In a modern plant, conveyor systems are becoming more of an expectation than a luxury, and where there are multiple conveyors, there are probably some choke points where boxes can get bunched up. The best way to solve this issue is through the use of automatic indexing.
If you are simply transporting boxes with your conveyors, tight quarters might not hurt (unless you are trying to converge lanes), but if you are doing any weighing or labeling, some sort of indexing is going to be a necessity.
Modern automatic labeling systems for boxes are fairly fast and accurate, but that doesn’t mean that they can just label a steady stream. With a print-and-apply system, the labeler needs time to print the next label before it can apply, so you are going to need to space out your product to give the labeler time. Also, certain label applicators require more room, like a front of box labeling applicator because it often requires an arm to swing out and then back between boxes.
Automatic weighing with conveyor scales or checkweighers requires spacing because you can only have one product being weighed at a time. Imagine two boxes back-to-back. At some point in the weighing process, you would have both of them on the scale. This would give you an excessively high weight reading that would be completely useless, and even worse, could damage your load cell.
So what are your options?
The deceptively cheap way is to have employees space boxes by hand, but this doesn’t always turn out as planned and paying someone to do it is an accumulating cost. You could also use “traffic cop” sensors to start and stop your conveyors. This works well for the most part, but it could wear your motors out faster, increasing maintenance costs. Some companies use higher speed conveyor sections to put distance between boxes, but this can take up more floor space than necessary depending on required spacing.
The best way that we have found is to use an indexer conveyor. Our solution is to use a conveyor mounted on a pneumatic cylinder which drops at one end allowing boxes to run into a retaining bulk head. The conveyor can then pivot up and down, allowing only one box at a time to get by. It often uses roller conveyor which relieves the box from friction and utilizes a small speed-up roller which pulls the box away from the one behind it when it is released. Indexing is a very sound method that is capable of giving you exact spacing.
We have dealt with systems that use all of these methods, so if you have any questions about indexing and how it could help your process, get in contact with us.
See a Box Indexing Conveyor
Indexing conveyor systems are a plant’s answer for the need to combine multiple lanes of product. This essentially makes them a traffic cop for your boxes and packages.
Indexing conveyor systems require careful planning and timing to make sure that all your products are moving down the conveyor with appropriate space. Occasionally, problems arise that might disturb the timing of indexers.
One area where things can go wrong is that of the photo eyes. If they aren’t aligned correctly, the timing of the system could be off. Sometimes, this occurs because a photo eye has been bumped and skewed which causes it to set off the indexer at the wrong time, or not at all in a worst case scenario.
It isn’t always a physical adjustment that can throw a photo eye off course. There is instructional machine code that interfaces the photo eye with the rest of the system. Sometimes, when this machine code or models of photo eyes are incompatible, it can cause issues that cause them to read incorrectly. We solve this issue with an in-house programming department that takes care of all of those issues before they occur in-plant.
In terms of physical maintenance, there is another issue that can arise when using certain indexers. Especially when using start-and-stop indexers, you can end up with wear issues. When using a motor that is stopping and starting all of the time, you will find that it starts to stress the motor to a point where you might need to replace it far more often. Our best solution for this problem is using mechanical stops that keep the motor and belting running, while product starts and stops. This section of conveyor uses rollers that allow the product to flow across the top without putting excessive friction on the conveyor surface.
We understand that machines don’t always work how you would like, but there is almost always a viable solution waiting for that issue.
See a Box Indexing Conveyor
There are a lot of ways to give products the ideal spacing that they require. The method that we use the most is drop down indexing. Rather than stopping and starting the conveyors, we use a section of conveyor that drops down to temporarily stop products while continuously moving the conveyor. It is a handy piece of technology, but you have to make sure that it doesn’t cause undue stress to packages.
The drop down indexer stays down until the timing is right for the conveyor to pop up and allow the package to travel forward. A friction belted roller essentially grabs it and speeds it along the belt to put space between it and the package behind it. This gives the indexer enough time to drop back down before it accidentally feeds two boxes.
