What is projection welding process?
Like spot welding, the projection welding process relies on heat generated by an electric current to join metal pieces together. Projection electrodes are capable of carrying more current than spot welding electrodes and can, therefore, weld much thicker materials.
What are weld parameters?
The four important parameters are the welding current, wire electrode extension, welding voltage and arc travel speed. These parameters will affect the weld characteristics to a great extent. Because these factors can be varied over a large range, they are considered the primary adjustments in any welding operation.
Does projection welding use pressure?
Projection welding is a form of resistance welding which uses pressure and electrical current to join two or more metal parts that have been designed to meet at one or more specific points with the maximum amount of contact.
How do you measure projection welding strength?
Strength of a projection weld can be calculated to a simple approximation by area of the dimple and assuming base metal properties for shear/tensile strength, based on type of loading during testing.
Which type of welding is done in spot welding?
Spot welding (also known as resistance spot welding) is a resistance welding process. This welding process is used primarily for welding two or more metal sheets together by applying pressure and heat from an electric current to the weld area.
What electrode is used for projection welding?
Refractory electrode materials, such as tungsten/copper, tungsten, or molybdenum are used for applications such as projection welding inserts, where the electrode contact area is at least three times the weld size.
What are the five parameters of welding?
The 5 Parameters of Welding
- Length of Arc.
What are the characteristics of projection welding?
PROJECTION WELDING is a variation of resistance welding in which current flow is concentrated at the point of contact with a local geometric extension of one (or both) of the parts being welded. These extensions, or projections, are used to concentrate heat generation.
How are spot welding parameters calculated?
Spot welding parameters include:
- Electrode force.
- Diameter of the electrode contact surface.
- Squeeze time.
- Weld time.
- Hold time.
- Weld current.
What are the three principal phases of spot welding?
Spot Welding occurs in three stages: Electrodes seated in a weld head are brought to the surface of the parts to be joined and force (pressure) is applied. Current is applied through the electrodes to the workpiece to melt the material.
What is the total energy of projection welding?
The total energy (Energy = Power x Time) may be the same for a welding process point in quadrant II and IV, but it is the rate of energy delivery that is critical for projection welding. The process window size can be increased by proper selection of materials (electrodes and parts), part design, welding equipment, and process parameters.
How is a projection weld different from a stamped Weld?
A typical resistance weld between two flat sheets (left) is compared to a projection weld (right). The dashed lines show the flow of welding current. Coined or machined projections do not cause the same concerns as a stamped projection, as there is no risk of premature projection collapse during welding.
Are there any major problems with projection welding?
However, one potential difficulty for the success of projection welding is the cleanliness of the parts or presence of surface films that can inhibit bonding. This can manifest itself in the likely presence of an oxide layer on some parts, for example ones subjected to steam treatment, typically on ferrous sintered parts.
What kind of electrodes should be used for projection welding?
The electrode surfaces should be flat and well aligned. Class 2 copper alloy electrodes, such as copper/chromium/zirconium, may be used but harder, tungsten/copper inserts are normally used to minimise wear of the electrode surfaces.