EN 
简体中文For maintenance and engineering departments in extrusion and injection molding, feed screw and barrel wear is a serious problem, and rightfully so. Excessive wear on the plasticizing unit can cause a serious set of performance issues that naturally impact cost and overall quality. The need for baseline data and wear monitoring procedures to avoid excessive loss of productivity.
Feed screw wear in extrusion and injection molding is similar, with the majority of wear occurring in the high pressure region, especially in the transition section and the last few metering turns. Differential pressure is required to generate the force that deflects the screw, not the usual high pressure. Metal-to-metal contact can occur, but this is a result of mechanical conditions. Wear testing in many industries has shown that increased pressure and temperature lead to increased friction.
Mixing sections and baffles are also prone to wear because their function requires resin to flow through their geometry. Dispersion mix designs incorporate some form of undercut geometry that applies high shear forces on the resin to promote a more isothermal melt and uniform color. Sufficient dispersibility is lost as the hybrid design wears out. Much like the dispersive mixing design, the barrier is undercut to help separate the molten pool from the solids bed. Barrier designs may lose their melting ability and efficiency as undercut threads wear.
Screw wear is usually a slow process that can go unnoticed until performance is greatly reduced. Minor wear has little effect on overall performance as machine parameters can be adjusted to maintain productivity. Leakage flow is inevitable when the radial clearance between the screw flight and the barrel wall increases. Operators typically see reduced throughput and increased melt temperature, forcing higher rotational speeds and energy consumption to maintain the desired rate. As the radial clearance increases, the screw cannot generate the necessary pumping pressure to maintain the desired output.
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