Vibratory Conveyors & Horizontal Motion Conveying

While most applications are horizontal, some are required to transport at an incline or a decline. It is possible to move products up very shallow angles using differential motion. The material/object physical characteristics will determine the practical incline. Different product shapes will convey better up inclines than others. Round or spherical product shapes tend to lose the conveying energy through rolling during the end of a product run. Product cleanout of the conveyor pan may also be an issue; however, pan cleaning devices can be introduced to help remove any remaining product pieces in the conveyor pan at the end of the production run. The product travel rate and resulting conveyor capacity will also be lower when conveying products uphill. This lower capacity may be compensated for by increasing the conveyor operating stroke or the pan width.

With cleaning and sanitation issues being of utmost importance to many processors, this question comes up a lot. The typical horizontal motion conveyor consists of a one-piece formed trough (or pan) section with suspension points spaced periodically along the conveyor pan length. This allows both the interior and exterior surfaces of the conveyor pan to be easily accessed for wipe down cleaning. There are typically no support frames or springs under the conveyor to clean, which introduces cracks and crevices that are very difficult to clean. The gliding of the product along the seamless one-piece formed conveyor pan discourages build-up of materials on the surface. The continuous sliding action on the conveyor’s surface typically scours the pan clean so there’s less time required between production cycles for cleaning.

This type of conveyor can also be totally enclosed in either a rectangular or tubular shape and can be equipped with a CIP (clean-in-place) system. This type of unit employs CIP nozzles located along the length of the conveyor tube so the processor can wet-wash the conveyor interior between product runs.

Yes. Very large or heavy loads can be discharged this way in a properly designed system. The horizontal motion conveyor has tremendous load carrying ability, with some units able to convey two to three times their own empty weight.

And because it is not a “tuned” system, the horizontal motion conveyor can be operated at variable speeds for control of the material travel rate. These conveyors are not “de-tuned” by typical increases in material loading on the pan of the conveyor.

When arranged with a full hopper, the conveyor will vary its discharge rate according to the motor speed. The ability of the differential motion conveyor to convey deep product bed loads allows it to be used as a self-discharging storage unit.

The differential motion conveyor can also be equipped to provide for product aligning, singulating or product de-shingling. A food processor making chocolate covered pretzels had to use several line workers to manually align and de-shingle product downstream from a regular vibratory conveyor that was shingling the pretzels due to the vertical pitching motion. When a horizontal motion conveyor was installed equipped with aligning lanes and special de-shingling ramps, the processor increased productivity and reduced the required manual labor by significantly reducing the number of shingled pretzels that resulted in scrap, therefore increasing line yields and reducing labor costs.

Also, the conveyor pan discharge can be equipped with pneumatically actuated product dams or manually adjustable flow baffles to accumulate and meter product to other downstream equipment. Product degradation is not an issue when using product dams or flow baffles because of the gentle horizontal conveying motion which allows products like snack foods, breakfast cereals or hot dogs to be accumulated up to several feet deep.

A differential motion conveyor can be made to convey in either direction (but only one at a time) when configured correctly. The conveying direction can be reversed by reversing the drive motor’s voltage polarity through the motor’s starter. Reversing product direction can be useful in many applications, such as introducing material onto the differential conveyor’s midsection to be conveyed to a destination at one end of the conveyor and, when the conveying direction is reversed, to a destination at the conveyors opposite end. The differential motion conveyors drive can also be equipped with an optional online reversing mechanism that allows instantaneous product flow reversal for application such as filling bulk off stations.

The unique conveying action of this type of conveyor will allow the use of either mated sliding surfaces between conveyors or the use of the standard flexible boot type inlet/outlet connections. A tube type conveyor allows a sealed and separate chamber open to the upstream and downstream process. The conveying section can be a fabricated trough or enclosed tube. If you must isolate your material from your plant environment, whether it is to control dust, provide pressure isolation, blanket the material with an inert gas, or to provide other environmental controls, you can select a totally enclosed tube. One or more feed inlets can be located anywhere along the conveying sections length; each is typically sealed with a flexible boot to control dust. Cleanout ports can also be added along the length of the conveyor.

More than one inlet and discharge can be incorporated into a single conveyor. The discharges can be a preset ratio of flow, variable discharge amounts or an “all or none” to different discharges. It is also possible to create an inventory of material before each discharge for an immediate delivery during demand.

One or more discharge outlets can be located at any of the various points along the conveying section’s bottom to distribute the material. Each outlet can be fitted with a mechanical discharge gate to start and stop material discharge. These gates, typically pneumatically actuated, can be a sliding style gate, butterfly valve or tip style drop gate.

