When a consumer purchases a container of material, they want to be absolutely sure that the correct amount of material is actually in the container. When a manufacturer fills that container, they also want to be absolutely sure that they have filled the container properly. If they have not filled it with enough material, they are not providing properly for their customer, and may also be liable to legal penalties. If they have overfilled it, they are giving away material, and reducing, or perhaps even eliminating their profits. Furthermore, they must accomplish the filling task in as efficient and cost effective means as possible. All of these are perfect reasons to use an industrial scale to automatically fill the containers. Bench scales are usually suitable for filling containers with capacities from less than one pound, up to a capacity of more than 100 lb. The scale must have a platform size that is suitable for the type of container that is being filled. A typical 100 lb capacity bench scale offered by Arlyn Scales, utilizes a 12 x 16 stainless steel platform with a low 1 profile height. The low profile offers the advantage of easy loading and unloading of the containers. For appropriate automatic filling operations, the electronic scale must have the ability to be programmed for specific target weights. The front panel on the scale can allow the scale operator to input the desired weight of the filled container. Some filling device, such as a valve, solenoid, screw augur, or vibrating system, is activated to begin the filling operation. When the target weight is reached, the scale will switch off the electronic signal to the fill mechanism. The scale signal is usually connected to a solid state relay in order to control higher values of voltage and current. Even though the scale may very accurately sense the correctly filled weight, there will usually be some amount of overfill caused by the delay of shutting the filling device. If this amount is always constant, the programmed value can be decreased by exactly that amount. A more effective method is to employ more than one fill rate. The system can start with a fast fill mode. The first programmed weight value will change the fill to a slow fill, or trickle fill mode. The second programmed value can be the final desired fill weight. Of course, there can also be an intermediate fill rate, if desired. Arlyn Scales setpoint controller actually provides up to eight electronic outputs for a variety of different values. Often, an individual bench scale may be used to fill different container sizes, and different products at different times. A particularly useful feature is the ability to store a variety of different target weight values, and trickle feed or intermediate values, for more than one filling task. The digital scales noted above have enough on board memory to store more than one hundred different sets of target weights. Each set of target weights can be labeled with their associated product. When the scale operator moves on to another product, they have the ability to use a menu option to search for it by name or product number. The target weights can then be automatically implemented as the next filling operation begins. Yet another useful feature is the ability to capture the scale data during a period of time. One method to accomplish this is to connect the scale into a computer system. A variety of different communication capabilities may be employed, including the long term industry standard of RS-232, or one of the newer choices such as Universal Serial Bus (USB) or Ethernet. The data is stored in the computer in the form of a database table or spreadsheet. Reports can be formatted from this data for later analysis, or for entry into inventory control or accounting systems. Many operations, especially those that require the filling scales to be portable, do not have the ability to connect to a local computer system. In this case, a USB port on the scale can be filled with a flash memory device. Hundreds of thousands of data points may be stored, along with the time associated with that data. At any time desired, the USB memory can be removed from the scale and brought to a central computer. The data is downloaded from the flash memory into the spreadsheet or database as described above.
Copyright © 2007-2018 Circuits & Systems Inc. Arlyn Scales. All Rights Reserved.
