Load cells are a type of transducer that determine the level of force applied to them and output this information as an electrical signal.
The majority of load cells measure force using a strain gauge, though versions using pneumatic or hydraulic systems are also available.
Strain Gauge Load Cells
Load cells that use strain gauges usually consist of four strain gauges laid in a Wheatstone bridge configuration – an electrical circuit configuration with two balanced bridge circuit components.
The applied force (to be measured) deforms the strain gauge itself and the extent of the deformation determines the size of an electrical signal generated, thus providing a means of measuring the force.
Several different types of strain gauge load cells are available; including gauge configurations such as s-type, shear beam and compression.
U2A Compression and Tension Load Cells. Image credit: Hottinger Baldwin Messtechnik GmbH
How Do Compression Load Cells Work?
Compression load cells can be considered as a block, which holds a load at one point and measures the extent of compression. This means that they measure the force pushing into them in one direction; this is in contrast to tension cells, which measure a pulling force. In most cases, the object to be measured is placed on top of the compression cell.
As discussed earlier, compression load cells use the deformation of the strain gauge (in response to the applied load) as a means of determining the force applied. Determining the relative differences in electronic resistance produces the electrical signal.
Using a Wheatstone bridge configuration allows slight changes in resistance to be determined, allowing the load cell to make precise and accurate measurements.
Compression load cells tend to be produced using robust materials, which do not rust or scratch easily, this is because the base plate must be totally uniform to ensure accurate readings. Often a hardened cover may be placed on the base plate for enhanced protection.
Compression cells are designed to be extremely compact for space-sensitive applications. They can also be used for applications with extreme loads – HBM can provide compression load cells that can handle up to 50 T.
The high accuracy of compression load cells, and their ability to measure off-center loads, means they find application in industries where products are sold by weight. The measurements taken by compression load cells remain accurate over a long time period, which can be further enhanced with HBM’s calibration services.
The simplicity of measurement provided by load cells facilitates the taking of rapid measurements – increasing the measurement throughput and lowering operational costs.
Compression Load Cells from HBM
HBM can provide a variety of compression load cells, which are specialized for plant engineering, processing weighing and tank weighing applications. These load cells have accuracies of up to 0.1% and can measure between 50 kg and 5 T.
HBM has approvals for the installation of load cells in measurement systems that must adhere to weights and measurements standards or for use in environments with explosion risks. If required, international certificates can be provided.
This information has been sourced, reviewed and adapted from materials provided by Hottinger Baldwin Messtechnik GmbH (HBM).
For more information on this source, please visit Hottinger Baldwin Messtechnik GmbH (HBM).