Inline colour measurement automates plastics production
However, the colorCONTROL ACS7000 inline colour measurement system from Micro-Epsilon can inspect the colour of the injection-moulded parts as they are extracted from the mould and not just after cooling down. The described method saves time and allows for a 100% colour quality control.
As soon as parts from different manu-facturers made from different materials are combined into assemblies, the safe adherence of required colour values becomes an essential quality assurance issue. In order to provide a 100 per cent control of the exact product colour shade during the plastics injection moulding, the SKZ (Süddeutsche Kunststoff-Zentrum) has developed and tested a method as part of a study for different surfaces. The system uses an empirically determined correlation of the colour between warm and cold pieces (thermochromism behaviour). Even with a temperature difference of just 20°C, colour deviations of more than 2 ΔE units can occur depending on the colouring. 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 room temperature.
The cooling curves pre-determined and stored in the software allow the colour values determined during the de-moulding process to be converted into a reference temperature (20°C). The colour is now automatically checked earlier in the process, which optimises productivity and output compared to conventional sample checks.