There are many types of friction welding methods that can optimize your manufacturing process. In this article, we will review several different types. Understanding these different types will help you decide which can increase precision and reduce total cost and cycle time for your application.
What Is Friction Welding?
Before we break down the different types, let’s define the solid state welding process known as friction welding. Solid state welding refers to welding processes that don’t use external heat. Instead, external pressure is applied to a solid state to form the weld. In friction welding, the workpieces to be joined rotate relative to the other. This movement creates friction, which replaces material on the contact surface. A high pressure force is applied until the weld is complete. Friction welding can be used to join a variety of metal (such as steel and aluminum) bars and tubes up to 100 mm in diameter.
How Friction Welding Works
Friction welding works by following the fundamentals of friction. The process uses friction to create a plastic-forming heat at the weld interface. For example, the friction heat used on steel is usually around 900–1300 degree centigrade. After the appropriate temperature is achieved, an external pressure force is increasingly applied until the workpieces form a permanent joint.
While there are several different friction welding types, they all follow a common working principle. First, one workpiece is placed in a rotor-driven chuck, while the other is held stationary. The rotor allows the mounted workpiece to rotate at high speeds. An increasing amount of pressure force is applied to the stationary workpiece, which brings it closer to the rotating workpiece. When the workpieces touch, a high friction force is created and generates heat at the contact surface. The rotor is stopped once the heat reaches a plastic-forming temperature. The pressure force continues to be applied until the weld is complete.
5 Friction Welding Types
1. Inertia Friction Welding
What is inertia friction welding? Inertia welding features an engine flywheel and shaft flywheel. The chuck is connected to the motor by the flywheels. At the start, the flywheels are connected to each other. After the friction speed is at its specified max, the engine and shaft flywheels separate. Separate from the engine flywheel, the shaft flywheel experiences inertia and stops. Then the pressure force continues to be applied until the weld is complete. Learn why you should combine inertia welding with CNC machining.
2. Continuously Induced Friction Welding
In this process, a band brake is connected to the rotor instead of an engine flywheel and shaft flywheel. Once the friction heat reaches the plastic-forming temperature, the band brake stops the rotor. But the pressure force continues to be applied until the weld is complete.
3. Linear Friction Welding
This process is similar to inertia friction welding; however, the moving chuck doesn’t spin. Instead, it oscillates in a lateral motion. Also, it operates at a much lower speed. Therefore, the workpieces are held under pressure throughout the entire process. This process requires the workpieces to feature a high shear strength and more complicated machinery than inertia welding. On a positive note, it offers the capability to join parts of any shape (instead of just circular interfaces).
4. Friction Surfacing
Friction surfacing applies coating material to a substrate. In this process, a coated rod rotates under pressure to create a plasticised layer at the interface with the substrate. The substrate is moved across the face of the rotating rod to deposit a plasticised layer. Depending on the diameter of the rod and coating material, the plasticised layer is between 0.2–2.5 mm thick.
5. Orbital Friction Welding
Orbital friction welding is also similar to inertia welding. However, it uses a more complicated machine to create an orbital motion. This motion allows the moving workpiece to rotate in a small circle. The circle is smaller than the joint size.
Friction welding can be used to build better industrial rollers, tubes, and shafts. The process is often used to manufacture these subassemblies for industrial printers, material handling equipment, as well as automotive, aerospace, marine, and oil applications. Other examples of components include gears, axle tubes, drivelines, valves, hydraulic piston rods, truck roller bushes, pump shafts, drill bits, connection rods, etc.
Friction welding is an eco-friendly process that doesn’t create smoke or release other harmful toxins into the atmosphere. Next, it offers a lot of control over the heat-affected zone, which reduces change to material properties. It also doesn’t require filler metal (which saves cost on raw material). Last, friction welding offers simple automotion, fast speeds, efficient welds, and the ability to combine a variety of metals.
Ready to Start Friction Welding?
If friction welding sounds like it could benefit your application, please contact us. During our conversation we can discuss which type of friction welding might be your best option and if we are the best-fit provider to inertia weld your subassemblies.