Load cells are pretty robust pieces of kit, designed to withstand continual use in a variety of conditions, from underwater to freezing temperatures. However, their accuracy diminishes over time, and they do not last indefinitely. So, if your load cells are not performing as well as they did, what should you do?
Accuracy is key
Inaccurate load cells are more than just a pain, they can also be a danger. If used to track force, weight or torque, inaccurate data from your load cells will affect your ability to judge what is actually happening in real time. At the very least, inaccuracy will skew maintenance schedules and corrupt datasets.
There are five main factors that affect the accuracy of load cells in the working environment:
Creep is the change in accuracy that occurs when load cells are under constant pressure in otherwise constant conditions.The load cell gradually deforms over time, resulting in data that ‘creeps’ beyond the maximum deviation required.
The ambient temperature will affect how well a load cell performs. All our load cells have a wide temperature range in which they can operate with minimal impact on accuracy. This is the specification for our 340 High Capacity Series, for example:
Load cells are affected by high humidity levels, and should be chosen with care. This also applies to load cells in environments where they need to be cleaned or sprayed down and can be exposed to misted water. If you’re in any doubt as to whether your project requires a standard load cell or a waterproof one, fro example, just contact us. We’re happy to help with advice on all things load cell.
If one side of a load cell is loaded more than the other, the load cell will provide inaccurate readings and may distort over time. The same applies to any load cell mounting that is not correctly centred, resulting in inaccurate data again.
If you swap out load cells from one job to another, they may not be suitable for the new task or location, and give inaccurate readings.
As one US company says:
“The calibration of instruments is all about confidence in the measurement results you’re getting. Calibrating your instrument assures you that your measurements are accurate within the specification limits that led you to select the instrument in the first place.”
The benefits of recalibration include:
- Elimination of false passes or false failures, affecting the end result
- No distortion of data-based findings that lead to inaccurate assumptions
- Conformation to global weights and measures and other standards
- Regulatory or contractual requirements
- Spotting patterns or problems before they happen
- Accurate data over a sustained period of time
Recalibrate or replace?
As we said at the start, most load cells are robust. They won’t usually wear out or completely fail under normal usage, but their accuracy will diminish. Most load cell manufacturers, including ourselves, recommend you recalibrate your load cells annually, more often if they are under constant load, are vital for safety, or are located in hostile environments.
Recalibration will require you to effectively ‘disengage’ the load cell from whatever force it is measuring. You can then either recalibrate it on site, or send to us for recalibration at our manufacturing base in Reading. If you require a Certified Calibration Certificate, we can have your load cells calibrated by a UKAS accredited lab.
Given that accessing load cells can be very time-consuming, and especially if you want them professionally re-calibrated, you may prefer to replace them with new load cells which are pre-calibrated by us. That way, you only have to remove the old load cells and slot in the new ones, saving time and hassle.
Also, if you have to replace one or two cells in a series of four, for example, it would be better to replace all to avoid differences in accuracy between old and new.
On the other hand, there may be nothing intrinsically wrong with your load cells, in which case recalibration is a eco-friendly, ‘green’ solution that minimises waste and maximises the lifespan of your load cells.
Call us about calibration
We’re happy to help with advice on recalibrating any type and any size of load cell, to keep it operating at prescribed levels of accuracy.