Ten major achievements in the history of tribology and lubrication technology(1)
author: Leila
2024-10-21
"In ancient times, around 500,000 BC, humans discovered that rubbing a stick together could produce fire, which is called drilling wood to make fire. Around 3500 BC, humans realized that rolling was less labor-intensive than sliding, so they invented the wheel. Later, humans also discovered that applying certain substances, such as animal fats, on the axles of horse-drawn chariots could make the wheels rotate more freely. Moreover, after refueling, the wheels are not easy to heat up, burn, and wear out so quickly. However, we essentially lack understanding of the specific development process of human understanding of these laws, relying purely on anecdotes."
Overcoming the adverse consequences of friction while retaining the useful properties of friction for us - this is the challenge faced by tribologists, whose scope involves many industries: chemists, materials engineers, aviation engineers, equipment maintenance managers, etc., all involve the study of tribology. How to overcome the adverse consequences of friction while retaining the useful properties of friction is a very complex task. In the history of studying tribology, humans have also undergone a long process of development.
In order to explain the process of human understanding of friction and lubrication principles, Mr. Bob Gresham of STLE wrote this article - "Ten Major Achievements in the History of Tribology and Lubrication
Technology". After many professionals participated in the selection and commentary, Dr. Gresham listed the ten major events, inventions, academic and technological achievements in the history of tribology and lubrication technology.
In the following, we will list the ten major events in the history of tribology development in chronological order.
1. Prehistoric period: use of natural lubricants
According to some historical materials, the earliest record of human use of lubricants was around the 15th century BC. In the tomb of the Egyptian Pharaoh Tehut-Hetep (around 1650 BC), evidence of human use of lubricants was found: people applied olive oil on wooden boards to help carry huge stones.
In addition to this archaeological discovery, earlier evidence has been reported: an artifact unearthed in the tomb of Djehutihotip (around 1800 BC, 800 years after the construction of the Pyramid of Khufu) depicts 172 craftsmen dragging a double-track flat-bottomed sled-like wooden trailer on flat ground to move a huge statue. In front of the wooden board, people are pouring some liquid, which is probably lubricating oil. Another archaeological discovery is the artifact unearthed from Tura Stele, which depicts a similar scene, except that three bulls are dragging a similar wooden trailer on flat ground to move a large stone.
The historical period corresponding to this discovery is about 1580 BC to 1588 BC, 1,000 years later than the Pyramid of Khufu.
In the first century AD, Pliny the Elder compiled the Encyclopedia of Nature, which listed the animal and plant fats used at the time - people continued to use these fats for thousands of years, without much change.
In the process of human use of animal oil as fuel and lubricant, tragedies sometimes occurred. In the last century, sperm whales were almost hunted to extinction because humans needed whale oil, which can be made into high-quality lamp oil. Later, as natural oils became increasingly scarce, humans began to look for other sources of oil, especially petroleum.
In the early history of human use of natural lubricants, greases also deserve our special attention. Since ancient times, animal fats have been one of the most commonly used lubricants because they are easy to obtain. In addition, animal fats have the advantage of good adhesion and work better on wheels. In fact, the earliest lubricant specially formulated by humans was probably grease.
In addition to this archaeological discovery, earlier evidence has been reported: an artifact unearthed in the tomb of Djehutihotip (around 1800 BC, 800 years after the construction of the Pyramid of Khufu) depicts 172 craftsmen dragging a double-track flat-bottomed sled-like wooden trailer on flat ground to move a huge statue. In front of the wooden board, people are pouring some liquid, which is probably lubricating oil. Another archaeological discovery is the artifact unearthed from Tura Stele, which depicts a similar scene, except that three bulls are dragging a similar wooden trailer on flat ground to move a large stone.
The historical period corresponding to this discovery is about 1580 BC to 1588 BC, 1,000 years later than the Pyramid of Khufu.
In the first century AD, Pliny the Elder compiled the Encyclopedia of Nature, which listed the animal and plant fats used at the time - people continued to use these fats for thousands of years, without much change.
In the process of human use of animal oil as fuel and lubricant, tragedies sometimes occurred. In the last century, sperm whales were almost hunted to extinction because humans needed whale oil, which can be made into high-quality lamp oil. Later, as natural oils became increasingly scarce, humans began to look for other sources of oil, especially petroleum.
In the early history of human use of natural lubricants, greases also deserve our special attention. Since ancient times, animal fats have been one of the most commonly used lubricants because they are easy to obtain. In addition, animal fats have the advantage of good adhesion and work better on wheels. In fact, the earliest lubricant specially formulated by humans was probably grease.
2. The ancients discovered that rolling can reduce friction
When selecting the top ten events in the history of tribology, many readers recommended the invention of the wheel - reducing friction by rolling. Some people suggested that it should be the axle, because the axle is older, and it is precisely because of the axle that the purpose of the wheel has been changed, turning it into a useful tool.
However, many people who participated in the selection are more inclined to this view: wheels are indeed important, but it is the bearings, not the wheels, that really make objects roll.
