When designing a system where a decision is being made by that system’s controller for an action to be taken further down the line, you have two methods to choose from for that controller to make the action happen. One is time-based the other is encoder-based.
The time-based option operates very simply. Let’s say that a product is being weighed in motion to determine a certain line that the product should be sent down. Once the products weight has been established by the controller and the appropriate location has been determined, the controller will have been programmed to know that the line is a certain amount of time away, so it will begin counting down, and when that countdown ends, a divert will be activated to send that product down that line.
This is a very simple and effective system as long as nothing ever changes, like line speed. If the line speed is sped up, the product would be past the proper divert before it was activated, and if the line was shut off even for a brief amount of time, all of the timing could be thrown off.
To safeguard against this, we like to use an encoder-based system. To explain what an encoder is, basically, the system’s controller will count how many times the shaft on the conveyor turns. Now every system is different but let’s just say that, with this system, every time the shaft turns one time, the conveyor belt will travel six inches. So, with this encoder-based system the controller will have been programmed to know that the divert is a certain number of shaft revolutions away, and all it has to do is count these revolutions and then activate that divert. With this system, speeding things up, slowing things down, or even stopping the system will not affect the process.
That was a very basic description of an encoder. Encoder technology is actually much more advanced than that. In the previously mentioned system, the encoder would send one electrical signal to the system controller for every revolution of the shaft signaling six inches of travel. If this encoder were to send two electrical signals for every shaft revolution, the system’s controller would know that every electrical signal from the encoder would be equal to three inches of travel. Four electrical signals from the encoder would mean each signal would equal one and a half inches of travel.
Encoders are available that can send over one thousand electrical signals for each revolution of the shaft. This can allow for very accurate tracking of anything on a conveyor.
When it comes to sortation, the product is always the most important factor. Sortation and classifying systems need to be designed in a way that handles the product with care, so that damages aren’t sustained by the product or the system itself. We’ll show how this is so important by taking a look at a loin sorting system that we recently created.
When we designed the classifier, we had to first think about any difficulties that one might run into when handling loins. These particular loins were roughly nine inches wide and two feet long. The first design decision made was that the loins would travel with the short dimension leading because this used much less floor space. If this wasn’t decided, each conveyor section would have had to be over 3-4 feet long. Orienting it like this made the system about half as long, while only increasing its width by about a foot or two.
Because the loins were traveling width first, there were a few handling considerations that came into play. The loins are generally round around the bone, so with a normal conveyor setup, it was possible that the loin could roll slightly into the gap between conveyor sections. This could cause damage to the loin, and it could cause fat to be stripped off of the loin which would cause the conveyors to accumulate buildup and cause the accuracy to be off because of added dead weight on the conveyor scale.
This was solved by cascading the conveyor sections. This simply means that each conveyor was set up a little higher than the following one. Rather than passing directly over the gap at each conveyor transfer, each loin would gently fall, bypassing the gap entirely.
The only thing to be careful with was the transfer between the infeed and the scale conveyors. A large drop between the two could cause poor weighment readings. When a scale is constantly shock loaded, detrimental effects can take place. The cascading between these two conveyors was very small, but enough to get the job done.
Finally, at the end of the system, these loins needed to be diverted. With the loins facing width-wise down the conveyor, linear thrust diverts and push/pull-off diverts would be very difficult to use as the loins might not respond ideally to outside force. We used pop-up conveyors to allow the loins to drop below the conveyor instead, which solves any problems due to orientation.
This is another example of how we are able to work out all of the little details in every system that we make.
Upgrades to plant equipment often come in tandem with trends because of a meat market with fluctuating prices. Currently, pork seems to be the most profitable endeavor, as we see a lot of interest in various systems for weighing hogs and sorting various cuts of meat.
It makes sense that equipment would be improved in the market with the highest profit because it allows the companies to make the most out of that upswing. At the same time, it improves efficiency for processing meat when it isn’t making as much profit so they can add a little extra to the bottom line.
Because of these trends, the high throughput for pork requires new ways to handle products. In the case of ribs, a sortation system can make the perfect addition.
When you look at the rib market, there is a large amount of variety. There are multiple different types of ribs based on where they were cut from and how they were cut. For example, baby back ribs are cut from the loin while spare ribs are cut from the belly. The spare ribs generally have more meat, while the baby back ribs are more tender.
