Fixtured Servo Nutrunner System : Maximum Precision for Automated Assembly

As manufacturers continue to automate their production lines, fastening systems must become an integrated part of the machine rather than a handheld tool.

The ESTIC ENRZ Fixtured Servo Nutrunner System is designed specifically for automated assembly equipment, robotic workcells, and multi-spindle tightening machines. By combining a high-performance AC servo motor with an integrated torque transducer and advanced controller, the ENRZ Series delivers the highest tightening accuracy within ESTIC’s product portfolio while providing complete process monitoring and traceability. 

Unlike handheld nutrunners, fixtured nutrunners are permanently mounted onto automated equipment, allowing manufacturers to achieve consistent, repeatable tightening independent of operator skill.

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Designed for Automation
The ENRZ Series is built for fully automated production environments. Typical integrations include:

  • Cartesian screwdriving systems 
  • SCARA robots 
  • Six-axis industrial robots 
  • Multi-spindle tightening machines 
  • Rotary indexing machines 
  • Transfer lines 
  • Special purpose assembly machines 

Because the tightening process is completely controlled by the automation system, every fastening cycle is performed with exceptional consistency while reducing production variation and improving product quality.

Highest Tightening Accuracy


Among ESTIC’s tightening systems, the ENRZ Series provides the highest level of tightening performance.
 Using closed-loop servo control with continuous feedback from integrated torque and angle sensors, the controller monitors the entire fastening process in real time. 

Unlike conventional DC tools that simply stop at a target torque, the ENRZ controller continuously evaluates:


  • Torque 
  • Angle 
  • Tightening time 
  • Torque rate 
  • Tightening sequence 
  • Seating condition 
  • Abnormal tightening behaviour 


This allows production defects to be detected immediately, helping prevent defective assemblies from progressing to the next manufacturing stage.

Built-In Self Diagnosis
Reliability is critical in automated production.
Before every tightening cycle, the ENRZ system automatically performs self-diagnostic checks on key components including:

  • Torque transducer 
  • Angle sensor 
  • Servo motor 

By continuously verifying the condition of these components, the system maintains tightening accuracy while reducing the risk of undetected hardware failures affecting production quality. 

Wide Torque Coverage

The ENRZ Series supports one of the broadest torque ranges available within a single fixtured tightening platform.

Available tool units cover approximately:

  • 0.5 Nm to 3,000 Nm 
  • Straight configuration 
  • Offset configuration 
  • Bent configuration 
  • Custom angle-head configurations 

This wide product range allows manufacturers to standardize on a single fastening platform across multiple production processes. 

Complete Traceability
Every tightening cycle can be recorded together with:

  • Torque result 
  • Angle result 
  • Torque curve 
  • Tightening program 
  • OK / NOK judgement 
  • Product ID 
  • Work order 
  • Date and time 
  • System error history 

ESTIC’s management software and data logger allow tightening data to be stored, searched, monitored, and exported for quality analysis, supporting complete production traceability and continuous improvement initiatives. 

Typical Applications

The ENRZ Series is widely used in quality-critical automated assembly including:

  • Automotive powertrain assembly 
  • Electric vehicle battery production 
  • Chassis assembly 
  • Steering systems 
  • Suspension systems 
  • Industrial equipment 
  • Heavy machinery 
  • Aerospace components 
  • Multi-spindle assembly machines 
  • Robotic fastening cells 

Why Choose the ESTIC ENRZ Series?

The ENRZ Series is the preferred solution when manufacturers require:

  • Fully automated tightening 
  • Maximum tightening accuracy 
  • Multi-spindle synchronization 
  • Robotic integration 
  • Advanced tightening strategies 
  • Complete traceability 
  • Industry 4.0 connectivity 
  • Zero-defect manufacturing 


By integrating the fastening system directly into the production machine, manufacturers can achieve exceptional productivity while maintaining the highest standards of assembly quality.