In the archaeological discoveries of ancient Egypt, it was found that people used rolling logs as auxiliary tools to carry heavy objects. Some records showed that pebbles or round stones were used. In the Roman era, some anti-friction tools had already appeared, including the initial anti-friction beads, cylindrical rollers or rollers with spindles at the tail end.
Leonardo da Vinci was a versatile figure in the Renaissance. Not only literary works but also some scientific manuscripts were handed down, including some of the earliest basic principles of tribology. Some of his surviving manuscripts were obviously bearing diagrams for anti-friction.
Between Leonardo da Vinci and us, there was an era of rapid scientific development - the Industrial Revolution. "As far as we know, the real anti-friction bearings began in the early 1880s, when German Friedrich Fischer invented a process that could mass-produce high-precision spherical rollers."
However, many people who participated in the selection are more inclined to this view: wheels are indeed important, but it is the bearings, not the wheels, that really make objects roll.
In the archaeological discoveries of ancient Egypt, it was found that people used rolling logs as auxiliary tools to carry heavy objects. Some records showed that pebbles or round stones were used. In the Roman era, some anti-friction tools had already appeared, including the initial anti-friction beads, cylindrical rollers or rollers with spindles at the tail end.
Leonardo da Vinci was a versatile figure in the Renaissance. Not only literary works but also some scientific manuscripts were handed down, including some of the earliest basic principles of tribology. Some of his surviving manuscripts were obviously bearing diagrams for anti-friction.
Between Leonardo da Vinci and us, there was an era of rapid scientific development - the Industrial Revolution. "As far as we know, the real anti-friction bearings began in the early 1880s, when German Friedrich Fischer invented a process that could mass-produce high-precision spherical rollers."
3. Discovery of the friction principle from 1495 to 1950
In the Renaissance, thinkers like Leonardo da Vinci began to study the laws of friction. In 1495, Leonardo da Vinci introduced two basic laws of tribology: friction is independent of the size of the contact surface; friction is proportional to pressure. Although Leonardo da Vinci discovered these laws of friction, no one knew about them for many years because he did not formally publish his observations.
More than 200 years later, in 1699, French physicist Guillaume Amontons (1663-1705) also discovered these two basic laws of tribology. Through reasoning, he found that the main cause of friction is that when an object moves on the surface of another object, work needs to be done, causing deformation and wear between the contact surfaces.
However, it was not until 1785 that Charles August Coulomb further developed Amontons' friction theory and determined the second law of tribology - what we now know as Coulomb's friction law, which is basically the same as the friction law we know today. Coulomb's law is stated as follows: friction is proportional to the normal pressure between the contact surfaces. Although this friction law applies to the friction between many contact surfaces, it is not a basic law that applies to all situations and does not apply to large objects.
The great physicist Newton discovered many basic laws of mechanics and motion, including further discoveries in tribology. Newton discovered that dynamic friction has nothing to do with speed and velocity, which is the third law of tribology.
In 1950, British scientists Phillip Bowden and David Tabor explained the law of friction. They believed that when objects come into contact, the actual contact area is very small, and not the entire surface is in contact. On the surface of an object, even if it looks very smooth, it is actually some uneven peaks when magnified. It is actually these undulating peaks that are in contact, not the entire surface. When objects come into contact, the greater the positive pressure, the more the two contact surfaces are squeezed, the more peaks are in contact, and the greater the friction. Bowden and Tabor further determined that friction depends on the adhesion between the peaks that come into contact with each other.
However, as we analyze the friction between contact surfaces at the level of individual molecules, we understand that these macro friction laws also have limitations, and that the interaction between contact surfaces is very complex at the microscopic level.
More than 200 years later, in 1699, French physicist Guillaume Amontons (1663-1705) also discovered these two basic laws of tribology. Through reasoning, he found that the main cause of friction is that when an object moves on the surface of another object, work needs to be done, causing deformation and wear between the contact surfaces.
However, it was not until 1785 that Charles August Coulomb further developed Amontons' friction theory and determined the second law of tribology - what we now know as Coulomb's friction law, which is basically the same as the friction law we know today. Coulomb's law is stated as follows: friction is proportional to the normal pressure between the contact surfaces. Although this friction law applies to the friction between many contact surfaces, it is not a basic law that applies to all situations and does not apply to large objects.
The great physicist Newton discovered many basic laws of mechanics and motion, including further discoveries in tribology. Newton discovered that dynamic friction has nothing to do with speed and velocity, which is the third law of tribology.
In 1950, British scientists Phillip Bowden and David Tabor explained the law of friction. They believed that when objects come into contact, the actual contact area is very small, and not the entire surface is in contact. On the surface of an object, even if it looks very smooth, it is actually some uneven peaks when magnified. It is actually these undulating peaks that are in contact, not the entire surface. When objects come into contact, the greater the positive pressure, the more the two contact surfaces are squeezed, the more peaks are in contact, and the greater the friction. Bowden and Tabor further determined that friction depends on the adhesion between the peaks that come into contact with each other.
However, as we analyze the friction between contact surfaces at the level of individual molecules, we understand that these macro friction laws also have limitations, and that the interaction between contact surfaces is very complex at the microscopic level.
