Not only can the colorCONTROL ACS7000 colour measurement system from Micro-Epsilon measure at high speed in process, it can also inspect the colour of injection-moulded parts as they are extracted from the mould, without waiting for the parts to cool down. This dramatically reduces cycle times and allows for 100% colour quality control.
When parts supplied from different manufacturers and made from different materials are combined, it is essential that the colour values of these parts are exact, otherwise quality assurance can become an issue. In order to provide 100% control of the exact product colour shade during injection moulding of plastic parts, the SKZ (Süddeutsche Kunststoff-Zentrum) has developed and tested a method to correlate the difference in colour of an object at different temperatures (thermochromism behaviour). Even with a temperature difference of just 20°C, colour deviations of more than 2 ΔE units can occur depending on the colour monitored. Colour measurements carried out with colorCONTROL ACS7000 and temperature measurements using the infrared thermoMETER CT sensor, generate a master curve at several different temperature levels that describes the thermochromic behaviour of the coloured polymer. This allows colour values determined on a warm component to be converted to the actual room temperature colour values.
The pre calculated ‘cooling curves’ stored in the system software allow the colour values determined during the de-moulding process to be converted into a reference temperature (@20°C). This enables the colour to now be automatically checked earlier in the process, which reduces cycle time and optimises productivity and output, compared to conventional sample checks.