ARTICLE #02
8 October 2025
Introduction
In modern coil winding, precision is not an option, it’s a requirement. Electronic tensioners represent a significant step forward in ensuring constant and accurate wire tension during high-speed and automated production.
Unlike mechanical systems that rely on manual spring adjustment, electronic tensioners operate through an intelligent closed-loop control system, capable of reacting in real-time to even the smallest variations in wire behavior.
The LTR LEMP Series embodies this technological evolution, offering reliability, repeatability, and complete integration with Industry 4.0 standards.
The Role of the Tensioner in Winding
The role of a tensioner remains the same: to maintain constant wire tension throughout the winding process. However, in high-precision or automated environments, even small fluctuations in wire tension can lead to:
- Layer deformation or uneven coils
- Overstretching and insulation damage
- Inconsistent inductance and thermal behavior
Electronic tensioners solve these issues by continuously monitoring the actual wire tension and automatically adjusting the braking force to match a user-defined set point.
Working Principle of Electronic Tensioners
At the core of an electronic tensioner lies a closed-loop feedback system. The LEMP Series by LTR works through continuous interaction between the load cell and the electromagnetic brake.
- The load cell constantly measures the actual wire tension value.
- This signal is compared to the preset tension (set point) defined by the user.
- The system then increases or decreases the braking force in real-time to maintain constant tension, even when wire speed or bobbin diameter changes.
This active feedback mechanism guarantees superior precision, typically within ±2–3% of the target value, while also preventing wire breaks or loose windings.
In other words, the electronic tensioner continuously “listens” to the wire and reacts instantly, achieving what manual regulation cannot.
Technical Advantages and Characteristics
Main Advantages:
- Constant, automatic control of wire tension
- High precision (up to ±2%) even at high speed
- No need for manual calibration or spring adjustment
- Real-time compensation for inertia and diameter variations
- Compatible with fine, enamelled, and special wires
- Integration with PLC or supervisory systems (Industry 4.0-ready)
Construction Features:
- High-sensitivity load cell sensor
- Electromagnetic brake
- Control board with PID regulation and digital interface
- Optional PC/Panel connection for monitoring and diagnostics
Application Cases
Electronic tensioners are particularly suited for:
- High-speed automatic winding machines
- Multi-spindle or synchronized production lines
- Complex winding profiles requiring dynamic tension control
- Processes where product quality consistency is critical
Industries: electrical motors, transformers, inductors, sensors, and medical micro-coils.
Process Integration and Technical Influence
Electronic tensioners directly influence process stability, coil geometry, and energy efficiency. By maintaining optimal and constant wire tension:
- Coils maintain uniform density and perfect layer stacking
- Thermal dissipation improves due to consistent wire packing
- Rework and scrap rates are drastically reduced
LTR Electronic Series Overview – LEMP Series
The LEMP Series represents LTR’s most advanced solution for electronic wire tension control. Developed from years of experience in mechanical systems, it combines mechatronic precision with industrial robustness.
Main Characteristics:
- Tension range: from ultra-thin wires (0.031 mm) to heavy wires (up to 1.5mm)
- Custom configuration for each winding application
- Built-in protection for wire breakage and overload conditions
Each model in the LEMP Series ensures precise control while minimizing maintenance and setup time.
In addition, the LEMP system provides data logging and traceability, allowing operators to analyze and optimize winding parameters for continuous improvement.