Applications
Electric injection machines use direct-controlled electric motors to move the main axes, completely replacing hydraulics. They offer precision, energy efficiency and silent operation, which make them ideal for applications in high-tech sectors such as medical, electronics and micro-components. The absence of oil reduces maintenance and contamination risk, ensuring cleaner production environments.
Requirements:
Control of the granule
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Management of the Hot Runners
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Temperature control of the barrel
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Control of the moulding process
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Injection force
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Measurement of injection pressure at the nozzle
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Tie bar deformation
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Deformation of the moving platen
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Enhancing Production Data
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Requirement:
Control of the granule
Before the injection phase, the plastic pellets must be heated and dehumidified to eliminate residual moisture. Failure to do so may allow bubbles to form inside the product during the moulding process, compromising both product aesthetics and functionality.
In addition, there is the risk that wet pellets could damage the heating elements of the extrusion cylinder, greatly increasing the risk of unexpected machine downtime. Stable thermal control is therefore essential.
Solution:
The use of smart solid state relay with soft-start feature allows the progressive heating of the pellets, avoiding thermal shocks and ensuring the complete elimination of moisture. The integrated diagnostic system detects any partial breakage of the load, improving reliability and reducing machine downtime.
Requirement:
Management of the Hot Runners
The design of the material distribution channels in the mould is often one of the most critical jobs. It is essential to put as many of these channels as possible to try to obtain the most uniform distribution in the form, but, at the same time, the channels must not be too many or too small, because material that solidifies inside the form is difficult to restore to a molten state. For this reason, the management of hot runners can help in many moulding situations, heating the channels inside the mould to keep the material in a semi-liquid state.
Gefran technology for hot-runner thermal control relies on solid state relay, PID controller and thermocouples.
- Each resistor is managed in a closed loop via PID controller, integrated into the PLC or assigned to dedicated multiloop controllers such as the GFXTERMO 4, which allows the temperature to be maintained within ±0.5 °C of the setpoint.
- The GRP-H solid state relay, compact and with integrated heatsink, ensures precise control of current up to 120 A. IO-Link communication also reduces the number of I/O boards through the integrated management of commands, alarms and absorbed current.
- The solution is scalable and compatible with PIDs integrated into PLCs or remote modules.
Requirement:
Temperature control of the barrel
The heating cylinder of the injection machine works like an extruder, so correct temperature regulation is essential to obtain an optimal finished product. Temperature control is necessary to ensure the thermal stability of the cylinder, so that the system can respond quickly to variations in thermal or process load, avoiding potential defects and deformation of the polymer.
Gefran technology for thermal control relies on solid state relay, PID controllers and thermocouples:
- Each resistor is managed in a closed loop via PID controller, integrated into the PLC or managed by dedicated unit such as the 1250 device, which allows the melt temperature to be maintained within ±0.5°C of the setpoint, guaranteeing constant viscosity and the absence of surface or dimensional defects.
- The GRP-H solid state relay, compact and with integrated heatsink, ensures precise control of current up to 120 A. IO-Link communication also reduces the number of I/O boards through the integrated management of commands, alarms and absorbed current.
The solution is scalable and compatible with PIDs integrated into PLCs or remote modules. Recipe storage and historical trend functions support rapid production changes and continuous quality improvement.
Requirement:
Control of the moulding process
The injection moulding process requires the correct balance between the quality, objective and speed to be derived from the material used for moulding and the design of the item to be moulded. The process control must take these characteristics into account to move the different electric or hydraulic drives while managing complex recipes. In addition, the PLC must be able to support rapid changes in materials, offer integrated diagnostics and provide a rapid response in the event of deviations.
Solution:
G-Mation is the platform for the complete, synchronous and integrated control of the injection moulding process. The heart of the system is the G-Mation P6 CPU, supported by G3 remote modules with EtherCAT bus communication. Integrated PID algorithm manage thermal control and also the drives, with no external gateways required. The user interface is managed through an integrated webserver and displayed using the G-Mation W55 browser panels, which allow the projection of customisable dashboards.
Main features of the Platform:
- Pre-configured and customisable application templates
- Docker technology for the installation of applications such as IoT dashboards, predictive maintenance or integration with MES and ERP systems
- Open architecture that is ready for edge computing
Requirement:
Injection force
In electric injection moulding machines, the absence of the hydraulic circuit makes it impossible to monitor injection force in the traditional way (by measuring oil pressure). For this reason, it is necessary to adopt alternative solutions that can provide the same data with high precision. Injection force is the most critical parameter of the process: the filling quality of the mould, the absence of aesthetic defects and the dimensional consistency of the product depend on injection force control. The measurement must therefore be extremely accurate and taken as close as possible to the injection screw, so as to detect changes in load in real time.
Solution:
The DLC diaphragm load cell was developed by Gefran for fully electric injection moulding machines:
- Its flat structure allows it to be directly integrated into the injection unit without increasing the overall length of the machine.
- It is available in amplified or unamplified version, to adapt to different control configurations.
