Afiq Anwar, Syafiq Sarizan, Zahir Azmi and Ahmad Zul Irfan Faiz
Fakulti Kejuteraan Elektrik dan Elektronik Universiti Malaysia Pahang
Universiti Malaysia Pahang, 26600 Pekan Pahang
018-3899895 * [email protected]
Weighing scale is a measuring instrument to determine the weight or mass of the object. The mechanical scale is used to describe the heavy equipment used to measure the mass, energy, tension and resistance of the object. It is used without the need for power supply. Among the types of mechanical scale include spring scale, hanging scale, triple beam balance and lift gauge. Electronic digital scales often show weight as numbers. Normally, on liquid crystal display (LCD). It is versatile as they can perform calculations on measurements and transmit them to other digital devices. In a digital scale, gravity causes the spring to change, and the amount of deformation is measured by one or more transducers called a strain gauge. The strain gauge is a conductor whose electrical resistance changes as the length changes. The strain gauge has a limited capacity and a larger digital scale may use a hydraulic transducer called a load cell. The voltage is charged on the device, and the weight causes the current through it to change. The current is transformed into digital numbers by analog-to-digital converter, translated by digital logic to the correct unit, and displayed on the display. Usually this device is run by a microprocessor chip.
F = amount of force applied
X = the distance traveled
k = the constant stiffness
Most humans use the scale to replace objects, materials, animals, and people. However, these instruments can work in many ways. In this post, we will provide a basic explanation of the various mechanisms that allow such a scale to function. In fact, it is practicable that all scales use the same mechanism, so we will address the most commonly used problems in this regard. The traditional scale consists of two plates or bowls suspended at equal distance of a fulcrum. One plate holds an object of unknown mass (or weight), while known masses are added to the other plate until static equilibrium is achieved and the plates level off, which happens when the mass on each plates is equal.
A spring scale will make use of a spring of known stiffness to determine mass (or weight). Suspending a certain mass will extend the spring by a certain amount depending on the spring’s stiffness (or spring constant).
As explained in Hooke’s law, the weight of the object, the more the spring stretched. There are several other types of scales that use different physical principles. Some scales can be calibrated to read in units of force (weight) Units of force (weight) units are like newtons rather than mass units
like kilograms. Scales are often used extensively in commerce. Many scales are also sold and wrapped in bulk.
The weight scale is the first mass measurement instrument created once. It is also known as a mechanical weight scale. In the traditional way, it consists of flat lever. This horizontal lever spins with the same long arms, beams, and weighing heavily from each other. Unmeasured mass is placed in one pan. The standard mass will be added to the other pans until the beam is close to the balance. In the balance of precision, a more precise mass determination is given by the sliding mass position moving along the graduated scale. Technically, the balance compares the weight to the mass. However, in certain gravity fields such as gravity of the earth, the weight of an object is proportional to its mass. Then the standard mass used with the tray is usually labeled in mass units such as grams (g) or kilograms (kg).
2. The working principle of mechanical weight scale
2.1 Mechanical scale
The scales use quite different physical principles. Mechanical components at scale are to measure weight and other forces. Bump is just a force on objects caused by gravity. An example of the spring scale, measuring the weight using the law of Hooke, which links the strength of weight to stretching or spring compression made from the given material. Not all scales use springs. But all weight gauge uses mechanical components. Thus, the mechanical scale and the digital scale differ only in the way they display the weight either mechanically or electronically. In other cases, the scale uses an analog-to-digital converter that translates continuous reading data from scale to discrete digital information. Measuring instruments used in mechanical scale is spring balance and hydraulic balance.
2.2 Spring scale
The spring scale is one of the most basic tools used in mechanical scale to measure the weight of the object. It is only one spring attached at one end and one indicator at the scale on the other. There are hooks on the bottom of the scale of the spring to put the object to be weighed.
Fig.1 Spring scale
The theory of Hooke’s Law and its Application will be discussed in this article, in order to understand the theory of Hooke’s Law and its application properly, consider the description below. a. Hooke’s Law Theory According to Robert Hooke objects are divided into two types, namely objects that are plastic and objects that are elastic. Plastic objects are objects that will experience changes when subjected to force and the object cannot return to its original position after the force has been removed. While elastic objects are objects that will experience changes when subjected to force and objects can return to their initial state after the force has been removed. Examples of elastic objects around us are rubber bands, catapults, arrows, peer, spring. Robert Hooke conducted an experiment to investigate the relationship between changes in elastic matter and the force applied to objects. Robert Hooke used springs in his experiments. From his experiments Robert Hooke then put forward a law about the relationship between force and changes in the length of a spring which became known as Hooke’s legal theory. According to Hooke the spring will experience a change in length proportional to the force applied to the spring. The formula for Hooke’s Law is written :
F = – k. ?x
With F = force (N),
k = spring constant (N / m),
?x = Change in spring length (m).
Negative sign indicates spring force opposite to the external force applied to the spring
There are some drawbacks on the spring scale even though the spring scale is a useful tool for gaining weight estimates. It has some drawbacks that need to be calibrated perfectly to accurately measure the power. The spring scale should also be checked regularly for signs of relaxation. Given that the springs will naturally diminish after repeated stretches, the scale needs to be replaced after a while, as the reduced spring will result in the wrong results. As long as the spring is not expanded beyond its elastic boundary, the spring scale is a great way to get an approximate approach.
