Analysis of particle size distribution in extrusion compounds

  • Automated quality control starts as early as in the compounding stage
  • System replaces time-consuming visual checks by means of microscopes
  • Measurements in compounding lab can be linked to final quality control

Pixargus is now offering its PCR compound analyzer also for laboratory use. By inspecting the compounding quality ahead of the extrusion process, the new PCR 20/40 system ensures that only high-quality compounds will be processed.

Automated quality control starts as early as in the compounding stage

The new PCR 20/40 system automatically measures in real time the size of particles in the surface of extruded test strips processed by lab-scale extruders in the compound mixing shop. The system allows to determine, ahead of production, whether a compound will be suitable for production and whether the final product will comply with the specified quality requirements. Especially in the rubber industry, this analysis is indispensible as the input material is a natural product and its properties may vary within a broad range. During vulcanization, even just a very few minor impurities in the compound may already lead to large increases in volume and hence to a significant deterioration of quality.

System replaces time-consuming visual checks by means of microscopes

At the same time, PCR 20/40 cuts the time-consuming effort involved in the visual checks of the test strips by means of microscopes. This accelerates the overall compound testing and approval procedures prior to production.

Measurements in compounding lab can be linked to final quality control

The fact that the results from the measurements in the compounding lab can be linked with the inspections made as part of final quality control provides a very high potential for quality improvement. By relating the analysis data from the compounding process to the data acquired by the Pixargus inspection systems installed at the end of the process chain, it is possible to objectively determine which compounds will lead to products of optimum quality and which ones will result in rejects.

Also for the incoming control of materials, the system offers benefits: should a delivered compound not comply with the specified quality requirements, the laboratory may provide testing logs containing objectively determined, substantial data.

Customer testimonial: Toyoda Gosei Meteor GmbH

Christian Struck, Process Developer Continuous Vulcanization at Toyoda Gosei Meteor GmbH, where the new system is employed, says: “With the new system in place, we have been able to analyze the compound quality much faster, much more efficiently and above all based on objective data, before the production process actually starts. This has reduced the costs of the analysis process by approximately 30 percent, while achieving an improvement in quality. The system has paid back within a period of six months.”

Background: The technology in detail

While the original PCR system with its very sturdy housing designed for industrial use and the integrated air-conditioning system was specifically designed for stationary use, Pixargus has now complemented the basic system with a very compact smart version based on panel PC technology, allowing it to be easily and flexibly moved about between the various lab-scale extruders.

The usually about 1-meter-long test strips produced by a lab-scale extruder are placed on the conveyor belt of the PCR system. The conveyor transports the strips through the measuring head fitted with a special illumination unit and a high-resolution camera, which scans the surface as the strip passes through the measuring unit. PCR 20/40 captures particles from 20 µm upwards and evaluates their size distribution. Should the distribution not be as specified, PCR 20/40 will trigger an alarm and send out digital and analog I/O signals for a machine stop. The system can be used both for testing new compounding recipes and for monitoring the quality of compounds over longer periods of time.

Pixargus has derived PCR 20/40 from its ProfilControl series of surface inspection devices for rubber profiles. These devices are equipped with a special LED segment which makes the individual particles of the surface clearly visible. A high-resolution line scan camera captures images of the complete surface. The images produced by the camera are evaluated at a rate of approximately 100,000 particles per minute by a software specifically developed for this application.


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