Meaning
Preheating and dehumidifying polymer pellets before melt processing prevents hydrolytic degradation. The operation called hopper drying utilizes a continuous stream of dry, heated air to extract moisture from resin granules. This is essential for hygroscopic materials.
Moisture Removal
Desiccant wheels supply dry air with a low dew point to the bottom of the drying vessel. As this air rises through the material bed, it heats the pellets and carries away absorbed water. Effective hopper drying reduces the moisture content to below the critical threshold required for processing.
This action protects the polymer chains from breaking during plastification, preserving the impact strength of the moulded product.
Moulding Benefit
Eliminating water from the raw material prevents issues like splay, bubbles and brittle failures in the finished parts. When resins undergo hopper drying properly, the melt maintains its target viscosity and flows consistently through the runner system. This consistency leads to uniform shrinkage and dimensional stability across the production run.
It also reduces scrap rates during startup.
Energy Performance
Drying represents a large portion of the energy consumed in an injection moulding facility. Insulating the hopper vessels minimizes heat loss to the ambient environment and lowers utility costs. Modern systems adjust the airflow based on the production rate to avoid over-drying and wasting electricity.
This optimization ensures cost-effective production without compromising polymer properties.