Multiple inlets can be used to introduce product from different storage devices or to meter in a mixture of materials into one conveyor. This type of conveyor will not stratify or blend these materials to ensure a uniform discharge.

Multiple lanes can also allow different products/materials to be conveyed using the same conveyor pan and a single drive unit. Products will remain separated on the conveyor. In a recent application, several sizes of the same type of products were run in the single conveyor pan.

By the same nature of gentle handling of fragile products, tough/hard or abrasive materials do not impact or wear the conveyor pan surfaces at high rates. The differential motion of the conveyor does not press the material into the pan, forcing a gouging action that will wear the pan surface faster unlike vibrating conveyors. Abrasive wear is two to four times less than a conventional vibratory conveyor.

Recently, an industrial minerals producer had an application handling abrasive construction sand. Their major concerns were dust control and downtime due to regular vibratory conveyor maintenance because of the abrasiveness of the product. A differential motion conveyor was designed with BHN 400 abrasion resistant conveying troughs, fully enclosed with integral dust covers. This conveyor showed an average surface wear of just 0.010 inches after 14 months of operation. Dust emissions were eliminated and the only maintenance required is periodic lubrication.

In another abrasive application, a ceramic parts producer had a different problem. The dust generated from a cutting process was causing their existing belt conveyor bearings to fail quickly. Access to the bearings which ran the length of the belt conveyor was difficult and cumbersome. When this belt conveyor was replaced with a differential motion conveyor, with the drive unit at one end, moving parts of the unit were not exposed to the dust loading and are now more easily serviced at normal maintenance intervals.

If the conveyed materials are corrosive in nature, like chlorinated bleach powder, a titanium conveying trough may be one solution.

If the material to be conveyed is sticky, like dishwashing detergent, a conveying trough made of ultrahigh-molecular-weight polyethylene (UHMW-PE) will prevent sticky particles from adhering to the surface. This type of conveying surface lends itself to reduced product adherence and allows expedition of the cleaning process.

Materials with a high surface tension, like raw meats or cheeses, may be conveyed using textured stainless steel conveyor pan materials.

Conveying lengths of over 200 ft and pan widths of 8-10 ft have been in use for many years. Massive impact loads and carrying capacities can be achieved with the use of structural trusses and impact beds. Pan construction of AR plate 1 inch thick and above is commonplace for the harshest conveying environments. Hundreds of these differential motion conveyors are at work today moving scrap steel. One horizontal motion conveyor, weighing in at over 350,000 pounds, 117 feet long, at almost 8 feet wide and 3 feet deep can move over 600,000 pounds per hour of scrap steel.

Water cooled conveyor pans are also used for pre-heating of the scrap metal before being introduced into the melting furnace to reduce the over-all energy requirements.

In terms of energy consumption, horizontal motion conveyors are very competitive with roller belts, natural frequency and drag type conveyors. They use less than slider belts, and substantially less than screw conveyors. The motor is sized to start the drive, and typically only experiences full load power draw when starting. For most products, the motor runs at 50% or less of rated capacity. The case of deep beds of very heavy conveyed materials, like scrap steel or castings, is the exception, where increasing material loads increase the motor’s amp draw. For most materials, the motor load is independent of the amount of product conveyed.

The differential motion conveyor is a highly adaptable piece of equipment suited well for virtually every industry. These conveyors can be operated in a wide range of extreme temperatures.

In certain applications, air or water cooling systems have been used with horizontal motion conveyors to reliably handle materials up to 1700 degrees F.

The Slipstick can be designed with several gate options: easy clean, pinch free, pivot, plug, and rail.

In horizontal, zero-pitch conveying, the translation comes from a differential or slower forward movement relative to the retraction, which is quick. The lack of vertical motion provides a much smoother and more gentle handling of the material being conveyed. When the material is not fragile or even hard and abrasive, this same motion reduces the wear on the pan.

Screening is not a good characteristic on a conveyor that does not have any vertical acceleration. With gentle handling also comes reduced little energy to dislodge nearsize pieces that get caught in the openings. Some rough scalping is possible where occasional large oversize pieces are removed from the bulk of much smaller pieces.

No. The gentle, horizontal motion of the Slipstick does not make this conveyor especially suitable for screening fine material out of a product stream. The Slipstick motion does not stratify a product bed by particle size so fines do not readily sift to the bottom of the material bed to come in contact with the screen surface. However, with a bar screen the conveyor can be used to scalp oversize material in some applications.

We have Slipstick conveyors in operation that were manufactured in 1974. Providing the machines are used for their intended purposes and routine inspection is carried out to ensure correct functioning, we believe all our machines should be operational for at least 25 years.

The Slipstick can be enclosed to ensure a dust tight seal. But the quick forward, slow return settles dust.