Plastics production and processing

With blown film extrusion, non-contact temperature measurement is a difficult measurement task. Ambient radiation also penetrates thin films and distorts the intrinsic radiation of the films. The infrared CT-P3 and CT-P7 pyrometers only detect the infrared radiation emitted by the plastic films and ignore the penetrated ambient radiation. This is how high precision detection of the surface temperature is possible.

Foreign bodies, uneven distribution of the adhesive or unevenness when closing may produce open joints between the top material and the sidebars. The scanCONTROL laser profile sensors check if there are open joints and detect their gap size.

The thicknessCONTROL measurement system is used for thickness measurement of plates and strip materials. Depending on the measurement task and materials, the head is equipped with different sensors that measure in a fixed track or in a traversing method. Comprehensive software packages and interfaces enable measured values to be recorded.

In its sensor housing, the combiSENSOR combines an eddy current displacement sensor and a capacitive displacement sensor. This unique sensor concept enables one-sided thickness measurement of electrically non-conductive materials on metallic objects. Its field of application is the thickness measurement of plastic film or of plastic coating on metal plates. Connected to the sensor via a cable, the controller processes and calculates the signals in order to put them out via interfaces.

moldCONTROL is a thermography solution for recognising quality fluctuations in injection molding production. The compact, industrial thermal imaging camera captures a thermal image of the component directly after the injection molding process. The software compares the infrared images associated with the component (actual) to stored references (target). The identified temperature differences provide the basis for a good/bad decision reported back to the handling system.

Depending on the respective measurement task, it is sensible to carry out a two-sided thickness measurement. Arranged opposite the material, two displacement sensors detect the thickness. This measurement arrangement is particularly suitable for high speed measurements and fluttering materials. Micro-Epsilon also offers sensors and turnkey systems for two-sided thickness measurements.

In the extrusion of high quality plastic profiles, adherence to tight manufacturing tolerances is crucial. For quality assurance, laser profile scanners from Micro-Epsilon are used. Thanks to the surface compensation, the scanners reliably detect the profiles of black rubber surfaces. For gap measurement, special software packages are available with which different parameters can be easily selected.

Surfaces play an important role in the functionality and aesthetics of plastic components. Therefore, optical surface inspection is a central approach for 100% quality control. Deflectometer-based inspection systems from Micro-Epsilon inspect shiny surfaces and detect even the smallest of deviations. The defects found are evaluated and displayed in the 3D model.

As well as colour fluctuations, streaks can occur during production. With translucent films, the film colour is measured very accurately and quickly using the ACS7000 colour measuring system together with the ACS3 transmission sensor.

In order to avoid defective production and to conserve resources during the extrusion of plastic products, it is crucial to recognise colour deviations not just at the end of the process chain but already during the ongoing process. The accurate colourSENSOR CFO colour sensors are used for colour recognition in the process and transmit colour deviations directly to the control system.

In plastic injection moulding, the exact colour shade of the products is important, as the colour changes during cooling. To date, it has only been possible to measure random samples of cooled pieces. However, the colorCONTROL ACS inline colour measurement system from Micro-Epsilon can 100% inspect the products as they are extracted from the mould.

In film production inline thickness measurement guarantees constant product quality. Micro-Epsilon's KS5 combination sensor measures the thickness of films in a non-contact and thus wear free process.

Thickness measurement using displacement sensors is a wide application area. Basically there are distinctions between non-destructive/destructive, non-contact/with contact and one-side/two-sided thickness measurement. The Micro-Epsilon measuring techniques for thickness measurement are all emission-free whereby no emissions regulations of any kind have to be complied with. Thickness measurements must be performed both with contacting as well as with non-contact sensors whereby non-contact measuring techniques show advantages as regards accuracy and measuring speed. There is also a distinction between one-sided and two-sided thickness measurement. Two-sided thickness measurements are carried out with at least one pair of sensors which are installed together on one axis. This pair of sensors measures the target synchronously. The difference between the measurement results (C-A-B) produces the thickness of the measuring object. One-sided thickness measurements must only be performed with non-contact sensors. In doing so, the target is only measured with one sensor and either only a part of the target thickness (e.g. layer thickness) or the complete measuring object thickness is measured. Thickness measurements are mainly used in process control and quality assurance, e.g. for the control of extrusion systems or 100% checking of tube diameters.

The thickness of blown films is an important aspect in terms of constant quality in blown film production. Partially strong thickness tolerances can occur for the production in doing so. The blown film system from Micro-Epsilon measures the profile of the film with or without contact directly after the extrusion nozzle. Located on a reversing frame, the system continuously traverses the film tube and provides the data to the host system for controlling the extrusion nozzle.