Two feedscrew rivals have allied their proprietary technology to tackle tough plasticating jobs such as consistent mixing of polymers and liquid colorants at high mixing rates.
Glycon Corp. (Booth S1285) brings its DM2 feed screw to the alliance and Westland Corp. (Booth N4733) contributes its Eagle mixing section, the firms announced the week prior to NPE. Each company will display the new system at their respective booths.
Glycon general sales manager John Phelan said dispersion of liquid colorants can be a problem at high mixing rates because when the colorant is added to the mix it can act as a lubricant and cause the screw to slip. More processors are using liquid colorants because they often offer significant savings over color concentrates. Glycon and Westland have begun trials for their new system and report early success in blow molding work, said Phelan from Glycon's Tecumseh, Mich., head office.
The DM2 has a dynamic mixing and melting action that produces more output than a typical barrier screw and without the shear that can degrade polymers, Glycon claims. A thermal crossover zone is positioned along the screw at a point where up to 80 percent of the polymer is melted. The unique configuration of channels and undercut flights allows melt and pellets to interact without excessive pressure buildup. The crossover is repeated several times, providing an unwinding effect so that the inner layer in one channel becomes the outer layer in the next channel. Unmelted pellets are mixed continuously with melted polymer so that thermal energy is transferred to any unmelted pellets, providing a homogeneous melt.
Wichita, Kan.-based Westland's Eagle mixing section, normally about three diameters in length, is positioned downstream from the DM2. Alternating helical barrier and wiping lands convey and mix the melt. Mixing is enhanced by two or three notches in each barrier land. The notches bottom out on the root diameter and allow some of the melt to avoid crossing the barrier lands, changing direction of the melt flow as it moves throught the mixer. The Eagle section accepts at least 95 percent of the melt that is conveyed into it without restricting flow.
Glycon designs and makes screws, barrels, shut-off valves and other melt-stream components for extrusion, blow molding and injection molding.
Westland makes barrels and screws and boasts its tool-steel-lined barrels are wear-resistant and straight.