Modules for High Efficiency
Sumitomo (SHI) Demag
Sumitomo (SHI) Demag Plastics Machinery GmbH, Schwaig, Germany, is further enhancing the production efficiency of its machines with machine and process technology extensions. To reduce the rejects for color exchange and shorten the process overall, the German-Japanese injection molding machine manufacturer offers the activeColourChange liquid color dosing system. The system doses the liquid colorant directly into the melt-filled metering zone of the plastication unit. The upstream feed zone and compression zone thus remain free of color – therefore only a very much shorter screw length needs to be purged for color exchange. To ensure homogeneous color distribution, the screw is equipped with a special mixing zone. The user thus obtains high opacity even with low amounts of color.
To further increase both the part quality and the production efficiency, Sumitomo (SHI) Demag presents a range of technology modules. One of these modules is the activeLock switchable non-return valve. It closes the melt channels before injection by means of a short, precise rotation against the plastication direction, and thereby ensures that a small residual melt cushion, which is constant from cycle to cycle, remains in front of the screw. This leads to high process constancy, which is favorable for the part quality, particularly in the case of precision parts.
Where multicavity molds are used, the activeFlowBalance function can be used to actively stop the screw for a defined time at the transition from injection pressure to holding pressure to allow the melt pressure to equalize. This results in a balancing of the internal pressures, the filling levels and thus the part properties in the various cavities (Fig.). As a result, the part quality is improved and the reject quota minimized.
The surface quality of visible polymer parts is a critical factor in many industries. These requirements can be met with the use of the gas external pressure process (GAD) in alternately temperature-controlled molds. In the GAD process, which Sumitomo (SHI) Demag is implementing in cooperation with Stieler Kunststoff Service GmbH, Goslar, Germany, gaseous nitrogen exerts an areal pressure on the non-visible side of the part after injection into the cavity. The melt is thereby pressed against the forming structure of the mold at the visible side, making the reproduction much more accurate. Since the gas maintains the holding pressure throughout the entire cooling time, low-stress, low-warpage parts are produced. This process combination is demonstrated with the manufacture of a radio panel on an IntElect 50 all-electric injection molding machine with 500 kN clamping force.
Fakuma Hall B1, booth 1105
Sumitomo (SHI) Demag Plastics Machinery GmbH
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