In reference to their color, synthetic pellets ought to be within a close range of tolerance with a color standard. Furthermore, color deviation occurring during production should be correctable by changes of process parameters or by compensation during a later mixing of the batches. However, in all cases the color deviations have to be discovered early in order to prevent a production of waste products. Color deviations of the plastic pellets can usually be correlated to the extruded plaque. Now the synthetic pallets can be directly measured and the time-consuming production of extruded plaques can be avoided.

Mode of operation

The systems are usually installed above the separation sieve behind the granulator. The system continually measures color and immediately reports color differences to the machine operator. The operator can then vary the process parameter in order to approach the set point of the color. Vice versa a change in color could indicate early process variations and allow for corrections. During color change or during the start of production the system can be applied to shorten the color change, shut-down and start-up times. The system reports exactly when the color of a batch runs out of the tolerance level and reject production commences. At the system start it is clearly recognizable at what point the color of the product is within specifications and can be shipped. In connection with a host system the execution of measuring job and the transmission of measuring results takes place fully automatically. Frequently test certificates are required in order to show proof of the quality of a batch. The test certificates show diagrams which depict the deviations of the color in reference to the standards and the evenness of the color during the production process. Furthermore, the results can contain indications whether or not the batches can work together or how they have to be blended.