Know Your Load Cells

Every electronic weighing systems contains load cells.  Below is a short primer about load cells and how they operate.  By the time you finished up this read, you will be friends with the terminology and have a feel for the  functioning of load cells.

System Components:

Weighing systems are utilized in both static and dynamic settings. A few cutting-edge advanced  systems can actually interact with computers for database integration, and then utilize this inputted  readout to determine proper flow or feed rates/proportion of materials to be added to a mix(ture). 

Once the analog signal is converted into a digital form, the load cell will directly and speedily analyze weight information. 

A total system can be pieced together from basic modules, one component at a time.

The ABCs:

One kind of  force transducer is called a load cell.  This cell is capable of converting force or weight into an electrical signal.  Its nucleus is referred to as a strain gage.

The strain gage acts much as a nerve does in your body, changing resistance when subjected to stress.  Gages are made from extremely-thin, heat-toughened metallic foils bonded to a thin dielectric layer.  These "gage patches" are  then attached to the strain gage with special bonding adhesives. The exact positioning of the gage, the mounting procedure, and the materials used to construct the load cell all have a significant effect on overall performance of the load cell.

Each gage patch is put together with one or more very fine wires glued to the surface of a beam, ring, or column (the strain element) within a load cell. When the surface to which the gage is latched becomes stressed, the wires stretch or contract changing their resistance proportional to the applied load. Eac load cell is made up of one or more strain gages.

Multiple strain gages are connected to create the four legs of a Wheatstone-bridge configuration. When an input voltage reaches the bridge, output becomes a voltage in proportion to the force on the cell. This output can be amplified and processed by conventional electrical instrumentation.

Figure - An Unbalanced Wheatstone Bridge