The Industries That Use Scales & How Scales Measure Weight


How Do Scales Work

Scales are such a common object in households that is easy to forget how important they are. They aren’t just used to see how the new diet is working but also for a wide range of processes in manufacturing processes. Scales are used to convert and applied force into a digital reading through the use of electrical circuits. There are different weights that scales can convert the applied force ranging from air pressure to changes in electrical resistance of a squashing substance. It is easy to use a scale but how easy is it to understand how it works?

How Scales Measure Weight

Digital scales are used in manufacturing, laboratories, and households. They use both mechanical and physical properties to measure forces such as weight which is the force an object experiences due to gravity. Mechanical and digital scales are very similar in how they work but differ in how they display the value of the weight. Both scales use mechanical components to measure the degree of weight.  Scales measure weight using a load cell. A load cell is a transducer which is a device that is able to convert energy from one form into another. Load cells change mechanical energy that is caused by the object pushing down onto the scale into an electrical signal. A strain gauge is used to read the compression or tension caused by the object and then notes the electrical resistance. The material that is squashed by the object on the scale is electrically conductive. The squashing causes a change in the electrical resistance of the squashing substance which varies due to the gauge factor. The gauge factor is the degree of resistance that the specific squashing substance undertakes. The area in which the squashing substance is placed is called a Wheatstone bridge. This is used as an electrical circuit that can detect the changes in the electrical resistance by comparing it against other known electrical resistance that are within the circuit. A Wheatstone bridge can consist of one to four strain gauged. Multiple gauges can be used to increase the sensitivity and precision of the scale. Temperature can affect the electrical resistance so using multiple strain gauges can prevent against any discrepancies that temperature fluctuation could cause. The load cell that measures the quantity of the resistance change sends a signal to the central computer that displays the degree of compression as a value of weight.

The Science Behind Strain Gauges in Scales

There are different types of scales that are used throughout the varying industries. Some require precise and accurate readings so they often use pneumatic load cells. Pneumatic load cells use air pressure to calculate the weight of an object. They measure the air pressure required to balance the force that the object on the scale imposes. Pneumatic Scales are often used in the food industry or at sites that contain hazardous materials  where precision is key. They can weigh a huge variety of weights with significantly high accuracy. However they have the disadvantage of taking an inconvenient amount of time in producing the display of the weight because the process is so precise.

Industries that use weighing tanks or hoppers often use Hydraulic load cells. Hydraulic load cells don’t use electricity. This is important in industries were water is present. They are expensive and complicated to use but they can be used for multi million pound objects. Each weighing technique is advantageous for differing industries however the principle of how the scales work is the same.