The unequalled advantage of this multi-component technique is that colour change is totally eliminated, unlike in the past when each colour change meant a production stoppage of at least two hours. Also, the costs of the expensive plastic material required when released during colour change are now saved in full.
Toothbrushes being injected one after the other - which is the usual procedure - also causes longer lead and delivery times and the need for the toothbrushes to be put into intermediate storage.
Complex multi-component moulds: the cost-effective solution for making identical products with different colours
Building a 7-component mould was a major technical challenge both for the mould and toolmaker, considering that 7 injection units had to be connected to the mould in the tightest of spaces. The availability of several material feeds, the different processing temperatures of the various materials and the close spacing between the different nozzles at the same cavity were also factors which had to be taken into account. Injection molding was done on a 6-component machine from Engel. The 7th injection unit from Boy was integrated additionally in the production process.
Mold-Masters supplied the best hot runner technology for this complex application, with the advantages of this hot runner system being the special two-part soldered runner which is unique for Mold-Masters. Instead of having only straight channels, these runners have as many as three melt levels with gentle curves and turns. This means absolute design freedom owing to natural balancing, a uniform thermal profile and a comparatively low construction height. This technology allows two or more melt flow-ways to be integrated into a single runner. The design also allows six and more materials and colours in a single runner.
In general, these complex multi-component moulds are the most cost-effective solution where identical products are to be made in different colours.