4. Drake's oil well and the advent of the world's lubricant industry in 1859
On August 27, 1859, Drake drilled the first oil well in Titusville, Pennsylvania, USA, located 69.5 feet underground. The United States and the world regard this time as the beginning of the world's oil industry. In the following years, due to the huge demand for energy in the Industrial Revolution, oil wells emerged like mushrooms after rain, and the oil industry also led to the prosperity and development of cities. Lubricants made from petroleum are also promoted in various industries: manufacturing, transportation, power generation, communications and other industries all use petroleum-based lubricants.
5. 1883-1905: Principle of fluid dynamic lubrication
Before the Industrial Revolution, lubrication had not yet risen to the scientific and theoretical level, but only relied on experience or word of mouth. In 1883, the British began to explain the rules of fluid dynamic lubrication, among which Beauchamp Tower did actual tests. He used a special test bench to simulate the lubrication state of the sliding bearing of the truck axle. After experiments, Tower found that the friction coefficient was closely related to the load and bearing speed, and discovered the phenomenon of fluid dynamic pressure.
In the final stage of the experiment, Tower drilled a refueling hole in the sliding bearing and found that the oil would flow from the refueling hole to the bearing cover. He installed a pressure gauge in the refueling hole and found that the pressure was very high. Even the pressure gauge could not measure such high pressure. Tower realized that there was an oil film layer inside the bearing that could carry a large load. Later scientists also confirmed this discovery through research.
In 1886, Osborne Reynolds proposed the differential equation of lubrication theory, successfully revealed the mechanism of dynamic pressure generated by fluid film, and laid the foundation for modern fluid lubrication theory. The Reynolds equation is a second-order partial differential equation, a form of the Navier-Stokes equation.
In 1905, Arnold Sommerfeld further developed the theories of Tower and Reynolds and formally formed the theory of fluid dynamic lubrication.
After laying the foundation for the theory of lubrication, human understanding of fluid dynamic lubrication continued to develop. Fluid dynamic lubrication is named after the mechanism of lubricating film generation: relative motion occurs between solid contact surfaces, which generates liquid dynamic pressure, forms a lubricating film, separates the two friction surfaces and bears the load.
We all know that the surface of an object is uneven and has many raised peaks. When two surfaces come into contact, the peaks will come into contact. If one of the planes slides on the other, the friction will increase. The peaks that come into contact with each other will break under force, and the surface of the object will also be worn. In fluid dynamic lubrication, the lubricant forms a lubricating film to separate the contact surfaces and prevent them from direct contact, so as to achieve the purpose of reducing friction and avoiding wear. To achieve fluid dynamic lubrication, the following conditions need to be met: the geometric structure and size of the equipment, the movement speed of the object, and the viscosity of the liquid lubricant can form sufficient liquid dynamic pressure, and rely on liquid dynamic pressure to carry the load. The dynamic pressure of the liquid forces the contact surfaces to separate, generating an upward support force to prevent them from directly contacting.
Fluid dynamic bearings rely on the support force generated by the dynamic pressure of the fluid to carry the load. The most typical example is the sliding bearing, which is widely used in machines and vehicles.
In the final stage of the experiment, Tower drilled a refueling hole in the sliding bearing and found that the oil would flow from the refueling hole to the bearing cover. He installed a pressure gauge in the refueling hole and found that the pressure was very high. Even the pressure gauge could not measure such high pressure. Tower realized that there was an oil film layer inside the bearing that could carry a large load. Later scientists also confirmed this discovery through research.
In 1886, Osborne Reynolds proposed the differential equation of lubrication theory, successfully revealed the mechanism of dynamic pressure generated by fluid film, and laid the foundation for modern fluid lubrication theory. The Reynolds equation is a second-order partial differential equation, a form of the Navier-Stokes equation.
In 1905, Arnold Sommerfeld further developed the theories of Tower and Reynolds and formally formed the theory of fluid dynamic lubrication.
After laying the foundation for the theory of lubrication, human understanding of fluid dynamic lubrication continued to develop. Fluid dynamic lubrication is named after the mechanism of lubricating film generation: relative motion occurs between solid contact surfaces, which generates liquid dynamic pressure, forms a lubricating film, separates the two friction surfaces and bears the load.
We all know that the surface of an object is uneven and has many raised peaks. When two surfaces come into contact, the peaks will come into contact. If one of the planes slides on the other, the friction will increase. The peaks that come into contact with each other will break under force, and the surface of the object will also be worn. In fluid dynamic lubrication, the lubricant forms a lubricating film to separate the contact surfaces and prevent them from direct contact, so as to achieve the purpose of reducing friction and avoiding wear. To achieve fluid dynamic lubrication, the following conditions need to be met: the geometric structure and size of the equipment, the movement speed of the object, and the viscosity of the liquid lubricant can form sufficient liquid dynamic pressure, and rely on liquid dynamic pressure to carry the load. The dynamic pressure of the liquid forces the contact surfaces to separate, generating an upward support force to prevent them from directly contacting.
Fluid dynamic bearings rely on the support force generated by the dynamic pressure of the fluid to carry the load. The most typical example is the sliding bearing, which is widely used in machines and vehicles.
The Replacement Time of Grease
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