Counting Scales
Manually counting parts or small items leads to human error. By using special scales designed for counting parts, a company can eliminate this human error and a therefore eliminate some labor cost. These scales called counting scales are used to count small items or parts quickly and efficiently by weight. This scale quickly converts weight information into piece count information and vice versa.
Digital counting scales look at the weight of the items you have placed on the weighing platform and divide the weight by the number of pieces you entered to compute the average piece weight. Usually, the person operating the scales will hand count a sample of the pieces he/she wants to calculate. After zeroing out the unwanted weight for any container, he/she places this sample on the scale and enters the number of pieces in the sample. The scale divides the weight on the scale by the number of pieces on the scale to determine the average piece weight, or APW, of the piece. Then the scale can apply this APW to the total weight and display the count. Just as a scale can be calibrated to weigh in pounds or grams, a counting scale can be calibrated to weigh in units of a specific piece. The items being counted must all have equal weights for the scales to operate correctly. Of course, the more of the items there are, the more accurate the scale can be with its results since it will average out any variations to all the pieces.
Counting scales have different levels of capacity. Some scales can count pieces with tens of pounds of weight and some only have a capacity of a few grams. It is important to not purchase a counting scale with too much capacity than your needs. In order to have a larger capacity, you will be sacrificing resolution. Do not be fooled into getting a larger capacity thinking you “might” need it in the future. If you think there might be a possibility that you will need to be able to count things above the capacity of your counting scale, make sure your scale has a remote scale option. This means you will be able to attach a larger scale to your mechanism for counting items of a heavier weight.
There is some error involved with using counting scales, but certainly less than would be had with manual counting. There can be operator error such as forgetting to zero out the container weight or miscounting the sample. There can be piece weight error. This happens when the operator does not take a large enough sample to average out the variations in weight equally. Piece weight error can also occur when the scale is not level or if a draft or open window affects its accuracy. Some error is from scale related issues. These issues usually have to do with the scales settings. Counting scales can be set to certain resolutions. After millions of counts, a scale will start to not accurately weigh the sample, which throws the entire count off. Setting the scale to tolerate some errors can alleviate this. Usually allowing 2% is a good idea to keep the scale accurate.