Drawback narrow channels

A further drawback of this construction is that it is not convenient to have a taper outlet slot on a container so the practice is to slope the feeder casing from the screw diameter to a parallel hopper outlet size that matches the largest diameter of the screw. All most invariably, this results in a casing wall inclination at the smaller end of the feeder that is inadequate for product slip. In combination with the gap at the side of the screw to the casing wall that fills with static product and opposes wall, the effect is to create a narrow flow channel with non-mass flow characteristics. The economics of manufacture also detract from widespread adoption of this technique as both the screw and the casing have taper components that demand extra fabrication time. 

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