Processors who are considering Continuous Gravimetric systems, typically review three basic designs that are most common to the market. A gravimetric multi-component continuous loss-in-weight feeding system, batch type multi-component gravimetric loss-in-weight system, a single component gravimetric loss-in-weight feeder. These gravimetric systems can be designed to fit into a number of applications & industries.
When feeding pelletized or granulate materials that are free flowing, a single screw or disk feeders are typically used, and are arranged for quick change outs. When feeding powdered material we have to look at changing the material flow concepts as compared to feeding pelletized material. Feeding powder, agitation is a necessary part of the process to ensure proper flow of material to the screws. This regularly applies to fairly free flowing to non-free flowing material. Agitation typically is within the weighing hopper and refill equipment.
A question most processors ask is, “if creating agitation within a weighing process how does this affect our loss-in-weight measurements”? It is effected and it can create vibrations. Load cell technology has changed to compensate for this variable. With new software & hardware designs most load cells are able to be used with external flow aids.
When feeding powdered material, we have to look at changing the screw design concepts as compared to feeding pellets. In powders, the adaptation of twin screw feeding designs are a necessary part of the process to ensure proper flow of material for accuracy and low throughput feeding.
When feeding powdered material we have to look at changing the weigh hopper design, as compared to hoppers weighing pellets. In powder, weighing hoppers need to be non restrictive to ensure material flow. This means no cone-shaped weighing hoppers are applied unless material is free flowing. To eliminate the material flow problems the feeder is designed similar to a bowl with a wide inlet. These designs eliminate bridging and ensures an even flow of material with or without agitation.
The 2 most popular basic gravimetric loss-in-weight multi-component feeding designs in the marketplace today are; Systems that feeders on a 45 deg. angle to the material hopper, auguring the material up and dropping into a weighing hopper or level housing. Systems that feed on a 90 deg. angle to the material hopper feeding directly into a weigh hopper or level housing or directly into the process. When feeding powdered material the 45 deg. feeding system is typically not used, because the material has to be fed in an upward direction. When feeding poor flowing material, clogging and material build-up may occur. The weighing hoppers used in this type of system typically are designed with a cone shaped. Orbetron takes advantage of the feeding system that feeds at a 90 degrees, with a wide opening to the feed screw. This design will give our customers the advantage to feed both powder based materials and pellet/granular material.
Processors who are considering a multi-component gravimetric system for powder/pellet applications can use them as an online system or an offline system. When considering online systems they can be set-up to run as a starve feeder for twin screw extrusion, or as a plug flow system incorporating level control for a single screw extruder. Off-line gravimetric systems still use the loss-in-weight concept but will consider the amount of material being fed as a level base or weight base. ex. filling Gaylord’s, filling mixers, etc.
Orbetron’s S2 controller are incorporated into the feeding system and is Industrial based PC’s, Controllers now incorporate touch screen, and stand alone mouse, keyboard, &VGA monitors.
Processors that need to feed liquid additives can incorporate Orbetron’s liquid feeding technology as a gravimetric function. The liquid additive container and pump are weighed and controlled along with the other powdered/pellet materials. This can be done as an off-line or on-line process
To learn more about Orbetron and our feeding technology please contact us at sales@orbetron.com or fill out of the form below.