Hopper Machines

Hoppers come in many sizes and configurations. They are typically used on the packaging line to store components and in processing to store dry bulk materials though the term is occasionally used to refer to liquid tanks. In most applications, they act as a reservoir or buffer to keep materials flowing smoothly to the machine or process without the need for an operator in constant attendance.

Hoppers may be mounted in a fixed location, for example to meter resin pellets into a plastic molding machine or caps into a capping machine hopper. They may be portable either mounted on castors or designed to be handled by finger lifts and fork trucks.

Typically they are filled from the top and emptied from the bottom. Some hoppers are designed to be dumped and may have no bottom outlet. These are sometimes called totes. Others may be designed to be filled and emptied from the bottom and have no top outlet.

Materials include plastic, stainless or painted steel, aluminum, copper and other metals and even wood in some cases. Sizes range from less than a cubic foot to dozens of cubic feet though at some point they become siloed.

Hopper design needs to consider material flow characteristics. If the hopper is to be dumped, as opposed to being emptied from the bottom, it needs to have an open or openable top. If it is to be used for powders, It should probably have a circular footprint and a fairly steep taper to help material flow to the outlet. Vibrators and agitators may be required to aid flow.

Valves at the bottom of the hopper must also be matched to the material. Ball or butterfly valves will work with powders and fine granulated products. When used with larger products such as pharmaceutical tablets or candies, they will crush or shear the product. For these types of products slide gate or iris valve should be used.

Another consideration for valves is whether they will be used fully open-closed for dumping or partially opened to control flow rates.

Hoppers are more than dumb boxes. Properly designed they enhance process efficiency. Improperly designed, they can be a hindrance rather than a help.