Screw feeder designProper feeding through well designed pitch increase
A screw feeder is a screw that is mounted directly under the opening of a hopper. The product in the silo therefore rests on a part of the screw, and the screw flights are filled completely. This is a clear difference with a transport screw or screw conveyor, where the product is fed with a capacity that is smaller than the capacity of the screw.
A screw feeder is used a lot for the feeding of powders from a (wedge shaped) hopper. The reasons for this are:
* an even withdrawal of the powder is well possible, resulting in mass flow.
* the screw is closed, so there is no risk of pollution of the powder or surroundings.
* proper feeding is possible, in a broad range of capacity.
* the life of the screw; a wear resistant type is possible.
* the screw can be made well resistant against for example high temperature,
aggressive environment, etc.
In a screw transport depends on the friction between product and 1) screw blade, 2) trough