Auger Machines

Auger fillers are versatile volumetric fillers capable of filling a variety of dry products. Products filled range from fine powders such as a talc or flour, through granular products such as sugar to larger piece products such as corn, birdseed or even small candies. Some auger fillers can be used for handling viscous semi-liquids like grease.

The augur filler consists of a conical hopper-reservoir which tapers to a smaller discharge tube. An auger or screw is mounted in the center of the hopper and is rotated to drive product down and out the discharge.

The amount of product to be dispensed is determined by the size of the auger, its speed and the number of rotations it makes. Augur size is matched to the hopper. Dispensing by augur revolutions is more or less linear. That is, if 1.5 complete revolutions dispense 1 ounce of product, 3 should dispense 2 ounces of product. Speed can also affect dispensing.

The auger is driven by a motor mounted on the top of the machine. A controller allows the amount of rotation to be precisely controlled. Older systems may continuously run motors with a clutch/brake to control auger rotation. Newer systems will usually have direct drive servo motors with touch screens.

Some products may not need a discharge valve. Most will need something more positive. The conceptual sketch above shows a “birdfeeder” tray on the discharge. This tray prevents flow when the auger is not turning.

Other systems may use a butterfly, slide or other types of valves for more positive shutoff.

A key issue in any powder feeder maintaining a consistent flow. This is especially true when the powder is funneled from the larger diameter of the hopper to the discharge. Ratholing, sometimes called bridging or arching is one common problem.

Ratholing occurs when only some of the powder flows, creating a void. The augur continues to turn, but because of the void, less, or even no, product is fed.

This affects filling accuracy. Generally the finer the particle size, the more prone it will be to ratholing. Some products like brown sugar may have relatively large particle sizes but, because of a tendency to clump, may have problems with ratholing.

Ratholing can sometimes be solved by mounting vibrators on the side of the hopper to help flow. An agitator, mounted to the auger as shown in the sketch, can be used to keep the product stirred up.

This may cure the ratholing but excessive mixing by the agitator can damage or cause demixing of some products.
Some sticky products may have a tendency to stick to the hopper walls. If needed, a scraper can be used instead of or in addition to the agitator to continuously scrape the walls.

Safety must always be paramount and sometimes we don’t realize how flammable or even explosive some common products like sugar or flour can be. When selecting any machinery, care must always be taken to address any potential safety issues.