How to get a uniform and accurate color dispersion with intrusion molding?

Choosing an injection molding machine can be a challenging task, as in many cases the machine is used to manufacture many different parts. Therefore all the requirements should be considered while taking into account of course the financial expenditure. We will have to compromise on some of the parameters. The result of such a compromise could be a machine with a slightly smaller maximum injection capacity than the product we want to produce.

Combining injection molding and extrusion

A technique for dealing with this situation is Intrusion Molding, which seems like a combination of injection molding and extrusion. This technique involves three stages: (1) partial filling of the mold by continuous rotation of the screw, as in extrusion, (2) a plasticization stage in which the screw moves backward similar to a standard injection process, (3) a standard injection stage, in which the mold is fully filled.

Schematic illustration of the stages of the intrusion process

Schematic illustration of the stages of the intrusion process

Using ColorSave 1000 for intrusion molding

In the latest software update of the ColorSave 1000, one of the innovations is the support for the intrusion process. ColorSave 1000 operates according to signals coming from the production machine. According to the signals, and other parameters, the color feeding rate is ​​calculated. While in standard injection molding processing two signals are sent – a signal at the plasticization stage and a signal at the injection stage, in intrusion molding processing three signals are sent. A signal at the at the beginning of the process, when the screw begins to rotate similar to its activity during extrusion, a signal for the plasticization stage, and an injection signal for the third stage of the cycle. When in intrusion molding mode ColorSave 1000 learns the length of the signals, and calculates the desired motor speed so that the required amount of material is fed to the injection machine during the cycle. Because the feeding screw is relatively small for the injected part, ColorSave 1000 feeds a small portion of the masterbatch even at the relatively short injection stage.

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