How Does Inclined Screw Conveyor Work?

Screw Conveyors can be operated with the flow of material inclined upward. When space allows, this is a very economical method of elevating and conveying. It is important to understand, however, that as the angle of inclination increases, the allowable capacity of a given unit rapidly decreases.

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A standard Screw Conveyor inclined 15° upward will carry 75% of its rated horizontal capacity. At an inclination of 25°, a standard conveyor may only handle 50% of its horizontal capacity. These are estimated figures and will vary with the characteristic of the material being handled. Inclined Screw Conveyor capacities can be increased over short distances, if no intermediate hangers are required.

Other aids in conveying on an incline are the use of shorter than standard pitch and/or tubular housings or shrouded conveyor trough covers. Very often it becomes necessary to use high speed to overcome the tendency of material to fall back.

The above aids are resorted to in order to overcome the tendency of a screw conveyor to become less efficient as the angle of incline increases. Vertical conveying by Screw Conveyor, on the other hand, is quite successful and it remains that a 45° incline or angles approaching this figure, are the most difficult on which to achieve successful conveying.

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Additional power is needed to convey on an incline. This added power is a function of the power required to lift the material. Judgment and experience in the art of conveying are required.

Products can be conveyed and elevated at the same time by mounting a screw conveyor at an incline. This is often desirable because it covers two operations with one piece of equipment therefore saving space and reducing downtime, maintenance cost, etc.

A standard screw conveyor will often operate normally at angles up to 15º with only a small loss in capacity. Beyond that, adjustments and/or modifications are typically necessary. The design is a bit involved and these items should be taken into consideration:

• More horsepower is required for Inclined Screw Conveyors: This is due to both lifting the product and &#;reconveying&#; product that falls back.
• Hangers should be eliminated: They create a &#;dead flow&#; area that is emphasized with inclined conveyors. This often results in the use of longer screws which require their own design considerations.