Why a scale needs calibration?
The preventive maintenance requires scales calibrated every 3 months to ensure accuracy and linearity. If you don’t use your scale a lot, we’d recommend that you check the scale accuracy every 3 months and do the calibration if the scale is off tolerance.
All the scales need such preventive calibration maintenance. Why a scale will be off after certain usage? Let’s take a look at how the scale works:
Most of industrial scales are using load cells to convert analog forces to digital readouts. Load cells measure force by its sensor called “strain gauge”. A strain gauge is a long length of conductor arranged in a zigzag pattern on a membrane. When it is stretched, its resistance increases:
Strain gauges are mounted in the same direction as the strain and often in fours to form a full ‘Wheatstone Bridge’.
A downward bend stretches the gauges on the top and compresses those on the bottom. A load cell may contain several similar strain gauges elements.
Here is one kind of the load cell:
The strain gauges are mounted on the side of the alloy base. When one end of the base gets force (load), the whole base will be de-shaped thus the strain gauges are stretched. The more force the base gets, the more the strain gauges are stretched. Then the resistance change will be sent to the indicator and the indicator will convert such resistance change into digital readouts. When the force is out (unload), the alloy base returns to its original shape. However, after certain usage, the base may be out of shape permanently, which affects the discrepancy of accuracy and linearity. So we need to recalibrate the scale to reset the zero and full capacity resistance on the indicator.
You can calibrate the scales if you have possession of calibration weights. But if this is not the case we’d recommend you let professionals to do the calibration for you.
We have more than 250 technicians nationwide to serve your technical needs – including regular accuracy check and calibration.
