Material Preparation
A hopper loader is a device that draws granulate by vacuum from a bag, octabin or dryer and automatically fills the hopper of the injection molding machine. A standalone loader has its own vacuum motor and feeds a single machine; in a central system, many loaders connected to a shared vacuum pump are fed from a distribution table. It eliminates manual filling, contamination and the machine running out of material.
The deciding factors in selection are hourly consumption, conveying distance and height difference. A standalone loader is economical for a few machines; as the number of machines increases, a central system comes out ahead in both energy and maintenance.
Simultaneity must be planned in a central system: if all the loaders call at the same time, the pump capacity is not enough. The symptoms of insufficient capacity are lengthening fill times, recurring alarms and the machine at the end of the line running short of material.
Up to three or four machines and over short distances a standalone loader is sufficient. With more machines, dryer integration and frequent material changes, a central system gives lower operating costs.