An important thing to watch out for is a backed-up line of boxes. The indexer itself uses free-rotating rollers in the belting to counteract forward pressure, but the conveyor prior to the indexer might not. If boxes start to pile up from the indexer onto the previous conveyor, the boxes at the front of the line could be placed under tremendous pressure.
When the indexer pops up with this pressure, the leading box could burst forward violently causing box collisions and timing errors. A good way to keep this from happening is by installing belting with relief rollers on the conveyors prior to the indexer. This takes excessive forward friction out of the picture.
Another way to prevent damage to both your products and your indexer is by knowing what the structure of your indexer is rated for. We have had people request indexers meant to carry a certain amount of weight, only to have them load far more on the frame.
If the system wasn’t made with large boxes in mind, the force on the indexer and the torque created by other boxes on the line could damage the frame and even the piston system.
Treat your indexer right, and it should work well and have a longer operational life. There is no better tool for preparing your products to be labeled or weighed by a conveyor scale.
An indexing conveyor system is designed to keep product properly spaced so that labeling units, conveyor scales, product inspection stations, and even pack-off areas do not get jammed or overwhelmed.
When you find your indexing system failing to do its job, here are three common failure points and possible solutions.
Slow Pop Up
Many indexing conveyor systems stop the forward progress of the product by suddenly dropping down, sending the product into a rigid abutment. When it is time for the product to resume its travel, the conveyor must pop up quickly enough for the product to take its proper place in the production line. When the pop-up stop is slow and lethargic, that product could miss its opening and the items behind that product could pile up as well.
Usually when the pop up is slow, it is due to insufficient air pressure in the line. Check the manual for the recommended amount of air pressure and make sure the line is getting an amount that is within range.
Failure To Stop Product
An indexing system must sense when a product is within range and that there is a need to interrupt its forward progress. Occasionally this operational point can fail and products proceed unhindered.
This problem is usually a photo eye alignment issue. It is easy for photo eyes to get bumped in the hustle and bustle of daily work activities. A small misalignment may not be obvious to the naked eye, but it could be enough to prevent the indexing system from detecting the presence of a product.
Sometimes the indexing systems drop down too early and sometimes it pops back up too late. When these symptoms are present it is almost always due to timing errors in the system controller.
This can be the most difficult area for most plant maintenance people to fix because timing errors usual reside in the programming. Unless you are reasonably certain that you can successfully tweak the program, chances are this is one error where a call to our service department is your best option.
Whether you need to replace an old, failing indexing system or build one for a whole new line, we’ve got the experience and knowledge to design it right and make sure it works as intended!
You may have several conveyor lines in different areas of production operations and desire to join those lines together at various points. Space is always a premium and such activity such as automatically merging material to specified locations can be a masterful stroke in overall efficiency.
For example, various items could be packaged and sent on their way to a shipping location. As items head on their way from one department, they could be weighed, labeled, and sorted accordingly to specific shipping points. The items may be relocated to other conveyors by pneumatic push, pull, or drop divert actions according to specified settings in a control system. Controls can be triggered by weight, label designation, or simply set dimensions recognized and triggered by photo eye placement.
Sometimes items simply come to a main conveyor belt by virtue of progression down gravity fed rollers and subsequently dropping lightly in a specified place. Physical placement may sometimes be introduced according to mechanical manipulation. For example, a box may be held in place or released according to a triggering device. Most often, this is referred to as an indexing system.
In addition to indexing placement, items sometimes gravitate, or are power merged by use of directional belting. This may occur prior to, or in conjunction at the point where one belt meets up with another. Speed is sometimes increased on some belting to enhance product separation prior to other possible activities down the processing road.
Occasionally, where hand selection of small circular containers is necessary, product is introduced from a smooth angular belt a smooth circular table where people may be gathered to provide specifically required manipulation and handling.
In some cases, such activity may be entirely robotic.
Thus, there are many methods of conveyor convergence. You just need to determine what is logical, efficient, and economically correct for your needs.