Tightening technique

Reliable techno­logy with the highest quality

Tightening technique

Modular Struc­ture – Tailor-Made Technology

DSM offers electrical hand-held nutrun­ners and built-in nutrun­ners for manual, automated, and fully automatic assembly processes. They are charac­te­rized by their wide variety, and highest level of relia­bi­lity and precision.

DSM nutrun­ners are not only available in varied torque versions, but also with a diverse range of drive and attach­ment modules.

Indeed, it is possible to use DSM cutting-edge techno­logy for virtually every appli­ca­tion case.

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Basic Princi­ples of Tightening Technology

Tightening techno­logy is a generic term encom­pas­sing tools, systems, machines and compon­ents used in the manufac­tu­ring of detachable screw connec­tions.

What is a screw connection?

A screw connec­tion consists of compon­ents that are held together thanks to the assembly preload force with the help of:

  • Screws
  • Nuts
  • Blind rivet nuts
  • Bolts

Tightening techno­logy includes processes like screw feeding, screw positio­ning as well as the rotational and feed movements of the tool while tightening.

These functions make tightening techno­logy tools widely appli­cable in the manual, semi-automatic and fully automatic assembly.

Further it can also be used in the final assembly stages in manufac­tu­ring and proces­sing indus­tries.

Another important aspect is the poten­tial for non-destruc­tive disas­sembly for post-proces­sing, repairs or mainten­ance.

This is how it works

Screw connec­tions are secured through the static friction of the thread and additional screw-locking elements.

The main focus of tightening techno­logy is to deter­mine and set the appro­priate assembly preload force for the screw connection.

To achieve that goal the torque and angle of rotation need to be calcu­lated correctly.


An electro­ni­cally commu­tated motor (EC motor) serves as the drive.

It enables the calcu­la­tion of torque and angle of rotation using the motor control parame­ters or torque and angle of rotation measurements.

4 Advan­tages of Electro­ni­cally Operated Tightening Technology

As opposed to pneumatic tightening techno­logy, electro­ni­cally operated tightening techno­logy is not depen­dent on the availa­bi­lity of compressed air.

Further benefits include flexi­bi­lity, process liabi­lity, torque accuracy and integrity when it comes to documen­ta­tion requirements.


Thanks to the EC motor and EC tightening techno­logy, it is possible to freely adjust parame­ters such as speed, torque, angle of rotation, direc­tion of rotation and screw-in depth.

This allows every screwing process to be modified at any time.

Also, an adapt­a­tion to new requi­re­ments is always possible.

Process Liabi­lity

EC tightening systems can identify, evaluate and document the assembly process.

Torque results can be measured and evaluated through indepen­dent sensors.

This is especi­ally important when assembling safety-critical components.

Torque Accuracy

Torque accuracy is deter­mined by the critical machine capabi­lity index Cmk (capabi­lity machine katayori).

It indicates the ratio between tolerance and process spread of the machine.

The calcu­la­tion also takes into account a devia­tion of the process mean value from the tolerance center.

Usually an ability exami­na­tion is conducted, using a sample of 50 parts from a short produc­tion period.

Documen­ta­tion Requirements

Contrary to pneumatic tightening techno­logy, electro­ni­cally operated systems record the achieved torque and angle of rotation figures as a standard practice.

Hand-Held EC Nutrun­ners: Torques from 0.05 Nm to 60 Nm

Our hand-held EC nutrun­ners meet all requi­re­ments needed for a reliable assembly process.

Their compact and ergonomic design is perfect even for low torques.

Additio­nally, the highly accurate torque sensor accom­pa­nied by the DSM control system allows diffe­rent tightening proce­dures to be carried out securely and accor­ding to quality requirements.

Thanks to the ergono­mic­ally shaped handle bar (5), the nutrunner lies comfor­tably in the hand, enabling barrier-free usage of the freely confi­gurable control buttons (7).

The arran­ge­ment includes a program selector switch for switching between programs and a start button to initiate the selected program.

A status indicator (2) integrated in the handle displays the status of the tightening process: green indicates a proper fastening, yellow indicates an ongoing process and red indicates a faulty fastening.

The measu­ring unit (4) within the handle is for measu­ring and control­ling the torque and angle of rotation.

At the end of the handle there is a connector (1) for the electronic selec­tion and monito­ring of the drive.

When using vacuum screw holders, the connector also includes the air or vacuum connec­tion for an opera­ting pressure of six bar.

Additio­nally, an integrated EC converter (3) ensures quick system integra­tion and error-free setup.

Acting as decen­tra­lized intel­li­gence it trans­fers charac­te­ristic data via plug-and-play.

Tightening opera­tions can be performed even in dim light because of the additional light­ning (8) located above the drive unit (6).

Handheld EC Nutrunner Setup

Built-In EC Nutrun­ners: Torques from 0.05 Nm to 2400 Nm

Our DS series guaran­tees the best digital build-in tightening techno­logy for error-free produc­tion processes.

The main feature of this series is its compact design thus allowing perfect integra­tion into existing or new produc­tion lines.

The built-in EC nutrun­ners are powered by an electro­ni­cally controlled servo motor (2) and transfer digital data as well.

As with our hand-held nutrun­ners, an integrated parameter memory ensures an error-free setup.

Additio­nally, the entire tightening process is controlled, monitored and super­vised through the MultiPro 3D control System.

Since not every produc­tion process is the same, we offer our DS series with or without a torque sensor.

Thanks to the mounting flange (9), it is also possible to choose between various downforce units (10) such as:

  • Drive offset
  • Stubby drive
  • Angle drive
  • Self-start drive
  • Offset drive

It is also possible to exchange them quickly.

An illumi­nated panel (6) is integrated in the housing to show the user the status of the process.

Green indicates a properly executed fastening, yellow shows that the process is ongoing and red signals there is a fault.

Built-In EC Nutrunner Setup

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