When you need to keep an inventory of small pieces or parts using a counting scale can make the process run much more smoothly. Yet it’s important to be careful. Inaccuracies arise most often when acquiring the weight of the sample piece or pieces. If this happens, your inventory can be significantly off.
Off By How Much?
Let’s say you have a regular scale with a 100 pound capacity and a resolution of 0.02 lb. If your sample weight is .03121 lb and the size of your sample is 10 pieces, the result is .3121 lb. However, your scale is only able to read to its best resolution, which is .32 lb. The error is 2.5%. That’s pretty significant.
How Arlyn Reduces the Error
Now, with a SAW-C scale from Arlyn Scales, you have the same 100 pound capacity, but your resolution is much finer at 0.001 lb. If we use the same sample weight (.03121 lb) and sample size (10 pieces), the scale will read .312 lb. The error is reduced to .03%, which is much, much better.
Perfecting the Counting Scale
So what makes our SAW-C scale better than your standard counting scale? It has to do with out internationally patented surface acoustic wave (SAW) technology, which replaces the strain gage system your scale most likely has.
The Trouble with Strain Gage
A load cell is a type of resistor that features an aluminum or steel spring element that is attached to the underside of a scale’s platform at one end and the base of the scale at the other. Affixed to the flexures of this spring element are four strain gages, which are wired together to form a Wheatstone’s bridge. The spring element bends when weight is applied to the platform. How far it bends is directly proportional to the weight applied to the platform.
So when the spring element bends, the flexures do, too, causing a change in the resistance of the gages. This change in resistance also changes the voltage output of the bridge. The voltage is then passed through an analog-to-digital converter and sent to the digital display where the weight can be read numerically.
However, the adhesive used to place the spring inside the scale can have an adverse affect on the accuracy of the measurements taken. The spring has a tensile quality that the adhesive lacks, which affects the flexibility of the spring and therefore its ability to generate an accurate, high-resolution measurement.
As with most resistors, strain gages are also affected by changes in temperature, which means that fluctuations in temperature can also affect your accuracy. They’re also subject to deformation from shock and overloading Ð two major causes of scale failure.
SAW Technology from Arlyn Scales
Our SAW model scales are distinguished by their precise, high-resolution measurements and durability in tough industrial environments. Instead of measuring the strain placed on the spring element, these scales measure displacement using two Surface Acoustic Wave, or SAW transducers.
This means measurements are inherently more accurate because the strain levels are less than 10% of those found in strain gage scales. It also means that the scales are more durable and more reliable because they have a higher overload capacity.Because of this, they are much more resistant to shock load and overload, which are, as mentioned, two of the most significant causes of scale failure.
Using a similar theory of load cell design, our ultra precision SAW scales still feature of a spring element. But that’s where the similarities end. The substrate material of our SAW transducers is a crystalline structure composed of lithium niobate. A bulk wave is created by a metalized pattern that acts as a transmitter and is sent through the substrate. The wave travels the length of the transducer and generates and equivalent signal on a second, parallel substrate.
A second metallized pattern on the second substrate acts as a receiver. The distance between the transmitter and receiver and the frequency of the wave’s oscillation between them determines the displacement of the spring element, which is measured digitally, making the SAW scales inherently more accurate.
While regular scales generally have a readability of 1 part in 5,000, our ultra precision SAW scales have a readability of 1 part in 100,000 Ð a resolution that is twenty times higher than that of a strain gage scale. This is why our counting scales have significantly reduced margin of error.
Quick Count Feature
Our counting scales also come equipped with our unique Quick Counting feature that allows you to easily count parts without all the confusing menus found on competitor scales. And once you sample a part, you can store the piece weight for future use; these scales will hold as many as 100 different piece weights! So once you’ve sampled a product, you’ll be able to bypass the sampling process in all future inventory counts.
You can also use the accumulation function to keep a running count of a large inventory that may be stored in several containers or will not fit into one weighing cycle.
Inventory data is meant to be shared, which is why we offer a variety of communication options including USB, flash drive, Wi-Fi, Cloud, Ethernet, RS-232 and more.
Factory Direct Pricing
Because we’re a factory direct manufacturer, there are no price mark ups due to distributor or import costs. We manufacture our scales and their subassemblies right here in our New York factory. This means you get a higher quality product at an extremely competitive price.
This also means we have the ability to provide custom weighing solutions. Whether you need a particular platform size, data communication option or other feature, we can work with your specs and provide a custom scale that meets all your needs.
You Can Count on Arlyn Scales!
If you have questions about our counting scales or would like help with the selection process, contact us today. We can supply you with additional information or help you narrow down your options so you make the best possible choice.