There are many items to consider when selecting a conveyor type for a project. Each item has its own importance and will impact conveyor selection. Use the following criteria to make the best choice for your operation.
1. Product Specifications
Product specification is hands down the most important item when selecting a conveyor. Let’s start with the basic product specifications:
You will need to determine the length, width, and height of the product. These dimensions will determine conveyor specifications such as, conveyor width, roller centers, guide rail specifications, transfer needs
You will need to determine the weight of your product as well. The weight of the product will determine many aspects of the conveyor selection. For example if the you are using a plastic chain conveyor, the product weight will determine how many curves can be included in one conveyor. If you are using roller conveyor, the product weight will help determine things such as roller diameter and roller guage requirements. Product weight also has a great impact on the motor sizing for your conveyor.
Product Rate (Production Rate)
The production rate of the product is most commonly measured in parts per minute or parts per hour. The product rate, along with the product length, will allow you to determining the appropriate conveyor speed so that your conveyor can meet the production rate. For example if your product is a 12” long case, and the product rate is 30 cases per minute, then your conveyor would need to run at least 30 feet per minute to accommodate the product rate with no gap between cases.
There are many different types of products, and each type conveys differently from the next.
For example if your product is a wooden pallet, then a chain driven live roller conveyor may be the best selection. However if the pallet is a plastic footed pallet, then a large plastic chain conveyor may be a better solution as the pallet feet may not convey well on roller conveyor. Another example, if your product is a bag of cereal then a plastic chain conveyor will convey this product much better than a roller conveyor.
2. Accumulation Requirements
Accumulation requirements are very important when selecting a conveyor. Accumulation is a common requirement in a production environment and is vital to reducing downtime if a piece of equipment such as a palletizer goes down. When reviewing your accumulation needs, take into account the product information as well. For example, if you need to accumulate 300 feet of cases prior to a palletizing cell, then a zero pressure accumulation system would be ideal to avoid excessive back pressure on the product.
Another example would be if you need to accumulate five cases of product at the end of a line for a manual operation, then a minimum pressure accumulation system may be sufficient. Should you need to accumulate bagged product such as a bag of cereal, then back pressure on the product may cause the bags to shingle on top of each other resulting in jams and product damage.
3. Guide Rails
Guide rails can be an excellent addition to a conveyor but can also cause problems if improperly selected. Guide rails are not always required, but when they are, make sure the space between rails allows for your product to be conveyed as desired. One area of the conveyor where guide rails can cause issues is in the curved sections. Always make sure you have proper rail spacing to allow for product to convey around a curve, as more width is required in a curve than in a straight.
Also some products do not react well to guide rail and special attention to the guide rail design should be made to accommodate these products. For example, a bag or pouch of liquid cheese; this product is flexible and instead of impacting the guide rail and reacting like a rigid case, it can easily form around the rail, going under the rail and jamming or turning the products orientation if the guide rail system is not properly designed.
4. Washdown Requirements
Washdown requirements can greatly impact the selection of conveyor on both price and conveyor construction. Most warehouse environments do not require a washdown rated conveyor, so a mild steel or aluminum bolted construction conveyor will be sufficient. However many applications in food, dairy, and pharmaceutical industries require different levels of washdown rating where stainless steel conveyors must be used.
Conveyor Washdown Considerations
Water Pressure: Some washdown environments are only required to withstand wipe down levels of cleaning, while others must be able to withstand high pressure water. If high pressure water is used, then items such as the motor must be rated for this level of cleaning.
Cleaning Chemicals: When reviewing the washdown process, be sure to determine what chemicals are used in the cleaning agents. While some washdown processes only use water and mild detergent, others can use harsh chemicals such as chlorine. Be sure to determine the compatibility between your conveyor materials and the chemicals. For example, high levels of chlorine may damage acetal plastic, which is a common material used in plastic chain conveyor.
Conveyor Construction Requirements
For high level washdown environments in the food and dairy industry, conveyor construction is a major component in passing inspections. Some washdown environments allow a bolted construction, while others may require no overlapping surfaces with bolted surfaces to be mounted on stand offs. Some washdown specifications will not allow for bolted construction and require frames to be welded.
Another area of the conveyor construction to consider is the chain or belt. Many washdown applications use plastic chain conveyor; however, in areas where you handle raw meat or cheese, then plastic chain may not be acceptable due to the USDA requirements, and an endless belt with no joints must be used.
5. Environmental Conditions
Environmental conditions are often over looked or never explored when selecting a conveyor system. It is important to understand what the environment, in which your conveyor will be placed, is like. For example, if you are handling metal parts, then you may have cutting oil residue or metal machining shavings make their way into your conveyor, causing malfunctions.
Another example, if you are handling cases of bottles that contain liquids, then you may from time to time have a leaking bottle. If the bottle leaks, then the contents of the bottle can get onto the conveyor causing product to slip on inclines, or cause malfunctions in the drive assembly if the conveyor is not designed to handle the environment.
6. Product Transfer Requirements
One of the most important areas of a conveyor system is the transfer of product to and from the conveyor. There are many styles of product transfers such as gravity rollers, dead plates, powered transfers, side to side transfers, and so on. If you are transferring a 24-inch long case from roller conveyor to roller conveyor for example, then a transfer may not be needed. Another example would be if you are transferring a 5-inch diameter roll of tape from a plastic chain conveyor to plastic chain conveyor, then a powered transfer may be needed, due to the short foot print of the product.
7. Incline/Decline Requirements
As industry grows, floor space becomes more valuable, and often times, product is required to incline or decline to different floors or over existing equipment. Elevation change can cause serious problems if the proper conveyor is not selected. For example, a 24-inch square case weighing 40lbs will not incline at 80 degrees on a standard slider bed style conveyor, for this you may have to look at a spiral conveyor.
There are many different styles of incline/decline conveyors, such as belted conveyors with different material high friction belts, plastic chain conveyors with high friction inserts, spiral conveyors, wedge conveyors, and cleated conveyors. Product testing prior to conveyor selection is always a plus.
These are just some of the main items to consider when selecting a conveyor style for a project. Conveyors are often not viewed as important as other pieces of equipment in a project, but without proper conveyor selection, the product may not be able to make it to the other pieces of equipment in the project. The next time you’re selecting conveyor, be sure to gather as much information as possible; the more information you have, the better the final solution will be.