No matter what kind of products a manufacturing line produces, an effective conveyor belt system is key to ensuring safe and well-organized material handling that maintains the operation’s rhythm. Most conveyor systems achieve this with a combination of both standard and pallet conveyors at various stages of the line. Knowing how and where to use each requires an understanding of their differences and how those differences impact their functionality.
By Marco Pardo • Product manager | Dorner
Pallet conveyors allow products such as pharmaceuticals to be held in place for meticulous assembly and processing. Image: Dorner
The primary difference between standard and pallet conveyors is item placement. On a standard conveyor, items come in direct contact with the belt that the model uses to move goods. A pallet conveyor offers a degree of separation with an elevated platform to transport items. Instead of placing items directly onto a moving belt, these systems feature a track with pallets that can switch directions and skip stations more easily.
Generally, pallet conveyors are used for assembly processes, while standard belt-driven conveyors transport products through secondary packaging and end-of-line functions. There are several reasons for this pattern and a few exceptions that prove there is no one approach to conveyance.
Precise placement
Though stop-and-go options are available in standard conveyors, they will never offer the same level of precision as pallet options. With each product on its own platform, the placement and orientation can be standardized for easier assembly. Some modules can communicate with other line components to locate the pallet within a thousandth of an inch. This communication is critical for any assembly involving automation, as robotic arms cannot adjust in the same way a human worker can.
Even with human workers, the proper placement and control of a pallet conveyor are hugely important for efficiency. Despite the growing presence of robotics in assembly, the complexity of some work still requires human hands. Building cell phones, car headlights, and hundreds of other products involves a network of intricate parts, small screws, and fine detail work. The complexity of the line is precisely why pallet conveyors are the go-to option in these scenarios. A pallet conveyor securely transports each item at the correct pace, stopping at workstations for each process step. Workers can perform their tasks on stopped items that are properly oriented when they reach the station, improving efficiency.
Guidance systems can help move items around tight turns securely within a small footprint. Image: Dorner
In addition to placement on the pallet, these individualized units also give the line operator more control over how products are positioned on the line itself. Standard conveyors are like trains, where products move in one continuous line, and redirecting that line requires changing the tracks. Pallet conveyors move more like railcars, as each unit controls where it goes. If an item needs to skip a step or go in a different direction, that can be programmed into the pallet to occur automatically utilizing RFI or other similar technology. This separation also benefits the user if there is a malfunction. While any disruption on a standard conveyor shuts down the entire belt, most problems with pallets can be isolated and the individual unit removed for the necessary maintenance.
Space to breathe
Another benefit of pallet conveyors is the lack of accumulation pressure on the products. Some steps are faster than others in most assembly lines, and products tend to bottleneck between stations at different speeds. These stack-ups can also occur when another component, either upstream or downstream, stops running while the rest of the line continues to function properly. When raw parts accumulate on a standard conveyor, they are all touching and bumping into each other. The belt does not stop running, but the part does, and pressure from all the other parts around it builds. With a pallet conveyor, individual pallets can stop anywhere and space accumulated items apart from each other. Even if they touch, the pallets absorb all that pressure to preserve the items they carry.
Pallet conveyors easily transport platforms from one belt to the next to reach all the necessary workstations and ultimately reach the final destination, all within one system. Image: Dorner
Preventing parts from touching each other when they bottleneck is nearly impossible on standard conveyors, but they do offer a solution to prevent excessive pressure. For products that can withstand some force, accumulation tables provide a mid-line storage space. They can be adjusted to move, hold, or redirect products within seconds to keep operations flowing without interruption.
No assembly required
Despite their drawbacks in the detailed assembly stages of a line, standard conveyors have their place in nearly every operation. Once the individualized components of the line are complete, products move into batch functions, such as sorting, packaging, and storage. Standard conveyors work well with the consistent motion of these operations, ensuring that each step has a steady supply of products for maximum output.
Some products also work best with exclusively standard conveyors. For example, beverage manufacturing is a relatively simple process where drinks are bottled, capped, shrink-wrapped, and palletized. The steps are simple enough to be fully automated, and the products are durable enough to withstand pressure from accumulation. In situations like this, placing each individual product onto a pallet would slow down the operation and take up too much space in the warehouse.
One size fits one
Deciding whether a line should use standard conveyors, pallet conveyors, or a mix of the two is largely based on the steps in the manufacturing process. However, this is only the first step in finding the specific conveyor solution that best fits an application. Expected output is an important consideration that will determine the necessary robustness of each conveyor on the line. Other factors, such as cleanroom and wipe-down requirements and additional regulations to the line, are equally critical in determining which machine to use.
When adding conveyors to a line, manufacturers should think of them as a system, not individual belts. No matter what combination of standards and pallets are implemented, the best solutions come when they all work together for seamless, connected, rhythmic material handling.
Marco Pardo is a product manager at Dorner and can be reached at [email protected].
Dorner
dornerconveyors.com
Filed Under: Material handling • converting
