Knowledge Hub
03/05/2019
Coloured Injection Mouldings
When injection moulding plastic parts for our customers most of them tend to be black or natural, but there is a wide range of colours available. If a specific colour or shade is needed we can generally match to a RAL and Pantone references or we can colour match from existing products or samples. There are many different options available depending on your requirements.
When manufacturing coloured injection mouldings, there are two common ways of adding colour to polymers; adding masterbatch or having the material compounded. Below we have summarised the advantages and disadvantages of both colouring options.
Masterbatch
Masterbatch is a solid concentrate of colour and is supplied in granular form as pellets which are similar in size to most polymers.
There are two different types available, universal or polymer specific.
Universal is compatible with a broad range of polymers and polymer specific is produced using the same base polymer as the plastic being coloured, for example nylon or ABS.
When complex or engineering polymers are being used this tends to determine that polymer specific is needed to ensure the masterbatch properties match polymer properties, especially when high temperature materials or materials with complex chemical structures are being used.
Masterbatch granules are mixed with polymer granules at a pre-determined ratio, this can be anything from 1-10%. Once the granules are thoroughly mixed they are loaded into the
injection moulding machine for processing. This offers an easy and convenient way of adding a colour to polymer to create coloured injection moulded plastic components.
Advantages: low cost, optimum dispersion of pigments, flexibility, quick lead times, small batches available.
Disadvantages: colour consistency throughout batch, accurate dosing is essential.
Compounding
When colour compounding, the material supplier mixes the colour with the base material during manufacture and delivers the plastic granules ready coloured. This method results in consistent, repeatable colouring and is sometimes the best option for colouring materials with a dense base colour such as fire retardant ABS.
The process is more suited to large volumes of plastic as it can be expensive for smaller quantities and the price varies depending upon the polymer being compounded. Prices are available upon request of quotation for your injection moulding project.
Advantages: excellent colour distribution, ease of use, consistent colour within batch.
Disadvantages: more expensive, longer lead time, generally larger batches or MOQ’s
