Weighing products in a factory or commercial setting can be a time-consuming process. You have to stop the line, take a product off of the conveyor belt, weigh it, and put it back.
This can interrupt the flow of production and cause delays. But what if there was a way to weigh products while they were in motion?
That’s where dynamic weighing scales come in. At Arlyn Scales, we’ve been operating dynamic scales for decades. In this article, our expert metrologists take a look at their advantages and applications.
What is Dynamic Weighing?
Scales are used to measure weight. Pretty obvious, right?
Well, when an item is placed on the scale platform, it causes a weight transducer inside of the scale to respond to that weight with an electrical signal. This signal travels to a weighing scale indicator (or is sent electronically to some other control system) to be displayed and converted into useful information.
Usually, this process takes place at a pace that is suitable for your operators. Sometimes, though, it must proceed at higher speeds. Whether this process occurs during production, loading, or transport, these operations require a suitable dynamic scale.
What is a Dynamic Weighing Scale?
A dynamic weighing scale measures weight while the items are in motion, such as while the products are loaded to the carrier. This provides real-time feedback on a product’s weight, rapidly & efficiently, to maximizes the accuracy and consistency of your production line.
In a typical production line, there may be a requirement to weigh each item that comes down the line. You may use a platform scale or a bench scale for this purpose, as even a weighing system as simple as a conveyor scale can accomplish this.
However, the number of items that your operators can weigh each second is limited by the specifications of the scale itself. Many scales require two or three seconds for each reading, while a few may only require one second per reading.
What if Pausing Your Production for this Process is Prohibitive?
If a motorized conveyor is running at high speed, the items may be moving over the platform very quickly.
A specialized scale may be needed to accurately weigh each item separately.
This is known as a dynamic weighing scale.
Components of a Dynamic Weighing System
There are three major components in a dynamic weighing system. The body of the scale includes a frame, which houses the internal components, and a platform.
The platform can support a conveyor mechanism, which may be conveyor rollers, or ball rollers, or any type of belt system. The weight transducer, or load cell, is rigidly mounted, on one side, to the frame of the scale, and on the other side, to the platform.
Many load cells use strain gauge technology. Some high performance units utilize ultra-precision Surface Acoustic Wave load cells.
The Electronic Section Receives the Output from the Load Cell
It translates that output into a value that can be shown on a weight display.
Alternatively, it can be formatted into a wide variety of different communication formats and transmitted to a control system.
Different formats include RS-232, USB, Ethernet, and WiFi. Modbus is also available on some models.
Industry Uses for Dynamic Weighing Solutions
Whenever we think of big industry, we envision speeding conveyor lines with boxes flying down them.
However, in reality, the conveyors may not be speeding very fast, and they may not be carrying cartons at all.
The items being weighed can range from tiny to tremendous.
Agricultural Applications for Dynamic Scales
Food products often have weight variations. One watermelon will weigh a different amount from another. There are similar differences between bunches of grapes, or fish or meat servings.
A particular range of weight will allow the food item to fall within a particular classification.
The sorting of classifications by weight may happen manually. The conveyor speed will be matched to the ability of a human to pick out the item that does not meet the classification.
While the scale must be able to weigh dynamically, you may only need the scale to take two or three readings per second. In that case, a suitable bench scale can be programmed to measure weight at that rate.
Manufacturing Applications for Dynamic Weighing Scales
Assemblies are prevalent throughout industry. A door on a vehicle may require 50 or more different parts, ranging from insulation panels to small rubber “O” rings, which could all be packaged together. A single missing piece could cause a slowdown on the assembly line.
Thousands of these assemblies may be kitted together by the supplier. They may be check-weighed on a conveyor line to confirm that there are no missing pieces. In this case, the entire kit may weigh 40 kg, but the smallest part may weigh only 2 grams. The scale will need to have a large capacity and also have excellent sensitivity.
Regular dynamic scales do not have that capability.
Instead, Ultra Precision SAW scales are available with a capacity of 45 kg and sensitivity of 0.5 g. They can also be programmed to read up to 30 times per second, making them suitable for this type of application. Furthermore, they are very rugged, and can accept the types of forces that may be experienced on a conveyor line.
Pharmaceutical Applications for Dynamic Weighing Systems
Few things are as critical as finding the correct weight in a medicinal or other pharmaceutical product. The tolerances could be very tight, and the overall weight of a finished package could be reasonably high.
This combination presents a real challenge for standard dynamic weighing.
If we take an example of a carton of pills, the finished package weight could be 3 kg, or even more. Having just a single extra individual pill would not be acceptable, so the weight tolerance for this carton could be just a small fraction of a gram.
This would be completely outside of the capability of standard equipment.
Using similar technology to the Ultra Precision scales noted above, a premium SAW scale can achieve extreme sensitivity of 0.02 g, or 20 milligrams. The weight capacity is as high as 4.5 kg. A wide variety of optional communication outputs allow data to be sent to a control system.
Build Your Dynamic Weighing Solution with Arlyn Scales
A high-speed weighing system can be a vital part of any production line. In fact, unique technology like this may be the only way to achieve your specifications.
The engineering team at Arlyn Scales has both the expertise and the access to this technology, and they welcome challenges. They’re prepared and waiting to provide the results that you need.
Furthermore, our representatives can answer any and all of your questions. To discover how to improve your operations with a dynamic weighing system, reach out to our team today.