Friction Welding is a welding process used to join two metal parts together by way of rubbing. The process is relatively simple and produces a strong bond between the materials. It is a reliable and cost-effective process and is used in a variety of industries. It can also be used for joining plastic and ceramic components. In this article, read various aspects of friction welding, and helpful tips to get started.
Post Highlights:
- What is Friction Welding?
- Friction Welding Principle
- Friction Welding Diagram
- Friction Welding Equipment
- Friction Welding Types
- Friction Welding Applications
- Friction Welding Advantages
- Friction Welding Disadvantages
- Friction Welding Employment Areas
- Friction Welding Job Types
- Friction Welding Salary Trends
What is Friction Welding?
This is a solid-state welding process where two pieces of metal are joined together by rubbing them together at high speed and pressure. It causes the materials to soften and bond. The welding technique is relatively new and developed in the 1940s.
The variations include linear friction welding, rotary friction welding, friction stir welding, and friction taper welding. Each variation uses slightly different equipment and technique to achieve the desired results.
Friction Welding Principle
The principle is based on the generation of heat due to the frictional forces between two materials that are in contact and under pressure. Further, this heat softens the materials at the interface and allows them to fuse together.
The process typically consists of two parts, one of which is rotated at high speed while the other is held stationary. The two parts are pressed together under pressure, and the frictional heat generated between them causes the materials to soften and bond together.
The amount of heat generated depends on the rotational speed of the rotating part, the pressure applied, and the materials being welded. The temperature at the interface must be high enough to cause the materials to soften and bond. But not so high as to cause melting or distortion.
The strength of the weld depends on several factors such as the surface finish of the materials, pressure applied, and time/temperature of the welding process. As a result, this makes a strong, and high-quality weld joint.
Friction Welding Diagram
The diagram below demonstrates the welding process.
Initially, the process involves clamping the two pieces of metal. After that, an axial force is generated i.e., a rotational force applied to the joint. This force causes the surfaces to slide against each other in a specific way. As a result, this sliding generates friction and creates heat between two metal pieces.
Further, the friction-created heat melts the metal surfaces at the interface and forms a small pool of molten metal. As the metal cools and solidifies, it forms a strong bond between the two pieces of metal. Then, an operator inspects the welded joint for quality after cooling.
Friction Welding Equipment
The equipment is designed to generate heat and pressure. The equipment consists of components like a drive motor, tooling assembly, power supply, and welding controller.
1. Motor – It is used to generate the necessary force and speed to complete the welding process.
2. Tooling Assembly – This holds the two pieces of metal in place during the welding process.
3. Power Supply – It provides the necessary electricity for the welding machine.
4. Welding Controller – This ensures that the process is properly completed.
5. Additional Equipment – They include jigs and fixtures for holding the parts in place during welding. For producing good quality welds, proper alignment, and clamping of the parts are essential.
The application of welding decides the type of equipment used. Generally, a large-scale industrial application may require more specialized machinery. This consists of automated feed systems, high-power hydraulic systems, and various tools and fixtures. And, manual machines are typically used for smaller-scale applications.
Types of Friction Welding
The various welding types are as follows-
1. Rotary Friction Welding – This is the most common type of welding type and is employed when two parts must be joined together with high rotational speeds. The process involves two pieces of material being pressed together while being simultaneously rotated at high speeds. This imparts typically very strong and durable welds and is used for joining metal components, such as pipes and rods.
2. Linear Friction Welding – It is similar to the rotary welding method. During the process, two pieces of material are moved linearly while being pressed together, instead of rotating them. The process is used when two parts do not require much rotation. The automotive industry used this process for joining plastics and metals.
3. Friction Stir Welding – This is relatively a new form of welding. The process starts with the use of a cylindrical tool that is heated and inserted into the joint between the two pieces of material. As the tool moves through the joint, it generates friction. As a result, it causes the materials to melt and join together. The process is used for joining aluminum alloys and other non-ferrous materials.
4. Ultrasonic Welding – The process involves the use of high-frequency sound waves to weld two pieces of material together. These sound waves generate enough heat and melt the two pieces of material and join them together. The process can create very small welds and is used often in medical device manufacturing.
