A Deep Dive into Resistance Spot Welding
Resistance welding Yolo Materials Industry 13th, Sep 2023 15:00pm
Resistance welding, also known as resistance welding, is a method used to join materials together. It works by clamping the materials between two electrodes and passing an electric current through them. This current generates heat due to the resistance of the materials, causing them to melt and form a strong joint when cooled.
Principle of The Resistance Welding
Here’s how resistance welding works in simple terms:
- Clamping: The materials to be joined are held firmly between two electrodes.
- Applying Pressure: A certain amount of pressure is applied to hold the materials together securely.
- Passing Current: An electrical transformer in the welding machine sends a high current through the area where the materials are in contact.
- Heating: This current generates heat due to the resistance of the materials. This heat melts the materials, allowing them to fuse together.
- Growing the Weld: The current is maintained for a specific duration, allowing the contact point to grow and ensure a strong bond.
- Activation of Atoms: During this process, the atoms at the contact point become highly active, contributing to the formation of a solid joint.
- Cooling: Once the desired joint is achieved, the welding transformer stops the current. The melted materials cool down and solidify, forming a strong bond.
Resistance welding relies on the heat generated by the electric current passing through the materials’ resistance. This heat causes the materials to reach a melting or plastic state, leading to a metal bonding process. There are four primary types of resistance welding methods: spot welding, seam welding, projection welding, and flash welding.
In summary, resistance welding is a technique that uses electrical current to create heat, which melts materials and forms a durable joint. It’s widely used in various industries for its efficiency and strength in joining materials.
The heat source for resistance spot welding is the resistive heat generated by the passage of current through the weld area. The amount of heat generated by the passage of current through the weldment during resistance spot welding can be determined by the following equation:
Q=I^2Rt
Q – heat generated (J);
I – the connected current (A);
R – resistance between the two electrodes (Ω);
T – energizing time (s)
Certainly, let’s make the explanation more straightforward:
The formula mentioned earlier tells us that the heat in resistance welding depends on three main factors: the welding current, the resistance between the two electrodes, and the time the current flows. Most of this heat is used to create the actual weld point, while a smaller portion dissipates into the surrounding metal.
The amount of current needed to form a specific weld point is influenced by the time the current flows. If the flow time is short, the required current for resistance spot welding will increase.
The resistance (R) between the two electrodes varies depending on the type of resistance welding method being used. In resistance spot welding, this resistance (R) is made up of the internal resistance of the two pieces being welded (Rw), the contact resistance between the two pieces (Rc), and the contact resistance between the electrodes and the pieces (Rcw).
Resistance welding basic types
Spot Welding
This method involves using cylindrical electrodes to apply pressure and electric current, creating a single point of contact between two overlapping workpieces. Details will follow later.
Flash Welding
Flash welding involves welding workpieces along their entire contact surface using resistance welding. It includes flash and upset welding methods.
Projection Welding
In projection welding, workpieces have pre-made projections. When projection welding is applied, one or more fusion cores are formed at the joints. It's a variation of spot welding.
Butt Welding
Butt welding, a method of resistance welding in which the weldments are welded together along the entire contact surface. In addition to resistance butt welding, flash butt welding is also relevant.
Resistance Butt Welding: This is a way to join metal pieces end-to-end. Imagine putting the ends of two metal parts together, heating them up with electrical resistance until they become soft, and then pressing them together firmly. It’s like pressing Play-Doh together, but with heated metal. It’s good for simple shapes and when the weld doesn’t need to be super strong.
Flash Butt Welding: Similar to resistance butt welding, this method also joins metal ends. However, here, when the ends touch, we send a strong electric current through them. This makes a spark or flash, and the metal gets really hot at the ends. The hot metal melts a bit, and then we press the ends together. It’s like creating a hot spot, then squishing the metal ends together to make them stick. It’s useful for specific kinds of welding where precision is important.
Seam Welding
In seam welding, workpieces are assembled, placed between two roller electrodes, compressed, and rotated. This continuous or intermittent application of electric current forms a continuous welded seam. Seam welding is primarily used for joining regular and seal-tight structures.
1-upper weldment; 2-lower weldment; 3-upper electrode; 4-lower electrode; 5-welder power supply
These methods are used for various applications, with resistance spot welding being the most widely used. We’ll provide more details on resistance spot welding with next articles. Please find the link in bottom of this post.
NDB technology
NDB (non-defective bonding) does not require any solder due to. The integration of copper, tungsten, and molybdenum ensures a strong connection with a strength exceeding 130Mpa, without any internal holes.
oxidation resistance
(2) The welding electrode materials is better to have higher oxidation resistance, less tendency to form alloys with weldment materials
Yolo's Resistance Weld Rod
Yolo manufacturer and supply customized resistance spot welding electrode rod for sale. With factory direct price and our advanced NDB(Non-defective bonding) back cast technology, the tip heat conduction ability increase and the work life is longer 2-10 times.
conductivity
Our electrodes have excellent electrical and thermal conductivity, for continuous cooling of the electrode tip. This significantly increases the service life and reduces consumption. Additionally, the tip has been densified, resulting in a high-density and uniform internal structure.
Customized Mahining
With our extensive experience in the production and processing of resistance welding electrodes, we can also provide improved design solutions tailored to your specific needs.
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