptor: it’s necessary to make full use of the measuring range of the transducers
  • Software: the data received in this way can then be used to issue a calibration certicate in accordance with DIN/ISO 6789.
  • Calibration systems No 7706-9 PC

If you would like additional information about the  ISO 6789 for torque wrench calibration standard, if you need to purchase a new Stahlwille test bench or update your work tools with new Stahlwille torque tools, please do not hesitate to contact us. Our team of experts will get back to you as soon as possible and, if you would like to make a purchase, you will receive a personalized quote that will address your needs.

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