The 3 phase screw is a screw for injection molding based on a principle of a single flighted area (with a variable pitch and conical core) ending into two dynamic mixers at the front: the first one is a barrier and the second one a pineapple mixer. The combination of the two mixers increases both the shear stresses and make the plasticizing process faster and more effective. In many cases it will reduce the amount of masterbatch use. It is not suitable for all polymers. It’s increased use is mainly in the packaging sector. The 3 phase screw geometry contains two dynamic mixers for specific use:

BARRIER MIXER

This first mixer has a length of 3 to 4 times the screw diameter and is in principle a barrier design; two channels (or multiple variants 2-4), separated by a barrier flight, allows separation of the molten polymer. In the first channel, containing the solid mass, volume decreases as the granulate is downstream  transported along the screw while the second channel containing the molten increases its volume to accommodate more molten material.

PINEAPPLE MIXER

3-phase-2The second mixer, more downstream than the barrier, is composed of a few rows of teeth (usually from 3 to 6) to increase the homogeneity of the melt and to avoid enclosures.The screw has been developed to reduce the plasticizing time in injection molding. The main use is in the packaging sector. The screw has a better homogenization of the melt compared to screws with a traditional profile and therefore reduces masterbatch.

The mixers of the 3 phase screw will increase the friction and therefore, compared to other screws profiles, increase the temperature of the molten polymer to accelerating the melting of the polymer. The screw is therefore not suitable for the plasticizing of the polymers that are sensitive to overheating like POM, PC, PMMA, PVC.

The company MAXI MELT has the technology to develop screws with 3 phase profiles to optimize your plasticizing processes. Depending on the type of polymer to be processed and the molded part we offer the optimal solution.