Instruments that are used to obtain the accurate weight of items have been used in many different types of industrial applications. These industrial scales are designed with a variety of characteristics to match the use for which they are intended. Even the format of the electronic scale will vary to match the weighing job required. Large floor scales will accept heavy loads, such as pallets, totes, tanks or dewars. They are often loaded with forklifts or other power equipment. Drum scales may be used to monitor the contents of a liquid material that is being dispensed as part of an industrial process. Platform scales perform many different tasks, such as weighing incoming and outgoing shipments. Smaller parts counting scales are useful for accurately determining the number of pieces of an item in a container. They may be used for packaging parts for sale, or even for taking inventory. Bench scales are useful for mixing a variety of ingredients in formulating products, or just for weighing smaller packages for shipping. Although the many different types of digital scales have many different characteristics, they also share common attributes. All scales must have components that detect weight and convert that weight into an electrical format. These are known as transducers. The most common type of weight transducer for industrial scales is a strain gage load cell. This consists of a spring element which is generally a piece of metal that has been machined to a particular shape. Strain gages are bonded to the spring element to provide a changing electrical signal that is proportional to the amount of bending that occurs. Electronic components convert the changing electrical signal to a digital format. The load cell is often made from aluminum. Another alternative is alloy steel that is plated with nickel. The best type of material is a stainless steel alloy, such as that used by Arlyn Scales.
For higher precision levels, a force motor transducer may be used. This device utilizes the principal of an electromagnet to accurately offset the weight placed on the scale. Although it is much more accurate, it is also much more expensive. So it is only used in certain specialty industrial applications. Arlyn Scales has introduced their Ultra Precision Surface Acoustic Wave transducers. These provide the same, or better accuracy as the force motor transducer. But the cost is only slightly higher than strain gage transducers.
Whichever transducer is used by the industrial scale to obtain weight values in a digital format, the data must still be presented to the user in a format that is easy to read, easy to use, and easy to record. Simple digital scales employ a numeric display to show the weight. There are usually an indication to represent the unit of measurement that has been selected, such as pounds, kilograms, ounces or grams. There may be another indication to show that a tare weight has been subtracted from the total weight, or alternatively, that the weight shown is the actual gross weight. Three or four push buttons on the front panel are used to turn the scale on and off, select the unit of measurement, and apply a tare weight. While this type of scale is very simple, it can often introduce operator error. It may not be very clear if a tare weight value has been subtracted. It can also be easy to confuse the measurement unit. Furthermore, there are only a limited number of features that may be accessed. For example, there may be no parts counting features.
More sophisticated digital scales may use a specially designed display. Units of measurement may be fully noted, and will appear whenever they are activated. Similarly, gross and net weight legends can also be available. In addition to the numeric weight display, there may be additional, smaller numeric panels which may be used to show piece weight or the number of parts during a parts counting operation. The front panel can include dozens of buttons to access all of the features. A full numeric keypad enhances the ease of entry of tare values and piece weight information. Unfortunately, all of the additional features add significant complexity to the user interface. It becomes difficult to learn how to operate the scale, and how to easily obtain the desired information without being distracted by extraneous information.
A color touch screen panel user interface combines the advantages of simplicity of use along with sophisticated advance features. Arlyn Scales provides a large high resolution screen on these models of their industrial scales. Only the information currently required by the user is shown on the display. Therefore, the digits and legends can be large and easy to read. Only those buttons that are necessary for the current mode of operation are shown on the screen. The operator can easily choose the actions that may be needed. When a different function is chosen, the screen changes to display different information and a different selection of buttons. The high brightness screen can also be seen in all ambient lighting conditions, making it ideal for industrial use.