Different types of conveyor systems and their advantages and disadvantages

Which conveyor or conveying system do I use for which application?

As a machine builder and total automation partner with a wide range of expertise in conveyors and conveyor systems, we are happy to provide more insight into different types of internal conveyor systems, which we design and build:

          1. Roller conveyors

          2.Belt conveyor

          3.Toothed belt or timing belt conveyor

          4.Modular conveyor

          5.Slat chain conveyor

          6.Chain conveyor

          7.Polycord, V-belt conveyor

          8.Vibratory conveyor

          9.Screw conveyor

1.Roller conveyor

One of the simplest conveyor systems are roller conveyors. The principle consists of series of bearing cylindrical rollers, over which products roll. Here we distinguish between gravitational and powered roller conveyors:

• Gravitational roller conveyors are under slight downward inclination of +/- 4 to 5 °, depending on the products transported, causing the products to roll down gravitationally. Here, brake rollers can be considered every so many rollers to slow down the descending products.

• Powered roller conveyors have 1 driven roll, where a transmission to other successive rollers is made by means of belts, cords or chains. The number of rolls driven by 1 motor depends on the payload, width, speed and type of transmission. Motorized roller conveyors can be designed very narrow – less than 100 mm – to very wide – 2,000 mm – making them attractive to many industries. Also, the mounting height can be extremely low -down to about 80 mm height (top of roll) in case of pallet conveying, which gives them compact construction options, such as multiple levels of conveyors.

Advantages

• Modular, easy to extend or shorten in design phase.

• Standard product which often needs little customization given its large presence in the manufacturing and logistics industries.

• Budget-friendly.

• Good sliding properties, allowing buffering with limited pressure in many cases (rollers rotating under products).

• Coating options, such as PVC sleeve on roll, to create more friction between roll and product.

• Suitable for curves.

• Compact.

• Attachments can be mounted between the rollers, such as tilters, box turners, transfer chains, pusher forks and more.

Disadvantages

• Products transported on roller conveyors are ideally supported by at least 2 rolls. Since the minimum roller diameter and the pitch between 2 rolls is limited, depending on payload and roller width, this means that some products do not qualify for roller conveyors. An example of this is pallets transported in width: the runners of the pallets are often too narrow to be supported by enough rollers for smooth transport.

• In the food processing industry, roller conveyors are frequently turned away for hygienic reasons, since bacterial formation inside the structure of the rollers is more likely than with other types of conveyor systems.

   

2. Belt conveyor

A common choice for conveyors are fabric  belt conveyors, consisting of typical belt materials such as PVC, PU, PVK and more. These belts are suitable as straight conveyors, as well as curves – although this requires a separate section. The belt material and their design strongly depend on sector and on the product to be conveyed, although they know their added value in numerous sectors – from injection molding industry to food processing industry. Because of their excellent hygienic and cleanable qualities, you often see these belts in contact with food. Because of their durability and strength, bulk goods can also be transported with this type of conveyor system. You often see these belts in combination with a belt control system to continuously adjust the belt if it starts to skew. There are electrical, pneumatic or mechanical solutions for this. The potential skewing of a belt can have several causes, but is typically a problem with fabric belts since the drive is primarily based on friction, and the fabric itself, because of its slimness, is not guided at the sides or bottom. In the food industry, these conveyors are often accompanied by a scraper to scrape dirt or food residue off the belt during production: something not possible with other conveyor systems.

It is also possible to adjust these belts in creative ways, such as a retractable nose or a hingeable nose to achieve for example a transition to another conveyor e in an efficient manner.

Advantages

• Excellent hygienic properties, where on the fly cleaning is possible through scraper.

• Easy to clean if, for example, the belt can be raised during cleaning procedures.

• Small nose diameters are possible for smooth transitions, benefiting small or fragile products.

Disadvantages

• Large tire widths become more complex and difficult to control, given a greater tendency for the tire to devolve skew.

