If the printer/applicator is holding things up, there is generally a couple of things to look into. The first and most important is label length, you need to be sure that the label is as short as possible so that the label is out of the print engine and ready to be applied when the box arrives. The other possibility is the speed that the label is fed out of the printer. 6-6.5 inches per second is usually as fast as you would want to go before the quality of the printing starts to suffer to the point that you will be getting no reads on the bar codes. The speed can sometimes be pushed to seven or seven and a half, but the printer will need to be kept extremely clean, especially print heads and print rollers, and the label stock will have to be of a high quality.
If the In-motion conveyor scale is causing the bottleneck you will have to be sure that the scale system was properly engineered to give you the best possible results for the size of your box and desired throughput. We take many factors into consideration when designing a box labeling system. What is the length of the boxes to be weighed? Will the boxes all be of uniform length? Or will the length vary? What is the weight range of the boxes? And of course, how many boxes per minute need to go through the system?
We recently were able to help a large company increase throughput on their box labeling system by going to work and re-engineering the scale section of their system. They were weighing and labeling a very large and heavy box. We were able to reduce the length of the scale by 25% and this allowed for nearly 25% more throughput because just prior to a box leaving the scale the weighing process is complete and the next box can begin entering the scale at this time.
You might ask, “Why not just use a very short scale?” And the answer is “because you will not get accurate weights!” The reason for this is when a package first enters the weighing platform it jars or shocks the scale and the weights fluctuate up or down. So we design systems that the weighing platform is of adequate for the weight to stabilize and gather accurate in motion weights before the end of the scale.
In conclusion, you can see that scale length is an important consideration to get the most throughput out of your system. Keep in mind that if you have a heavier package or too much belt speed the shock or jarring to the scale will be greater and it may not have time to settle down before the end of the scale.
We helped a customer increase production by nearly 10% on one line, by simply adding a second labeler to their system. This was a high speed system that was labeling at over 130 packages a minute. The label rolls that they were using contained 3,000 labels. This meant that the label roll would run empty in less than 24 minutes.
Obviously this line would be shut down while the label roll was being changed out, however, this company had a very good operator working on this line and she could change the label roll out in just over 2 minutes.
We set up a second labeler that was paired to the first labeler so that when the first labeler ran out of labels the second one would automatically take over the labeling this immediately took production from 7,150 packages per hour to 7,800 packs an hour.
The customer also found some other benefits as time went on. They found that production didn’t suffer as much when the normal operator was gone, because the fill in operators were not as fast as she was at changing out the labels.
Whoever was filling in could easily take twice as long to change out the empty roll causing twice as much down time. They found that without the necessity to change out the labels so fast, that the operator could take the time to do the proper maintenance on the machine like cleaning the print roller and print head after every label change, as a result the read rates on the bar
Another benefit was realized when they would change to a product that would require a different label, they could set up the labeler that was not being used at the end of the first run to produce for the second run. That way when the next run started they could switch over seamlessly with the push of a button.
Additionally they were better equipped when their customer asked that a second label be applied for a special that the store was running. T
hey now have some peace of mind knowing that if one of the printers has a problem the other one can continue to get the days production out the door.
A good example of this is a plant that packages and distributes offal products. They tend to have a lower volume of product to work with, but it is highly varied. They have to be ready to run special orders. This means that they could be filling up something like a small box or something as large as a combo.
With all of these different order possibilities, these plants need a good way to label each one accurately. For this level of product volume, a manual labeling system can do wonders.
A manual labeler can be linked to bench and deck scales to accommodate varying package sizes. Typically, an order comes through, operators pack the proper offal into an appropriately sized container.
At a manual labeling station, the operators weigh the container. This could be simply placing the box on a bench scale, or it may require someone to haul a combo onto a deck scale with a forklift. Either way, the operator then enters in a product code which contains all of the necessary information.
There are many ways to do this. The operator can manually enter the code. He might have a scanner to scan pre-identification labels on the packages, or he might have a pick list of sample barcodes nearby that he can scan based off of the product and package size.
However identification is done, the labeler then calculates all of the appropriate weight info (including the tare weight for the container) and product ID and prints out a label to be hand applied to the box or combo.
This is an especially nice system when palletizing boxes because it can automatically produce pallet manifests which have serial numbers and weights of all products on the pallet. This helps greatly with data management and is an important step to traceability.
If you are looking for a sensible way to label, a manual box labeler could be a good way to go, but we can help you in designing a system that fits your needs specifically.
Repeatability, Accuracy and Division size can be very confusing when trying to evaluate performance of an in-motion checkweigher. Unfortunately many in-motion checkweigher suppliers attempt to confuse the perspective purchaser rather than inform and educate.
