In modern plastics production, innovative sensor technologies offer far-reaching benefits, from increased efficiency and improved product quality to more sustainable production processes. Sensors are not only tools for quality control, but also key elements for optimising the complex and often energy-intensive processes involved in plastics processing, says Glenn Wedgbrow, Business Development Manager at Micro-Epsilon UK.
Micro Epsilon UK
The implementation of modern sensor technologies enables precise monitoring and control of all stages of plastics production. From raw material supply to processing and final inspection, Micro-Epsilon sensors enable real-time acquisition and analysis of process-critical data. This leads to a significant reduction in production downtime and material usage, which not only reduces costs but also protects the environment. It also ensures consistently high product quality and significantly increases cost-effectiveness.
Efficient diameter testing of extruder bores
The idiamCONTROL sensor system has proven itself in the field of machine maintenance. It is specially designed for measuring internal diameters in extruder housings from 32 to 180 mm. The system offers unsurpassed accuracy due to measurements using capacitive displacement sensors. This technology allows wear to be precisely determined and defective segments to be specifically identified, thereby extending the service life of the machines and minimising unplanned downtimes.
For the measurement, the sensor is pushed to the end of the extruder barrel and pulled out while measuring the bore hole. The reinforced cable is attached to the sensor using a special plug. The diameter values of the staggered test cycles are saved. The measured results are then calculated and the resulting wear is determined. The diameter of the housing bore is measured on six tracks with maximum accuracy.
The results of the measurements are visualised on a compact touchscreen, which shows an immediate graphical representation of the diameter over the entire length of the bore. Tolerance deviations are visible at a glance, enabling a quick response and adjustment of the production process. The system also has a USB interface for data output and calibration monitoring to check the working status of the system.
One-sided thickness measurement using combination sensor
An important measurement task in the plastics industry is the high-precision thickness measurement of very thin films. Several sensor technologies from Micro-Epsilon are available for this purpose: confocal chromatic sensors, interferometers, as well as capacitive sensors. The combiSENSOR, which combines the capacitive measuring principle with eddy current technology, offers a unique solution.
The unique sensor concept has been specially developed for measuring the thickness of non-conductive materials that rest on metallic substrates, such as plastic films or plastic coatings on guide rollers.
During the measurement, the eddy current sensor detects the distance to the underlying metallic material, such as a roller, by penetrating the plastic layer. At the same time, the capacitive sensor detects the distance to the surface of the plastic. The thickness of the material is determined by calculating the difference between the two sensor signals, which enables extremely precise measurement.
The sensor is connected to a controller via a cable, which is controlled via a user-friendly web interface. This interface not only allows easy configuration of the sensor and controller, but also allows arithmetic operations to be performed on the acquired signals to generate optimum accuracy and functionality for specific applications.
Innovative absolute interferometer for thin films
In film production with blow moulding equipment, white light interferometry can be used to verify the correct film thickness before the blown films are collapsed. In all applications, the devices can be integrated into inline inspection systems for quality assurance. They can be used in industrial environments and perform precise measurements down to sub-micron accuracies.
The interferoMETERs from Micro-Epsilon not only provide precise thickness values, but can also be used for multi-layer thickness measurements. A decisive advantage is the distance-independent measurement, where a stable nanometer-accurate thickness value is achieved. This is how the film can move within the measuring range without influencing the accuracy. The sensors are industry-optimised with a robust metal housing and flexible cables.
Three-dimensional precision
Micro-Epsilon's 3D sensors are used for complex geometry, shape and surface inspection of plastic objects such as injection moulded parts. The surfaceCONTROL 3D 3500 is a high precision 3D snapshot sensor designed for automated inline inspection of diffuse reflective materials. The sensor uses fringe light projection for direct and precise 3D measurement. With a Z-axis repeatability of up to 0.25 µm, it sets new standards in high precision 3D measurement technology and reliably detects even the smallest deviations in flatness and height differences.
The compact sensor not only offers high measurement accuracy, but also high speed data processing. It is equipped with Gigabit Ethernet for fast data output and also supports EtherNet/IP, PROFINET and EtherCAT via the 2D/3D Gateway II. Evaluation can be carried out using the manufacturer's own 3DInspect software, which provides real 3D data, but is also compatible with GigE Vision, enabling simple integration into third-party image processing software. The sensor can therefore be used flexibly in various applications in the plastics industry.
Colour monitoring in the extruder
The colorSENSOR CFO is an advanced colour sensor controller developed for precise colour detection tasks in the plastics industry. It impresses with its high colour accuracy, modern interfaces and simple operation. CFS sensors connected via fibre optic cables enable flexible applications for various measurement scenarios. Applications for the colorSENSOR CFO include, for example, the colour inspection of interior parts, packaging and the colour sorting of closures.
The sensor generates precise measurement results even under extreme environmental conditions such as the extrusion of plastics. In this case, the material colour of the pellets is measured directly in the extruder to avoid overheating. Otherwise, this would cause burns resulting in undesirable discolouration. These measurements take place under extreme conditions – up to 200 bar pressure and temperatures of up to 250°C. In addition to their robust design, these sensors are characterised by high repeatability with an accuracy of ΔE < 0.5. This enables precise colour measurement and ensures consistent quality of the end product.
Due to these properties, the sensors make a significant contribution towards optimising process control and increasing production efficiency. The measurement results are then used for process control and quality control in order to continuously monitor the production parameters to ensure high-quality products.
Complete measuring systems for film measurement
In addition to sensors, turnkey measuring systems are also available, such as the new thicknessGAUGE, which is available in C-frame and O-frame configurations. This compact system is sturdy, powerful and delivers micrometer-accurate values for 100% inline thickness inspection. The system is equipped with an integrated linear unit with electromagnetic drive, motor control and automatic calibration device, as well as a multi-touch PC with pre-installed software.
The thickness measurement system works with either laser sensors, laser scanners, confocal chromatic sensors or the combiSENSOR, depending on the requirements of the measurement task, allowing it to be applied to a wide range of different surfaces and materials.
The thicknessGAUGE O.EC model is based on the combiSENSOR. It combines an inductive sensor based on eddy currents and a capacitive sensor and therefore measures the thickness of non-conductive materials, which are guided over a measuring roller. They are particularly suitable for reliable and precise thickness measurement of films and plastic strips. The thicknessGAUGE O.EC is also particularly robust in harsh, dirty environments with high ambient temperatures.
The system is designed as an O-frame and has a sensor unit that traverses over the belt. Due to the innovative technology, the thickness measurement is contactless from only one side. The guide roller serves as a reference target for the integrated eddy current sensor, while the integrated capacitive sensor determines the distance to the material surface. The difference between the two signals is calculated by the controller as a thickness value and output as a highly accurate measured value.