5. Explosion Welding – This is an advanced welding form. The process involves the application of high-pressure shock waves. They cause the two materials to bond together at a molecular level. This process type can weld that materials which are impossible to weld such as ceramics, metals, and other materials.
6. Thermoplastic Welding – The process involves a heated tool used to melt the surfaces of the materials. Then they are pressed together to form a bond. The process can join thermoplastic materials, such as polypropylene, polyethylene, and PVC.
Applications of Friction Welding
The process is used in many different industries, they include-
1. Automotive Industry – The industry uses this for making car body components such as axle assemblies, exhaust systems, and wheel rims.
2. Aircraft/Aerospace Industry – Here the industry manufactures parts such as engine mounts, landing gear components, turbine blades, and fuselage sections.
3. Medical Device Industry – The industry manufactures parts such as implantable devices, surgical instruments, and diagnostic equipment. It is particularly useful for welding biocompatible materials such as stainless steel, titanium, and cobalt-chromium alloys.
4. Electrical/Electronic Industry – The process manufactures here parts such as terminals, connectors, and switch components. It produces reliable, high-strength welds that can withstand high currents and voltages.
5. Oil/Gas Industry – The industry used it for manufacturing parts such as casing, drill pipe, and production tubing.
6. Military Applications – The process used for producing missiles, ammunition, and military vehicles due to ensure the safety of troops in combat situations.
Advantages of Friction Welding
The following are some of the advantages-
1. Fast/Efficient Process – It can produce welds in seconds, which makes it an ideal choice for mass production in both large-scale and small-scale industries.
2. Environmentally Friendly – The process is environmentally friendly. It does not produce any harmful emissions or waste.
3. Low Maintenance – The process is cost-effective. The machines used require low maintenance and minimal operator intervention.
4. Minimal Distortion – It produces minimal distortion in the materials being joined because the process does not involve melting. So, there is no shrinkage or warping.
5. No Filler Material – It does not require any filler material as the joint is made solely from the two materials being welded together.
6. Strong Welds – The process produces very strong welds that can withstand high stress and strain.
7. Automation – This is possible and results in improved productivity and repeatability.
8. Versatile Process – This can be used to join a wide range of materials, including dissimilar materials. Particularly, the process is useful for joining metals that are difficult to weld using other methods.
Disadvantages of Friction Welding
Some of the drawbacks are as follows-
1. No Identical Results – The process nature makes it difficult to achieve repeatable results even under the same conditions.
2. Weld Quality Check Difficulty– The operator cannot check weld quality easily due to the high temperatures and pressures involved in the process.
3. Can Be Time-Consuming – The process can be time-consuming as it requires expensive tooling (including custom-made tooling)
4. Vibration – It is typically limited to small and medium-sized parts due to the vibration associated with the process.
5. Limited Usage – It cannot weld certain materials such as aluminum and plastic. They may require other welding methods.
Friction Welding Employment Areas
The following industries employ this process and create opportunities.
- Aerospace Industry
- Automotive Industry
- Marine Industry
- Oil and Gas Industry
- Electronic Industry
- Electric Industry
- Medical Device Industry
Friction Welding Job Types
Some of the job titles are as follows-
- Machine Operator
- CNC Machinist
- Friction Stir Welding Tech
- Welding Engineer
- Manufacturing Engineer
Friction Welding Salary Trends
The salary trends in friction welding vary from designation to designation. The average salary of a Machine Operator is $17.47 (hourly), $4,488 (monthly), and $63,384 (yearly) in the United States. The highest hourly paying cities for Machine operators are Indianapolis ($18.75), Phoenix ($18.57), Louisville ($18.16), and Cincinnati ($18.03). In some places, Machine Operators also fetch $23.25 per hour along with various other job benefits and perks. Normally, the salary depends on factors like education, work experience, certification, demands, responsibilities, and rampant market trends. The higher qualifications impart a good salary.
Summary
Friction welding is a process that generates heat by rubbing the surfaces of two materials together at high speed. It has many types. Despite having some usage limitations, it is used in various industries such as automotive, aerospace, medical devices, electrical and electronic components, and oil and gas. The above-mentioned information on friction welding is useful for various personnel working in the welding industry in their respective areas.
