Getting the Most Out of Conveyors
Optimizing your conveyor system
By Katrina C. Arabe
Choosing the best conveyor system for your application and making sure it delivers can get tricky. Here's how to select a system and maximize its uptime and flexibility.
Conveyors provide the solution to the most basic material handling
concern: transporting products from point A to point B in the warehouse
or distribution center. Maximizing the efficiency of these systems can
get complicated, however, as the list of considerations
can be daunting.
Several questions have to be answered: what type of conveyor is the best
fit for your application and once you have decided on a basic type, what
other factors should be part of your final selection process?
Furthermore, once you have purchased the conveyor—how do you make sure it will run as designed?
The following will guide you through the process of conveyor selection and operation:
Narrowing It Down
The first step is to determine what basic type of conveyor will deliver the best balance of throughput, return on investment and handling ease to your operation. Your selection process should start with a look at five of the most common conveyors: skatewheel, belt, sliding bed, live roller and accumulation. Each has its own distinct advantages and is particularly suited for certain applications.
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Skatewheel conveyors consist of rows of small metal or aluminum wheels. This system does not use motors—gravity does all the work—so it is best suited for bringing cartons, sacks and bags down a slope. Skatewheels are helpful in shipping areas, moving items down certain lanes for loading into outbound trucks. It can be hard to control the movement of products on these non-powered systems, however, so these conveyors are usually confined to short runs and accessible areas. On the plus side, they are cheap, low maintenance and often portable. In addition, some units can be expanded.
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Belt conveyors feature a motor-powered belt atop a constructed bed. These systems are widely used in facilities because of their ability to cost-effectively move a wide array of products. They have no problem conveying odd-shaped things and moving items up or down inclines because of the friction produced by the large surface contact area between belt and product. These conveyors can carry light- and medium-weight goods. Furthermore, these low-maintenance systems can transport products to almost any part of the warehouse.
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Sliding bed conveyors should be considered if you have to move unstable loads slowly. These systems usually consist of an unpainted metal surface that slides along a bed. Because of the generous surface contact area between the solid bed and the product, these systems excel in transporting odd-shaped products and small items that are not put into totes. These conveyors are commonly placed at load and assembly stations.
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Live roller conveyors consist of elongated rollers placed across a conveying bed. The size of the rollers can be adjusted to accommodate the product being conveyed. These rollers are powered by belts, chains or line shafts. Live roller systems can transport many different items so they are often selected by facilities with many assorted products. These conveyors welcome heavy loads and thrive in dirty or harsh environments. However, they can only transport items with solid bottoms and of adequate weight. Loose, lightweight products can fall between the rollers and should thus be placed into boxes or totes.
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Accumulation systems are useful for work-in-process operations or ones that need a buffer. These conveyors use rollers or belts that start and stop automatically to space cartons as directed by sensors. These systems can back up and set specific items aside without holding up workflow. They are widely utilized at workstations and for preparing items before they get sorted. These conveyors are more costly and need extra controls and motors. The added costs, however, can be recouped by the flexibility that these systems provide.
More Factors to weigh
The selection process does not end once you've chosen the type of conveyor that fits your application. Other factors should influence your final decision. For example, the type of controls must still be determined, with two common choices being programmable logic controllers and PC-based controls. In addition, the conveyor's noise level and energy consumption should affect your decision. Many companies have already invested in conveyors with high precision bearings that more than fulfill OSHA requirements for noise.
Although this option may increase the cost by 5%, it decreases worker fatigue. Energy efficient motors can also be a wise investment, given the instability of energy prices.
Another important option is modularity. Will your operation benefit more from a heavy-duty fixed conveyor system or a more recent alternative—the modular system? While fixed conveyor systems are reliable, they lack the flexibility of modular units. This shortcoming has become a more serious concern as many processes today call for frequent reconfiguration—sometimes even annual readjustments.
Modular systems directly address this requirement. They consist of self-contained modules—each section with its own power, drives and controls—which can be positioned to adapt to production flow needs. They are so versatile they can be set up around obstacles, move parts underwater and maintain production flow from fixed metal systems. Re-routing and relocation are a snap. Thus, if your application requires frequent changes in production runs, modularity should be one of the top selection criteria.
Now that you’ve Chosen…
Once you have purchased and installed a new conveyor system, the next step is testing the machine. "Most end users are in such an urgency to get beneficial use that formal testing is set aside," says Mike Palmison, vice president of systems and design at Dallas-based Cisco-Eagle, a material handling distributor and integrator. This is a big mistake because adjustments are often necessary to ensure optimal performance.
Testing is a four-step process that begins with a visual inspection. By looking over the entire system, all safety concerns can be checked off—such as the presence of machine guards, the accessibility of pull stops and the visibility of safety stickers.
Second, the examiners should run the conveyor and place a few items on it from the various in-feed points to make sure there are no glaring flaws in the system's basic function. Third, the system should be fully loaded to evaluate its performance at peak. In some parts, the conveyor should even be overloaded to examine how it handles high throughput. The final step is an evaluation of the system controls. Testers should push different buttons to simulate possible operator errors such as pressing two buttons at once or pushing the wrong button and then pushing the right one to correct the mistake.
Through evaluation, the system's short-term and long-term operation can be ensured. Testing the system's fitness today will spare you from future headaches. This evaluation process, preceded by a careful conveyor selection process, will allow your application to maximize the benefits provided by conveyor systems.
This article originally appeared on the
Industrial Market Trends Weblog and is published with the Creative
Commons license.
