Box Indexing Conveyors are a helpful and sometimes necessary process for weighing and labeling.
For operations with a high throughput, product spacing is hard to manage without some sort of indexer. However, before you install a box indexing conveyor system, it is very important that you know the limits of your operation.
Because of the nature of drop-down box indexers, the system has to withstand a lot of stress by lifting boxes up and down on a small section of movable conveyor.
This being said, it is quite easy to build an indexer too lightly without complete knowledge of products coming over that conveyor. It is extremely important, especially for us, to know the range and size of any products that might make their way across our indexers.
Let’s look at an example where under-specifying can go tragically wrong.
Imagine that our customer has given us an accurate weight range for their products. That is obviously a good thing, but what if they didn’t give us the smallest package dimensions?
It is quite possible that the indexer would be large enough to hold more than one box which could in turn multiply the live load beyond what the design was meant to hold.
Since we build systems to the specs that our customers indicate, the wrong specs could be disastrous.
There have been stories of customers attempting to put 100 lb boxes onto conveyors made for boxes that are only 40 lbs. This sort of overloading is very bad for the frame and the air cylinder, so it is best to never undershoot your weight range and product sizing.
When mixing products going into an indexer, it is important that the disparity in weights between products isn’t too great as well. If a lighter box were to enter the converging area directly followed by a heavier one, the collision could cause significant damage to the lighter box.
These are just a few of the indexing tips and tricks that we have picked up over the years, but we hope they help.
If you need an indexer for your important processes, you can look to us to take care of the details.
The role that indexing plays in maximizing your plant’s throughput can hardly be overstated.
Without proper spacing of products on an in-line conveyor scale, weighments will not be accurate because more than one product could be on the live section of the scale at the same time.
But to rely on an operator or production rates to create enough space between boxes or cases is in actuality depending on luck.
It is only a matter of time before your luck will run out.
The approach we take when Indexing for Box Merging or for Automatic Case Labeling applications is to place a photo eye just ahead of a box stop to sense the arrival of a box or a case.
This box stop section consists of a powered section on the conveyor with roller top belting that drops down to hold back the boxes.
The roller top belting helps prevent damage to the box bottom by greatly reducing the amount of friction applied to the box bottom.
At a settable time or length interval, the Indexer rises, allowing a box to progress down the line.
Our preferred method of restarting boxes down the line is through the use of a speed up roller to help pull a gap.
A speed up roller uses friction belt and runs at a faster rate of speed than the In-feed conveyor.
As soon as a box reaches the midway point over the stop, the indexer drops again to detain the trailing box or boxes.
This process continues unless box spacing is great enough that detaining a box is not necessary.
An indexer puts you in control of the vital function of proper spacing of your products, while eliminating the labor expense associated with staffing someone to perform this function.
Rather than slowing down your process, proper indexing helps ensure that you are getting the most throughput possible.
It is hard to place value on automated systems just because they are based on an opportunity cost.
When you need an estimate for the value of an box indexing system, you need to know things like the box throughput that your system handles and the number of employees that it takes to do the spacing of your products.
Indexers act similarly to a set of photo eyes acting as a traffic cop.
Where the traffic cop setup can stop an in-feeding line to prevent product collision, an indexer can momentarily stop or delay a package to eliminate crowding on the line.
The difference is that using an indexer allows the conveyors to continue moving, which is of great importance for some operations.
The indexer works by dropping a portion of conveyor down slightly so that the package stops. The conveyor stays lowered until the system receives a signal that lets it know when the preceding product is far enough away.
When that signal comes in, the conveyor pops back up and the box continues onto the next conveyor. The conveyor then drops again to stop the next box if spacing is too close.
There are all many components that make this system work right. To avoid friction that can cause conveyor damage, the indexer uses a belt with embedded rollers that moves it forward when unhindered, but allows the conveyor to move freely beneath when the box is stopped.
You can also use a speed-up roller after the indexer to “grab” the boxes with a high friction surface and propel them ahead of the box behind them.
The fact that the indexer can perform such a repetitive motion with machine precision allows you to eliminate a highly menial labor task, increasing both your income and efficiency at the same time.
Variety in automation ensures that the industry is always moving forward and that there is a solution for every problem. However, the differences among varieties are not always obvious.
This is true with indexer types, so we’re going to look at some of the most common ones in the market.
1 – Speedup Conveyor
While not an indexer in the traditional sense, having a conveyor that runs faster directly before weighing can achieve product spacing.
This method works well with consistently sized products, however, can fail completely when product size varies dramatically. It can work in some situations, but the spacing is still dependent on how close the packages were before this conveyor, and the conveyor doesn’t do any sort of aligning.
2 – Drop-down Indexers
This is one of the types that we use most commonly. The indexer is a section of conveyor attached to a pneumatic cylinder. When photo eyes see a product, the cylinder brings the conveyor down so that the product is retained by a stop. When photo eyes or a timer tell the indexer that there is enough space between the previous product and the retained product, the air cylinder moves the conveyor back into the neutral position and the retained product progresses down the conveyor.
This system allows for very controlled spacing and packages tend to align themselves during the indexing process, which makes them easier to label accurately. This indexing method is commonly paired with a speedup roller to ensure a gap is pulled to accurately index.
3 – Pop-up Indexer
A pop-up indexer is a system where a barrier pops up between two conveyors to block forward motion.
This one is used mostly for boxes. It has less overall moving parts than a drop-down conveyor, but it is less effective the closer products get because the stop needs to be able to find a gap between packages.
4 – “Squeeze” Indexer
This type of indexer simply uses plastic wedges that swing in from the sides of the conveyor to pinch off flow when the system needs to stop it.
This is usually used with boxes or things with rigidity because of its nature.
This is also used often in a traffic cop role to stop line flow when you need to combine multiple lines into one.
We generally go with the drop-down indexer because of its versatility and because it works the best for separating tightly packed products, but there is a time and place for each of these indexer types.
Learn more about our Box/Case Indexers