Spring balancer can be used to measure the weight in different types, depending on the particular stiffness of the spring. Small scale with sensitive eyes can be used to measure differences up to gram or less, although this will break if weight is attached to them. A stronger spring is used on a scale that can measure thousands of pounds.
2.3 Hydraulic Scale
It is common for hydraulic scales in high-capacity applications. For example crane scales to use hydraulic power to detect or measure the mass. Test force applied to piston or diaphragm and transmitted via hydraulic path to dial indicator based on Bourdon tube or electronic sensor The hydraulic scale is intended to help you determine the estimated weight for use in loading the vehicle or trailer. The hydraulic scale also can help in a variety of occupations where putting items on a scale is not practical. It can be hung from a block and lifts a lift, frame, or forklift bar. It can also be used horizontally to test tensile strength. He has found practical uses in agriculture to weigh straw and tobacco.
Fig 2 Hydraulic scale
The hydraulic scale is designed to provide accurate precision at reasonable prices. The gauge used in the standard model is assessed exactly in 2% of the overall overall gauge at mid-range reading. At high or low scale readings, the accuracy is 3%. In most cases it is close enough to make sure you are in a safe loading parameter.If your accuracy is higher, different types of scales are recommended. For that reason, the hydraulic scale can not be used for trading purposes (goods sold by weight). It is difficult to get budget figures to load heavy items, and in that context it is also stated that it is a very good choice for the money.
3. The working principles of electronic scale
Electronic digital scales display weight as a number, usually on a liquid crystal display (LCD). They are versatile because they may perform calculations on the measurement and transmit it to other digital devices. In a digital scale, the force of the weight causes a spring to deform, and the amount of deformation is measured by one or more transducers called strain gauges.
Strain gauges have many types. The ordinary pressure gauges are for the Stack-sensitive grid (3-6?m) made of thin metal foil in a plastic film (15-16?m) so-called base and then covered with thin film to form a lamina.Strain gauge principleThe tensile gauge will be measured through the weight of the object, so that it expands and the contract together with the tension of the object will be measured so that the metal foil is in the stretched or shorter object with tension. Many metals change their durability when mechanical is stretched or shortened. Strain gauge is the application of this principle, measured by measuring the strain resistance of this variable measured. The tensor typically uses the copper-chromium alloy sensitivity, the rate of change resistance is constant, and the tension is proportional to the relationship. thats it:Among them, R: strain measuring the original resistance ? (ohm)?R: elongation or compression resistance ? (ohm) is caused by tension K: Fixed Rate (continuous strain gauge)E: tension. Different metal materials have different proportions of the K-coefficient of K. Copper-chromium K about 2. In this way, the tension measurement is exchanged by the strain gauge to the size of the resistance of the change. However, since tension is a relatively small change, the resulting changes in the match are also very small.To measure any small resistance in change is very difficult, the general resistance meter can not meet that requirement. To measure this small change in the opposition, we use a dedicated tension gauge with the Wheatstone bridge.
On a mechanical scale, people who use the mechanical scale must be close to the scale to read values or gauges and errors in readability that errors can occur easily. The person also must then write a scale reading to take on average and do math to lose weight, calculate the counting part, and possibly convert the weight unit to the volume unit, for example pound for gallons.Another conversion type may be from pound to kilogram and vice versa. The probability of human error is high and easy work will become more difficult and will add problems. Using digital scale greatly reduces or eliminates opportunities for human error. This scale also has high accuracy from the use of electronic load cells, and the scale readings can be displayed on large LCD screens. The processor can perform all the required mathematical functions, and the data from the scale can be put into the computer or to the storage device for further storage and analysis. The digital scale control can be done by way of touch or color touch through the computer connected to the scale. Users do not necessarily need to be close to scale. The digital scale has other important advantages as well and it may change the way you think of scale in the production environment.
We thank Dr, Muhammad Sharfi Najib for assistance with the help of how the weight scale work and Dr. Dwi Prebanti for comments that greatly improved the manuscript. We are so grateful to all of those with whom I have had the pleasure to work during write this article. Each of the members had give a great teamwork , great responsibility towards this assignment and a professional guidance from each of the members and taught a great deal about both scientific research and life in general. I would especially like to thank Prof. Dr. Hamzah, the lecturer of Electric and electronic faculty. As my teacher and mentor, he has taught me more than I could ever give him credit for here. By doing this assignment he had thought me a lot, by his example, what a good engineer and as a researcher should be.
We would also like to show our pleasure to the Ahmad Faiz form Universiti Malaysia Pahang for sharing their knowledge about mechanical and electronic scale with us during the course of this research, and we thank Afiq, Isyraf and Muaz reviewers for their opinion and ideas to realiazed the assignment.
We are also immensely grateful to Dr. Bakri the program leader of Electrical Power course for their comments on an earlier version of the article, although any errors and mistakes are our own and should not blame other person from our own mistakes.
Nobody has been more important to us in the pursuit of this research than the members of my family. I would like to thank my parents, whose love and guidance are with me in whatever I pursue. They are the ultimate role models.
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