10 Ways to Enhance Conveyor Productivity 528 KB PDF, new window
Conveyors are the backbone of effective material handling systems. In this free downloadable document, you'll discover ways to enhance your conveyor operation from start to finish. From maintenance tips to problem-solving answers to testing advice, this quick-reading report is designed for conveyor users at any point in the life cycle of their operation.
There is an old story about a tree-cutting contest that you should know if you're running a conveyor operation. The contest was to cut the most wood in a one day. One lumberjack relentlessly swung his axe, working as fast as he could. The other stopped to sharpen his ax every hour—and despite the downtime, he won. To avoid breakdowns and optimize performance, conveyor needs to be “sharpened,” as well. Since conveyor downtime is painfully expensive, you should perform scheduled maintenance, check lubrication, and replace worn-out parts on time.
Service is expensive, and you can often avoid it by knowing the fixes to common issues:
The conveyor suddenly shuts down for no apparent reason. Reset the emergency stop buttons, which are located around the conveyor and are used to shut it down in case of an emergency. These buttons are often tripped by personnel or by packages stored too close to the conveyor.
Packages are accumulating in one area of the conveyor. There can be many causes for this, but in most cases the photo eye is dirty, obstructed or offset. Save yourself some money and time: check it before you call service.
The drive runs, but the belt doesn't move. Check your conveyor for an overload. You can eliminate this issue through training and intelligent load redistribution. If redistribution doesn't fix the problem call service. Load will not accumulate on one or more zones. Check the air lines for kinks. The air bags won't work properly if there is insufficient air. Also, check the air compressor for water since this can cause major problems with the pneumatic system.
The most common conveyor specification error is lack of detailed information on load data and application objectives. Often, load information is neglected and hardware is selected on an arbitrary basis—a recipe for poor performance and inflexibility. Examine the load in detail. Make a list of all of the units that will be handled on the conveyor. You can find a full guide to load factors here.
Other factors include:
All of these things could cause the box to act erratically on roller conveyors.
Conveyors are very energy efficient compared to the alternatives for moving product through a facility. Substantial energy and cost savings are possible. How can you convey more for less energy?
Know and understand your load factors to avoid a variety of issues. Misunderstanding load factors is perhaps the most common conveyor specification and maintenance error. We can assist you in tracking down the necessary information as you specify conveyor loads.
Select the right motor for the job. The motor should run at or near top capacity at all times. If load weights vary, use two-speed motors and adjustable-speed drives to enable motors to run near top capacity.
Keep the conveyor lubricated. Proper lubrication is a necessity in any energy efficient system using reducers, chains, and bearings. Besides saving energy, you'll increase the life of your equipment.
Turn your conveyor off when it's not in use. In some operations it may not make sense to continually switch them on and off, but you can efficiently do this in many cases. Intelligent controls can help by turning the conveyor off automatically when it isn't needed.
Use gravity feeds when possible. You can substitute gravity conveyor for power conveyor in the right situation, creating both equipment cost reductions and energy savings. Mixing power and gravity units to conserve energy and reduce costs is usually possible.
Design with energy savings in mind. Use long, straight runs with fewer drives. If possible, power the entire system with one drive. Use high-efficiency speed reducers. Replace worn-out conveyor. Modern conveyors designed more efficiently, with appropriate controls, deliver significant return-on- investment based on energy savings alone. Modern conveyors such as E24 DCV motorized roller slash energy use.
When elevation changes are necessary, choosing the right vertical transport device can make or break system performance. You have to take into account system throughput requirements, product characteristics, elevation change, number of infeed/discharge points, manual or automated infeed/discharge, interface with horizontal transport devices, proximity to workers, safety devices, environment, and future system requirements. Analysis of the above criteria will result in an optimum solution. In the unit handling world of a typical distribution center, examples might include vertical reciprocating conveyors (VRC's), continuous vertical conveyors, incline belt conveyors, spiral conveyors, chutes, and scissor lifts.
You've installed a new conveyor system, and you're ready to get into production.
Not so fast.
It may be tempting to turn your system loose, but you'll be money ahead if you allow time for adequate testing. If you do a cursory checkout, you miss the opportunity to fine-tune controls and detect hidden mechanical issues. Conveyor systems can have millions of moving parts designed to work in concert. Due to that complexity, a new system may need adjustments to perform. An outline of testing procedures:
Inspection: Visually inspect the entire system. This is about safety. Are all the guards in place? Are the pull-stops accessible? Are the safety stickers easy to see and read? The mechanical and junction boxes should be closed.
Function testing: Place a small number of items on the conveyor from the various in-feed points. This small amount allows for a controlled evaluation process. Look for obvious flaws; make sure all belts function, diverters and merges work properly. Be sure cartons don't hang up anywhere in the system.
Load testing: It's time to fully load the system to see how it performs at full capacity. Examine how high volume works, whether spacing between cartons is correct, or if any cartons bunch up. Overload areas to check how the system handles massive throughput and detect where any bottlenecks could occur.
Error recovery: These tests primarily check system controls. Errors are induced to confirm recovery procedures. Examples of errors might include barcode or RFID misreads, or products improperly inducted or removed from the system mid-stream. Additional “operator error” scenarios should be tested. Testers start and stop sections of the system to see how it handles these forces. Also check into “what if ” scenarios to see how the conveyor will react to unplanned events.
For instance, what would happen if an operator pushes two buttons at once or pushes one by mistake and then quickly pushes the correct button. It's important to see as many possible events as you can, so the system can recover as quickly as possible from operator errors. For large systems, it's advisable to keep both mechanical and electrical personnel on site for at least 14 days to ensure good system operation. Overlap this time with training time if possible.
Proper testing assures that a system works today—and in the future. A system designed to handle 80 units a minute might need to convey half that many in its first year. Don't wait to discover that it chokes at 65; test and find out. A system operating at a 20% capacity can look flawless, but might bog down at 80%. It's easier to make modifications during the testing than later on after the system is up and running.
Conveyors are a safe way to transport materials through your facility—in fact one of the safest ways—but they require training, process and vigilance to stay that way. Here's what you can do: Awareness: Part of the issue, unlike with many other kinds of industrial machinery, is that workers—and often managers—don't recognize the potential conveyor hazards. It moves slow relative to other machinery, and doesn't appear “threatening.” Conveyor might be seen more like a part of the warehouse than a machine that is powerful and can be dangerous if used inappropriately. Train new employees on how to use the conveyor, its on/off switches, emergency stops, and how to behave around it. And retrain your veteran workers to drive home the point. Nearly 42% of injuries around conveyors occur while performing maintenance, lubrication, or other mechanical processes.
Using conveyor in combination with workstations is an excellent way to boost productivity and increase safety. Musculoskeletal disorders can develop when workers lean, stoop, twist, or reach. These postures are also symptomatic of a less productive operation. A well-designed conveyor workstation eliminates risks and optimizes productivity. The two biggest factors are work surface height and reach distance.
Work surface height is the height at which hands are normally held to perform work on conveyed objects. Heavier tasks performed on larger objects require a lower work surface height than light, higher-precision tasks. Since people are different heights, one fixed height can't serve for everyone—and you can't alter the height of the conveyor itself. The thing to do is design the height appropriate to the load. If you want to vary it, design it for the taller workers and utilize step platforms for shorter workers. For standing workers doing belt picking or light assembly, the rule of thumb is about 42 inches. For seated workers, it's 30 inches.