Percussion welding was invented by doctor Lewis Warrington ChubbPercussion welding is a type of resistance welding process wherein Coalescence is produced by high-temperature heat obtained from an arc.
The arc is produced by a rapid discharge of electrical energy. And the pressure is (rapidly) applied during or immediately after an electrical discharge.
Percussion welding is accomplished in the following steps:
First of all, the workpiece is freed from grease, dirt, paint, etc., then the workpiece is clamped in a machine or fixer, then the two ends of the workpiece to be joined are brought together using light force. thereafter, the arc is struck between the faces of the workpiece, using several methods such as
- The workpiece is brought into light contact to establish the flow of current. Then the workpiece is pulled back to draw the arc,
- By cutting one of the pieces to form a nib of a smaller cross-sectional area, as current flows through the nib, the nib explodes thereby establishing an ionized path for the welding current to flow.
See More: Welding Arc establishment
- In another method, when sufficient DC voltage is applied, the air gap between the workpieces is neutralized and the current begins to flow
- Another method is also used to generate an arc, in which an auxiliary high-frequency, high-voltage AC is superimposed on a low-voltage current in the gap between the workpieces. Here high-frequency AC ionizes the air in the gap and maintains the low-voltage DC arc.
The arc is produced using one of the above methods and is heated to join the faces of two workpieces.
Power supplies for percussion welding are as follows:
|Low voltage (D.C)||10-150 Volts||Capacitive storage|
|High voltage (D.C)||1000-6000 Volts||Capacitive storage|
|Electromagnetic or inductive storage|
|Low voltage (A.C)||10-35 Volts||Uses a transformer to furnish|
The following types of metals can be welded by percussion welding
- Copper to Molybdenum Stainless steelsLow carbon steelsAluminum alloysMedium Carbon steelsNickel alloysCopper alloys
Applications of percussion welding
The use of percussion welding is as follows:
- On the attachment of metal tips to valve stems.
- It is used to make large contact assemblies for relays.
- With the help of percussion welding, even those materials (similar and dissimilar) can be joined which are impracticable to joint with flash or stud welding.
- This process is particularly capable of welding fine wire to the filaments of lamps.
- The terminals of electrical and electronic components can also be welded by the percussion welding process.
Due to the short arc in percussion welding, the fusion is confined to the surface of the part to be welded and is not disturbed by flash, etc.
A great feature of this process is that it does not destroy the heat-treatment of heat-treated or cold-worked metals.
Despite these features, it also has some limitations such as:
Only butt joints can be satisfactorily welded by percussion welding processes. and over 3 square cm, welding is difficult due to the difficulties of controlling the path of the arc.
Percussion welding is widely used in modern and commercial organizations. Continuous welding production can be achieved using this method.