ServTek: Superior Colour Mixing
ServTek has launched the MeltStar screw, which has clear advantages in crucial areas of colour mixing such as colour ratio, streak/swirl elimination, and visible surface colour. MeltStar is reported to be the only screw found to eliminate streaking, swirling, and core removal marks at a 1% colour ratio. This brings obvious benefits such as lower scrap rates, reduced cycle times, and overall cost-savings. MeltStar is a design innovation based on certain barrier screw features. The undercut barrier flight separates solids from the melt. The melt channel cross- section continually increases downchannel to minimise shear and work input to the melted particles that flow over the
barrier flight. The solid channel cross section continually decreases downchannel to maintain compression and work input to the unmelted particles. By removing the melted material from the working compression channel, unmelted pellets are continually presented to the barrel surface,
maximising the melting capacity of the screw. Barrier melting capacity is combined with a spiral mixing head to provide melt homogeneity and colour mixing. The multiple spiral channels split the material flow in the vertical plane, and the V-cuts in the outer diameter split the flow in the horizontal plane.