The following is an overview of different types of small digital scales, listed approximately from highest to lowest resolution.

• High resolution scales

These types of scales are suited for laboratory use in universities.  Ideally, they should include a tare function for zeroing weighing vessels such as weighing paper or trays.  A standard feature is display capability for different weighing units, most commonly, ounces and grams.  The desired resolution for these scales is 1 mg, a requirement met by scales with maximum weighing capacities of 750 mg.  For pharmaceutical applications, the resolution should be 0.1 mg.

• Counting scales

Counting scales are useful for measuring quantities of items whose weights are consistent.  They often have a memory feature that stores the weight of as much as 450 different items, which eliminates the need to weigh a standard sample every time.  Fulfillment centers  use these scales for counting products quickly and accurately. Document control and business card supply companies often use them to count sheet paper and business cards. Utilizing counting scales for fulfillment purposes is advantageous to a business because it reduces quantity errors on product orders, which leads to greater client satisfaction.

• Rain gauge scales

The scale method of measuring precipitation is superior to standard graduated rain gauges in that the weight, rather than the volume of precipitation is measured.  This confers greater accuracy, since water tends to stick to the sides of standard rain gauges, resulting in under-estimates of actual precipitation.  Another advantage of using rain gauge scales is the option of using a meter that measures the amount of chemicals present in the precipitation, for the purposes of quantifying environmental pollutants.  These scales must be resistant to moisture, corrosion and extremes in temperature.

• Industrial bench scales

Bench scales have a display that is attached to the weighing platform by an electronic cord, and can be interfaced with a computer for advanced computing features and functions, including displaying and recording weight data.  A label, paper, and card printer may also be attached.  They are used in postal services, shipping and receiving centers, as well as the food and restaurant industry.

The weight values that are shown on the indicator of an industrial scale are of critical importance to the scale operator. A bench scale may be weighing small packages. Or a parts counting scale may be determining the number of parts in a container. Larger drum scales and platform scales may be determining the amount of liquid in a tank or dewar or drum. And large floor scales will be weighing totes, pallets and large tanks. Besides reading the weight information, the operator of the electronic scale can also perform certain control functions, such as applying a tare weight, zeroing the weight on the scale, and choosing the units of measurement, such as pounds or kilos.

While it is required and expected that all digital scales provide all of this functionality locally, it is often desired to be able to also perform all of these functions from another location. In these cases, the most common requirement is to read weight data and control the scale from a local computer. Arlyn Scales provides optional Remote Indicator software that can be operated from any Windows based computer. The electronic scale must be connected to the computer. Typically, this connection would be an industrial standard RS-232 communication line. Alternatively, the USB (Universal Serial Bus) connection may be used.

Now, the computer operator can read weight data directly on the computer screen. They can also save this data in some other computer format, including spreadsheets and databases. Furthermore, the industrial scale can also be controlled directly from the computer. If the scale must be switched from the Net mode to the Gross mode, or the weight of a container must be subtracted, this may be accomplished from the computer keyboard.

An industrial scale is a wonderful instrument for determining the weight of an item. Bench scales accurately weigh small items. Depending on the capacity of the digital scale, the readability of the weight can be as small as 0.0001 lb. Platform scales weigh larger packages and drums up to 1000 lb, whereas floor scales and pallet scales can accepts loads up to 20,000 lb. The accuracy of the electronic scale is dependent on the type of technology used. High quality industrial strain gage scales have an accuracy range of approximately 1/10 of 1%. If greater accuracy is required, alternate ultra precision scales, such as Arlyn Scales Surface Acoustic Wave technology can provide ten or even twenty times better accuracy.

But even an industrial scale with the best accuracy obtainable will not be of value within an industrial process if the user chooses not to use it because it is too difficult. Even if the electronic scale is being used, if the reading cannot be easily read, it is likely that inaccurate results will be obtained. Gross errors will occur if the front panel controls are confusing, potentially resulting in readings of kilograms where pounds are expected.

Good design practices can combine ease of use with excellent accuracy. For example, Arlyn Scales provides a combination of clearly marked front panel controls with a graphics, menu driven digital display. The user is guided through weighing operations by menu prompts which automatically scroll to the next operation. Furthermore, the very low profile of the industrial scales assist the scale operator in placing objects onto and off of the industrial scale platform. High quality stainless steel load cells protect the scale from damage caused by dropping items onto the scale platform, in addition to providing many years of trouble free use.

Parts counting scales are an ideal tool to use for counting parts that are identical in weight. Items such as bolts, screws, nuts, rivets, washers and other fasteners would fit this criteria. Similarly, electrical contacts, connectors, resistors, diodes, and integrated circuits would also be suitable. The scale operator places a small sample of parts on the digital scale platform, and through the keyboard, enters the number of parts in the sample. The industrial scale then calculates the weight of a single part. At this point, as parts are added onto the platform, the electronic scale can divide the total weight by the piece weight of the part to determine the total number of parts.

The accuracy of a parts counting scale is highly dependent on the accuracy of determining the piece weight during the sampling process. Arlyn Scales provides very high resolution for their digital scales in order to enhance this process. But for very small parts that must be counted in great quantity, the scale must have even higher sampling accuracy. Arlyn Scales Ultra Precision scales are ideal for this purpose. They provide twenty times the accuracy of standard parts counting scales.

For heavier parts, such as assemblies, castings, and enclosures, parts counting capability can be added to larger capacity scales. These include platform scales and floor scales. In some cases, as smaller bench scale is used for the sampling process.

Other industrial scale features can also be included in the parts counting scale. These can allow parts data to be communicated to a computer, or collected in a USB memory stick. It can also be sent directly to a local printer to provide adhesive labels.

Counting parts by weight is an efficient means of determining inventory levels. Any item that is consistent in weight may be counted by a parts counting scale. These items can include standard industrial hardware, such as fasteners, washers and clips. Electronic devices are another perfect item to count by weight.

A good parts counting scale must have two primary features. It must have enough capacity to accept the full containers of parts. And it must be sensitive enough to accurately determine the weight of just a few sample parts. These two characteristics are often mutually exclusive. As a rule, the higher the capacity of the scale, the lower the sensitivity.

The accuracy of the weight of the sample parts is the largest factor in determining the accuracy of the parts counting results. As the samples may only represent one percent of the capacity of the scale, or even less, the scale sensitivity should be one hundred times greater than that. Very few industrial scales can meet this requirement. But the precision scales offered by Arlyn Scales in their SAW family provide sensitivity of greater than one part in one hundred thousand. For example, a SAW counting scale with a capacity of 100 lb has a display sensitivity of 0.01 lb with even greater internal sensitivity. This is twenty times higher than the readability of standard strain gage industrial scales. For counting small pieces, this will result in an accuracy level that is twenty times greater.

Often, high sensitivity and accuracy indicates that the precision scale may be delicate, and prone to damage during use. The SAW ultra precision scales provide overload capacity of more than four times the rated capacity of the scale. Most other industrial scales only offer an overload specification of one and a half times rated capacity. Therefore, the precision scale does not need any kind of special handling to produce very accurate results.