- Interfacing with the PLC allows precise control of the injection motors, optimising speed and pressure profiles.
Requirement:
Measurement of injection pressure at the nozzle
Adjusting the injection force in electric machines is one of the main critical issues, since in the absence of the hydraulic circuit, there is the risk of applying incorrect forces, which can damage the mould if excessive, or lead to incomplete filling if insufficient. A single diaphragm load cell installed behind the screw is not always enough, especially when starting the machine or changing the mould. To ensure reliable control, it is essential to directly measure the pressure near the nozzle, so as to accurately calibrate the injection profiles and ensure the repeatability of the process.
Solution:
The IN-4000 sensor measures the injection pressure directly at the nozzle of the moulding machine:
- It allows initial calibration of the injection force, improving the accuracy of subsequent cycles.
- It is particularly suitable in ISO 9000 certified processes, where repeatability and the traceability of parameters are fundamental.
- The sensor is mounted magnetically via a nozzle adapter, which protects the sensor from mechanical damage.
- A heating band keeps the sensor up to 230°C, preventing solidification of the melt in the measuring chamber and allowing multi-shot tests with different pressure levels.
Requirement:
Tie bar deformation
Calibration of the mould closing force alone is not always sufficient to guarantee the quality of the process. In many cases, the tie bars are not tensioned evenly, which results in the applied force being concentrated on one of the four corners of the platen. This imbalance generates an inhomogeneous injection that can produce burrs and aesthetic defects, and over time lead to wear or breakage of the tie bars themselves.
Solution:
Gefran proposes two approaches to monitor tie bar deformation:
- Continuous monitoring: “lance” sensors, such as the ML1018 models, installed in special holes in the tie bars, detect deformation in each closing cycle. It is possible in this way to obtain detailed trends and promptly intervene on the process.
- Mould change monitoring: QE2008 magnetic sensors, which can be positioned directly on the tie bars, allow quick checks during the test cycles at each format change, without the need for permanent installation.
Requirement:
Deformation of the moving platen
The force required to open and close the mould is cyclically applied to the moving platen; an imbalance of the force applied during closing can cause defects in the finished item, mechanical stress on the structures or premature failures. The accurate monitoring of the deformation of the platen pushed by the hydraulic force enables prompt intervention in the event of any imbalances, maintaining high product quality and improving the durability of both the machine and the mould.
The Gefran SL strain sensor is an ideal solution for closing force monitoring because it is so easy to install, it is mounted directly on the back of the moving platen, with no complex operations needed. It is available in SL-VAA and SL76-VDA versions, with integrated amplifier and respective analogue or digital output, providing for easy integration into existing control systems.
Designed for industrial applications characterised by very fast cycle times, the SL sensor guarantees reliability and precision even in harsh conditions.
- Mechanical deformation amplification between the two installation areas, with stable and repeatable signal.
- Optimal in voltage mode, for accurate and responsive monitoring.
- Robust stainless steel structure with IP54 protection rating, resistant to shocks, vibrations and contaminants typical of the production environment.
Requirement:
Enhancing Production Data
Solution:
IoT platform and Generative AI: Max and GAIA
Operating Principle
The movements of the injection machines with electric drive (closing, injection, ejection and movement of the unit) are driven by a brushless electric motor with screw transmission. Mechanical energy is supplied on demand, eliminating the constant consumption typical of hydraulic machines that need to constantly maintain pressure in the circuit. The machine is controlled through encoders that guarantee extremely precise and repeatable movements. The injector doses the molten material and introduces it into the mould with programmable speed profiles: it starts with a fast push to fill the cavity, and then slows down near the setpoint, so as to reduce internal tensions and ensure surface quality. Mould closing is also controlled, with modulated speed to approach safely and with electronically adjusted clamping force. This architecture eliminates hydraulic fluids, reducing noise, vibration and heat loss.
Requirements and Technology
The control systems required by electric machines differ from the controls used in traditional hydraulic machines. The main requirements are:
- The position of the motor is adjusted via an encoder; therefore, there is no need for position sensors. However, the feedback of the force that is applied is not easily obtainable, as there is no hydraulic pressure. Special diaphragm wireless load cells, mounted between the motor and the injector, are used to monitor the motor’s thrust.
- Cylinder and mould temperature management, made more critical by the absence of an oil circuit that can act as a heatsink. Gefran PID controllers, GRP-H solid state relays and thermocouples allow fine control, essential for high-precision production.
Overall, the absence of oil is a significant advantage in terms of cleanliness, but it makes mechanical movements less controllable. The closing unit is also usually equipped with a greater number of deformation sensors than a hydraulic mould, to prevent breakage. These solutions allow electric machines to maximise productivity and energy efficiency, guaranteeing quality and repeatability in the most demanding sectors.
Gefran offers a complete range of control platforms, pressure and position sensors and modular solutions that can be easily integrated into any plant, to ensure efficiency, safety and constant quality for the injection moulding process of plastic or rubber products.