The distinctions between ribs get even more confusing after that. As another example, companies will sometimes cut spare ribs down to be more like baby back ribs, and these are called “St. Louis” ribs.
If the variety of rib type wasn’t enough, customers buying ribs often ask for a large number of different sizes and weights based on their needs. Smokehouses and restaurants will want sections of ribs at an ideal weight, while a co-packer might want entire sets of ribs or large sections which they can work into more specialized cuts.
An automatic sortation system is perfect for this type of environment. Rather than having a dozen employees responsible for all of these different criteria, you could use one machine. Compared to the employees, the sortation system doesn’t get tired or make errors in judgment.
A sortation system can easily be customized with as many drops as a customer would want, and it can sort those ribs by any information which you can put into a database, such as sorting by both weight and type. This allows you to accurately meet specific orders with speed and with minimal human interaction.
If you are trying to get complicated rib orders filled via hand sorting, an automatic sortation system should definitely be a consideration.
Automated sorting and classifying systems have increased the productivity of many food plants and at the same time have helped reduce the number of repetitive motion injuries of workers. When problems with these systems occur, they are often in the following three areas:
- Sorting errors due to timing issues
- Lost production due to network failures
- Learning curves at start-up
1. Timing Issues: A sorting/classifier system needs to capture the weight of the item to be sorted and determine which bin, tote, box, or chute that item should be sent to. Sortation systems that depend on a pre-set amount of time to activate the proper divert are vulnerable to sorting errors due to timing issues. Sudden fluctuations in electrical power available to the system can cause considerable problems with sortation system timing.
Solution: Our approach is distance-based divert activation rather than time-based activation. By directly interfacing to conveyor movement and positively determining the amount of distance the item to be sorted travels, we eliminate sorting errors caused by electrical irregularities.
2. Network Failures: If your sortation system is remotely controlled via your computer network, you put your production at the risk of your network. When your network goes down, so does the sortation system.
Solution: We offer two types of controllers on our systems. Both of them can store a data base and both of them can continue to run in the event of a network failure. While the network is down, these controllers continue to store production records. When the network is restored, those saved records are available. The main differences between our two types of controllers are primarily in the type of data
3. Learning Curves at Start-up: As a company that has designed, manufactured, and supervised the installation of many sorting and classifier systems, there is an important personal aspect to automation that we have discovered. Your workers may need some time with our technicians during installation and at start-up. Many workers resist change, and this can apply to new equipment and processes as well.
Solution: To get the most out of your sortation system, be sure to schedule adequate time for our technicians to train the employees who will operate and maintain it.
If you are producing a random weight product and are packing them into a case that is being sold at a fixed weight, we can help maximize your efficiency and profit.
In this instance, we worked with a major cheese manufacturer that was producing 8 ounce bricks of cheese and packing them into 10 pound boxes. The system used to size the 8 ounce portions of cheese did not yield perfect results. Weights would range from 0.47 lbs (7.52 oz) to 0.53 lbs (8.48 oz).
The process they were using had the bricks of cheese going across the pricing scale and then being automatically labeled. The bricks would go off of the end of the scale onto a large round rotating table where several people would grab the bricks and fill boxes that were sitting on scales, and using trial and error, would swap out bricks until the box would reach 10 pounds. The people filling the boxes were supposed to use exactly 20 bricks and were to do their best to get as close to 10 pounds as possible.
This was labor intensive, fast-paced work that was very prone to human error. We were asked to see if we could come up with a more efficient way.
What we developed worked extremely well. We hooked into the existing pricing scale to send the weight for each package to our controller. Our controller was then able to track each package and how much it weighed through the new system.
With the new system, we set upa conveyor with 10 sorting stations, five on each side of the conveyor. As the bricks entered the system, the controller would make a decision based on each brick’s weight as to what station that brick would be sorted into. If that station’s weight was running light, it would get a brick that was heavier.
As each station’s box would get full, the controller would quit sending bricks to that station and turn on an indicator light to let the operator know that the box was full. At that time, the box could be slid forward onto another conveyor, and an empty box could be reinserted into that station. The operator would then press a reset button, and the controller would start filling that station again.
The system worked extremely well and only required one person on each side of the conveyor. The work was not nearly as fast-paced and the chance for human error was virtually eliminated.