• Fabric belts can slip under high loads or faulty design, eliminating accurate positioning of the belt.

3.Toothed belt or timing belt conveyor

If position tracking of the conveyor or the limitation of contact area with the transported product becomes important, timing belt conveyors offer a good alternative. The timing belt has a tooth structure on the underside of belt itself, allowing it to be driven by a sprocket. This does make the belt thicker and heavier compared to a fabric belt, however, the position of the belt can be accurately tracked and slippage is eliminated. No belt steering system is necessary since the timing belt can be properly centered and guided. The timing belt conveyor is often used with narrow belt widths, where several belts are mounted parallel to eachother, driven by one axis.

Advantages

• Precise and robust.

• Excellent hygienic properties.

• Belt steering unnecessary.

• The timing belt can be coated with numerous coatings to support special applications. For example, a soft coating or a very rough coating can be chosen to provide more softness or friction to a product.

Disadvantages

• The chassis of the belt becomes somewhat heavier and more complicated than that of a fabric belt, especially in the case of multiple parallel belts on 1 drive and chassis. Moreover, the continuous tensioning of the belt plays essential in precision applications, so its budget tends to be higher than that of the fabric belt.

• The diameters of drive and return rollers are larger than those of fabric belts because of the toothed structure and thickness of the belt: therefore, care must be taken with transitions for small fragile products (some overlap of two consecutive conveyors for example, might be necessary).

4.Modular conveyor

You will find the modular conveyor belt in the majority of industries because of its user-friendly modular properties. The belt material usually consists of hard plastic links that are attached to each other and are maneuverable in all directions: this makes the modular conveyor belt ideal for making turns and creating a large useful belt width. The drive is provided by a drive roller consisting of several star wheels with teeth, hooking into the links of the belt, which also keeps the belt centered automatically. Side guidance of the modular belt in straight sections is therefore not necessary. Replacing this belt is very easy and damaged links can be replaced with new ones without completely replacing the belt. The belt does not require to be kept under tension, it may hang loose on the return side. Several versions of the modular belt are available, from belts that hinge only up and down for straight transport sections to highly flexible variants that can be torsioned and rotated in all directions, as in spiral towers. These types of belts can also make very small transitions with a micropitch nose. In addition, toppings can be added to the links, such as rollers, to provide pressure-free buffering, for example.

Advantages

• Modular in length and width, easy to replace or adjust.

• Micropitch nose possible.

• Single section with single drive can accommodate multiple curves and adopt large lengths depending on product, speed and belt material.

• Easily cleanable and suited to use in the food industry (bakeries for example), as well as the pharmaceutical industry.

• Ideal to use as buffer belt, as 2 belts can be seamlessly set up next to each other.

Disadvantages

• For some foods, such as sticky foods (meat, chocolate, brownies for example), these belts are less suitable because of the many hinge points and lack of scraper.

   

5.Slat chain conveyor

Slat chain conveyors (“flat top chain conveyors”) are also basically modular, with slats hinged together with chain links. They score tremendously well on long conveyor lengths at high speeds, and they tend to be narrower than modular conveyors. The underside of each slat is lined with 1 single chain link per slat, allowing drive with a single star wheel. Some slat conveyors are flexible in both horizontal and lateral directions, thanks to recesses on the sides of the slats, allowing perfect bending. Others are suitable for long, heavy, straight-through applications, such as, for example, in breweries for transporting kegs and bottles, where the top is flat and smooth. Materials range between plastic and stainless steel, and there are hundreds of types of slat chains for a variety of applications. The slats can be coated with a variety of materials or contain attachments, allowing for endless applications. However, due to the presence of chain links, a small nose diameter is not possible.

Advantages

• Many applications and choices in design of slats.

• Easy to add, replace or remove slats.

• Sharp bends and long sections possible at high speed.

• Easily cleanable and good for use in the (wet) food industry (box or bin transport for example), as well as the pharmaceutical industry.

• Ideal to use for buffer belts, as 2 belts can be seamlessly installed next to each other.

