When sorting products, you need a part of the system to identify the precise position of each product on a conveyor belt. A common choice for this is distance-based encoding because it is generally an accurate and reliable method, resistant to any power outages or voltage drops that you might experience. It is a very sound concept, but there are actually several different methods that can be used to make it work.
One way to go about this process is by attaching a special wheel assembly to the conveyor. These encoders are free-rotating wheels that turn with the conveyor belt. When the belting moves and the wheel spins from friction with the belt, it can track the belt movement and send a digital signal which triggers the correct divert when the product should be reaching its intended location.
This can be a fairly stable method, but when paired with certain types of conveyor, especially low friction varieties, it can be difficult to make use of.
Some systems use special encoder disks which have small metal shards embedded in them at regular radial intervals. They are attached to a drive shaft of the conveyor, and a magnetic sensor reads the rotation of the disk because it picks up each shard as they rotate by. These can be purchased with a variety of precisions based on how many metal shards are embedded. Like the last, the system sends a signal to an appropriate divert once the encoder disk has reached the appropriate rotation.
The weakness of these is that the sensors can be damaged in rough environments, like those that require heavy washdown.
We decided to go with a simplified design similar to the last one. Our encoder is a disk with evenly-spaced, slotted holes around the perimeter. As it rotates, a sensor trips as each hole passes its beam. The distance between each hole represents a horizontal distance on the conveyor; this allows you to get products to the correct drop with accuracy every time, when properly calibrated. The simplified design makes it more reliable and less prone to outside damage.
We are experts in the field of sortation and other automation systems, as evidenced by our knowledge of traditional sorting methodology.
Some of you may be wondering: “What can I automatically sort, grade, or classify with the equipment that is out there today?”
With the type of equipment that we offer, we usually think of sorting by weight. We are capable of weighing anything and most of the time we can do it in motion. Today, even semis are capable of being weighed as they travel down the road at 70 MPH. In many places, items are being weighed and check-weighed by the gram and less. Once the user has a given weight, sorting is possible and can be done quite easily.
Now let’s add grading.
Grading is the term where we are adding another factor to sorting. Yes, you can grade by weight, but what if you need to grade by color or quality? Systems are being developed each and every day with an in-motion conveyor scale and a vision system that has the ability to grade and sort.
Vision systems have the ability to see color, to see the marbling in a piece of meat, to determine the thickness of the given object, and much more. Vision is being used to do Q.A. on just about every type of application there is.
When we sort and/or grade with vision, you need software that has specific parameters on which to measure what classification the product falls into. We then will know what needs to be done with the product being graded. If you enter the weight back into the equation, you have another set of parameters to work with. If you have done your set up properly, weight and grade will fall into specific classifications.
There is one other way of grading that is being done today in a number of applications, “human grading,” with the assistance of technology. Vision camera’s today have a tremendous amount of ability; however, they do not decipher information in the same manner as a human does. There are systems in place today where we have developed touchscreens giving the grader access to just touch an area on the touchscreen indicating a change in grade or an abnormality to the specific product area.
Add in a weight and now with proper software you have as many classifications as you need.
Although problems with grading, sorting, and classifying are infrequent, they do occur, as with all equipment. In some cases, the problem may be as simple as a loose or poor connection. This could be the case where keyboards are used for information input. The small wires sometimes are a bit fragile and break at connection points under the stress of continuous movements.
Obviously, when one is punching away at the keyboard nothing is appearing, there is a pretty good chance that either the keyboard or connection point is faulty. Moisture can often be the foe of the small input keypads, as well as the individual key contacts themselves failing from continuous and repetitive use. Thus, you should find it listed as a recommended spare part in such system.
Because timing and spacing are always important, an electronic device known as an encoder will sometimes be the recognized component experiencing failure. For example, in a hide sortation system, if the drops are continuously occurring at incorrect locations, the distance encoder is probably failing to do its job if other components are functioning properly. Components such as whip or trip switches as well as photo eye functionality can sometimes be the culprit.
Another area of suspect may be pneumatics incorporated in systems. Sometimes, air lines or pneumatic components require attention. Just like an electrical component, if the supply is not there, they may not function or will do so improperly. With this in mind, it is important to perform preventative maintenance and operational checks on a routine basis.
Not all problems are the result of equipment failure. Functionality failure can sometimes be the result of operator errors rather than equipment failure. Where redundancy is a fact of operations, people sometimes react or see things incorrectly. For this reason, people commonly cycle through these positions on a scheduled basis. When this doesn’t happen, problems can arise, and wrong buttons are pushed.
In high quality systems, although problems occur rarely, they are frequently simple to identify and relatively easy to correct. Serviceability and support are important ingredients that we have available for your consideration.
When designing sortation systems, there are many decisions to make and options to choose that effect the system’s performance. Most of the options that are available with a sortation system are pre-defined by the product that the system will be using.
One of the options that differs most between sortation systems is the divert. There are many types of diverts that can be used to sort, but that doesn’t necessarily mean that they are all good at the same type of sorting. Having the wrong divert could mean product damage, or it could cause your sortation system to malfunction in some manner.
Here are some of the most common pairings for a handful of commonplace divert styles.
Pull-off- This style uses a pneumatic arm to catch products and pull them towards their location. This is often associated with products that are sticky.
Push-off- Uses a pneumatic arm like the pull-off but uses the same motion to push instead of pull. Used for non-difficult, well-formed products. Faster compared to the pull-off, but doesn’t handle the same products.
Also used for heavy products in tandem with roller conveyors. Regular conveyor belting doesn’t hold up well when a heavy weight (i.e. >100-lbs) is pushed against it.
Linear thrust- pushes product directly off of the belt with a pneumatic cylinder. Usually used with packaged products because they slide off of the conveyor easier.
Air thrust- same concept as the linear thrust, but uses a blast of air to move product instead of a physical cylinder. Ideal for lighter packaged products.
Drop-down- A section of conveyor lowers to a belt or bin below, allowing product to slip underneath. This can be used for sortation systems that feed other conveyors or for products that have to stay upright.
Note that these guidelines for diverts are not set in stone, because there are so many things that need to be taken into consideration before a sortation system’s final design. Sounds daunting, doesn’t it?
That’s where we come in. Don’t fret, about upgrading your plant because it is our goal to provide you with the best sortation systems on the market. We specifically design each sortation system to fit seamlessly into your operation. Request a quote and let us know what you need so we can work with you to find a custom sorting solution!
Let’s say you’ve made the decision to automate the sorting of the products or raw materials in your plant.
You are making a major step forward in efficiency and productivity over costly and inefficient manual sorting or grading.
When it comes to deciding how many drops to specify in your automatic sortation system, it may not be as simple as counting the number of grades or the number of products you want sorted.
You may be far better off if you take that number and double it.
The result will be more throughput and lower labor costs.
With duplicate divert parameters, or paired drops, you will not have to stop your line when a bin, box, or combo gets filled to capacity.
Nor will you have to assign an employee to hover over those drops in an attempt to immediately pull out a filled receptacle and replace it with an empty one.
When you duplicate your divert parameters between two stations, you will reap the benefits of continuous sorting regardless of the fill status.
There will be some additional upfront cost, but the increased production rates and lower labor costs will provide a payback for many years down the road.
With years of designing and building grading, sorting, classifying systems we make sure our customers make informed decisions so they get a system that will give them the best possible return on their investment.