In traditional injection molding, shear heat develops due to dragging resistance of the resin between the screw flights and the barrel. This causes fluctuation of the molten resin density and various other problems. The SL (Spiral Logic) screw assembly avoids these problems by eliminating shear heating instability.
Benefits of the SL screw assembly include:
- A Uni-Layer Melting Model that eliminates the compression zone of the screw and prevents burn spots and stagnation of the melt in the barrel
- Improved resin pressure stability and elimination of random short shots
- Significantly decreased screw and barrel wear caused by the formation of super critical water
- Elimination of product surface blistering due to incomplete material melting
The SL screw assembly also allows exceptionally fast color and/or resin change-out. In the two-cavity mold example shown here, the 40th shot shows complete changeover from black to white.
The SL screw assembly is selectable as a standard option on Sumitomo (SHI) Demag’s SEEV-A Series advanced all-electric injection molding machines and as an option on the SR-Z vertical and SE-DUZ direct-drive all-electrics for parts sized from fractional grams up to 244 grams (8.7 oz).
Use this link to view a technical presentation and injection molding demos:
SL Screw Assembly videos