Inertia friction welding, or spin welding, is an eco-friendly, metal joining process used to bond similar or dissimilar metals together. This process is accomplished without the use of filler metals, fluxes, or shielding gases like conventional welding. It also minimizes energy consumption, produces no fumes, gases, smoke, or waste. Initially, friction welded components were, as a rule, circular. With today’s technologies, the applications, components, material types, sizes, and shapes that can be joined are endless. Spinweld offers – direct-drive friction welding and inertia friction welding. (See Advantages of Friction Welding)
Friction welding, commonly known as spin welding, is a controlled machining process for joining SIMILAR or DISSIMILAR (Bi-Metal) combinations of materials. The ultimate goal of spin welding is to have a 100% weld throughout the full joint interface. This means, given suitable materials, the weld union or interface strength is equal in strength to that of the parent metals. This process yields a high-strength, low-stress, small heat-affected zone (HAZ) weld with no porosity, and in most cases, eliminates the need for costly pre-machining or costly tooling. You may have heard of this friction welding process or welding interface referred to as spinning, welding, fusing, bonding, marring, or union. Friction welding is a well-established process developed in the 1890s and is widely accepted throughout many different industries and global markets.
A simple explanation defines the friction welding process as rotating one component against a fixed component under pressure. This action efficiently prepares and cleans the weld interface, and generates sufficient low temperature, frictional heat, for at least one of the materials to become plastic at the joint interface. This “Solid State” (non-melting), joining process produces a merging between the materials via the heat developed by the induced rubbing motion and the applied load between the two surfaces.
Both direct drive and inertia friction welding provide a superior union of materials by rotating one component against a fixed component under pressure. The difference is the energy source, RPMs, and timing/distance as pressure is applied.
Energy is provided by an electric motor directly connected to the machine spindle. This energy source is infinite with respect to time and is applied to the interfacing materials until the proper total heat or plastatic state is obtained. Speed is held constant for a selected time and/or distance, as pressure is varied. When the desired plastatic state is achieved, the rotating component is stopped and a forging load is applied to complete the joining process, making the parts as one. Greater total heat is achievable over inertia friction welding which may slow the rate of cooling resulting in slightly longer cycle times.
Energy is provided by the machine’s kinetic energy that is stored in a rotating system or mass. The energy available in a stored energy system is finite. This requires specific parameters of mass/weight, speed, and pressure to meet the requirements of the weld union. When the desired rotational speed is achieved, kinetic energy is transferred into the freely rotating part. Constant forge pressure is applied until a plastic state is reached. Rotation stops due to controlled pressure as the desired total displacement length of material (upset) are met. Rotational speeds are normally higher than direct drive friction welding. The majority of the total displacement comes at the very end of the weld cycle as compared to being spread out over the middle to the end of the cycle.
Step 4 - Products manufactured using Inertia Friction Welding