Disadvantages

• For some foods, such as sticky foods (meat, chocolate, brownies for example), these belts are less suitable because of the many hinge points and lack of scraper.

• Micropitch nose not possible.

6.Chain conveyor

Chain conveyors are preferred when products with few support points and often high weights need to be transported, sometimes with a very high degree of hygiene and cleanability. An example of this are totes, pallets and pallet boxes in wet conditions. Usually 2 or more tracks or strands of chains are guided over a flat plastic or (stainless) steel platform or over 2 narrow chassis, driven by sprocket. Given the narrow characteristics of the chains, this transport system is suitable for corner transfers from roller conveyor to chain and vice versa.

Advantages

• Excellent cleaning with high pressure due to its open structure

• Ideal for heavy loads

• Excellent in wet conditions if made of stainless steel

Disadvantages

• No curves possible.

• More expensive than roller conveyors.

• Due to the chain structure, it is not recommended to accumulate products with pressure where the chain spins under the products.

7.Polycord, V-belt conveyor

Staying in the theme of narrow conveyor belts with a limited contact surface, as in the case of the chain belt or the timing belt, the polycord belt conveyor and the V-belt conveyor join the list. The difference is flexibility: it is much higher especially for the round belts, since they are maneuverable in all directions. These potentially extremely narrow belts are manufactured by extrusion and consist mostly of rubber or PU, optionally reinforced by internal steel wire. As a result, these conveyor systems score well in elasticity. The welding of these belts is also quite easy with the right craftsmanship. It goes without saying that these belts are excellent for use in hygienic environments with excellent cleanability, which is why we often find them in the pharmaceutical and food industries. But above all they are useful in the transport of fragile scratch-sensitive products, such as aluminum profiles, tiles or glass. They are driven by pulleys with grooves, based on friction. Multiple tracks or strands are often used to support products at different points. It is important that the belts are always kept under tension given their high elasticity properties.

Advantages

• Excellent cleaning with high pressure due to its open structure, just like the chain conveyor.

• Very high degree of hygiene.

• Ideal for lighter or fragile products.

• Average sliding properties and soft material, different coatings possible for V-belts (e.g. increasing resistance, smoothness,..).

• Excellent in wet conditions if chasses made out of stainless steel.

• Curves possible if round belt.

• Completely dust-free.

Disadvantagtes

• Designing this type of belt often requires a high degree of expertise, given that they are often used for fragile products.

• The budget of this type of conveyor belt can add up, depending on the design.

• Long-term buffering with pressure, where the belt passes under the products, is often not recommended.

8.Vibratory conveyor

The most easily cleaned conveyor type is the vibratory feeder. The vibrating feeder consists of a plastic, steel, aluminum or stainless steel tray or chute, under which a vibrating motor and suspension/damping points are attached. The speed and mechanical eccentricity of the shaft of the vibrating motor determines the transport speed of the goods to be transported. A vibrating chute is often used for narrow and short infeed points of small products (for example, caps or the like), or just for large erratic goods such as in the waste processing industry or the food industry.

Advantages

• (Mostly) easy design and construction

• Excellent in cleanability

• Robust

Disadvantages

• Noisy

• Limited in speed

• Hard to position and dose products

9.Screw conveyor

When one wishes to transport powders, granules, waste or pastes (vertically or horizontally), screw transport or “screw of Archimedes” is old hat. Often this involves customization and the design is highly dependent on the product, transport speed, viscous properties of the medium to be transported and more. A screw conveyor is often closed in structure in a tubular housing or semi-open trough. This type of conveyance is mainly found in the food industry, pharmaceutical industry and plastics and waste processing industries.

Advantages

• Ideal within the process industry for bulk goods

• Excellent hygienic qualities, however due to the mostly closed housing the cleaning is less visible and the procedure can be more intensive (CIP for example) than simply manual rinsing with lance

• Robust

Disadvantages

• The screw poses a danger to people, so it should be shielded at all times

   

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