For the sake of this article, let’s assume we have a 2 kg in motion checkweigher that has a division size of 1 gram and will use a test puck that weighs exactly 522.00 grams. Let’s examine each term:
Repeatability is the ability of checkweigher to show the same result over and over using the same test item (test puck).
Perfect repeatability would mean that every single in-motion (dynamic) weighment of the single test puck returned exactly the same result. Thus, if this particular test puck that weighed 522 grams were weighed 100 times, every single weighment would be exactly 522 grams. While this is possible, it’s somewhat unlikely depending on the division size, pieces per min, and speed of the belt.
Repeatability is often referred to as +/- X number of division. Perfect results is this example would be +/- 0 d (described below, see “scale division size”).
Accuracy is really not a proper term in the field of weighing, as it is not defined in NIST (National Institute of Standards and Technology, Handbook 44 (scale man’s bible)); However, accurate is defined there and is more of a pass fail determination rather than a method to measure performance.
Accurate as found in H44 is defined below:
Accurate – A piece of equipment is “accurate” when it’s performance or value – that is, its indications, its deliveries, its recorded representations, or its capacity or actual value, etc., as determined by tests made with suitable standards. If this criteria conforms to the standard within the applicable tolerances and other performance requirements, the equipment is deemed accurate.
Equipment that fails to conform is “inaccurate”.
A scale, in-motion checkweigher, automatic weighing system, conveyor scale, etc. is accurate if the device is able to meet a prescribed tolerance.
For instance, our example in-motion checkweigher above has a maintenance tolerance of +/- 2 divisions between 501-2000 divisions taken from the NIST handbook 44 automatic weighing systems section.
The checkweigher is accurate if weighments fall between 520 and 524 grams if the division size is 1 gram. The same scale would have to have all it’s weighments fall between 521.8 and 522.2 if the division size was 0.1 grams, to be considered accurate.
Since the test puck is so close to the tolerance level of 0-500d, we suggest using +/- 1 division tolerance to measure performance.
Scale division size, (commonly know as “d” in the weighing industry), is defined in NIST Handbook 44 (H44) as: Scale Division, value of (d).
The value of the scale division, expressed in units of mass, is the smallest subdivision of the scale for analog indication, or the difference between two consecutively indicated or printed values for digital indication or printing.
Since most modern weighing equipment is digital, it is really the amount that the checkweigher counts or displays by.
For example, our 2KG capacity checkweigher may have a division size of 1 gram. Thus, the division size is 2 thousandths of the check weigher’s capacity (2,000 divisions).
Unscrupulous manufactures and representative will often try to mislead a potential purchaser by trying to confuse the purchaser by claiming division size is accuracy. This is a lie! A deceptive supplier may configure a checkweigher that had perfect repeatability and be accurate and at 2,000 divisions instead at 20,000 divisions at 0.1 grams!
It’s not surprising that the repeatability turns bad in a hurry and the device will not be able to meet tolerances and is thus classified as inaccurate. Instead of reliable weighments that the purchaser can count upon to manage their business, the purchaser is left with endless garbled weighments and performance tests that are not only inaccurate but also very confusing.
Know your in-motion checkweigher, automatic weighing system, or conveyor scale terminology. Ask for repeatability specifications for a given division size just under the tolerance break points: 0-500d, 501-2000, 2001-4000, and 4001-up.
Never believe anyone who says accuracy is division size. Use NIST H44 tolerances as your guide to determine value and performance capabilities!
In Motion Checkweighers are an important part of many industries
Just think about it: how many of the items you buy in the grocery store have weights marked on them? Just about every food item, many pharmaceutical items, personal hygiene items, the list could go on and on.
Now think about how those products can be weighed. The most common way most people would think of is static weighing. In order to weigh statically, whatever is being weighed is physically placed on the scale and physically removed. A good example of static weighing would be your normal bathroom scale or the scale the meat counter at the grocery store uses to measure out the meat from the meat case.
Static weighing works well, but what if you had to weigh thousands of products each day? There would have to be a more efficient way to do that, wouldn’t there? There is a more efficient way and that is in-motion weighing! In-motion weighing weighs those products while they are moving so they don’t have to be manually placed on a scale and manually removed from the scale.
Weighing products while they are in motion can greatly increase the amount of product that flows through the plant each day.
No more repetitive manual labor is needed to weigh it and in-motion weighing can be very accurate when done properly.
In addition to just taking weights, an in-motion scale can perform many other important functions including weight reporting, checkweighing, and sorting. But that is a topic for another time.
Next time you’re looking to weigh your product and need to move a lot of product while still weighing it, consider an in-motion weighing system. You won’t regret it!