Spot Welding is a process where the two welding metals are touched by electrodes from up and below, and while applying pressure, the running electric current produces heat melting and welding the metals.
Also, in cases where electrodes cannot be used such as welding the tab to batteries, as it is shown in the left circuit, R3 between tab plate and battery produces the heat needed for welding.. The welding quality is affected by factors such as welding current, flowing time, applied pressure, and welding materials. Welding current alters due to welding materials, surface condition, and pressure applied by the electrodes. In spot welding, the welding junction is called nugget; in order to get a good quality nugget, these factors need to be controlled. In addition, in order to ensure that the electrode itself does not weld, the electrode needs to release heat. A welder for professional welds a large number of identical materials in the same environment at high speed, thus these factors are optimally set. In comparison, a welder for personal use needs to handle different type and shape of materials. However, factors like electric current and pressure applied to electrodes, metal�fs conductivity and surface condition can be controlled easily through experience, so no concern is needed.
What are the materials possible to weld?
Spot Welding is a kind of "Resistance Welding". It runs electricity to the welding materials, then using the heat produced it melts the junction part of the metal. In brief, only materials that run electricity i.e. only metals are possible to weld.
Is it possible to weld any size of metal?
Within the car manufacturing wire, there is a robot welding things while sparks flying off all around. That is to say, using a large-scale welder, it is probably possible to weld any size of metal.
In consideration for safety, Yokodai.JP Spot Welder?which uses low voltage and small current?can only be used to weld thin metals.
As long as the metal is thin, is it possible to weld any kind of metal?
To produce heat from electricity, the metal needs to have a certain amount of resistance. In other words, metals which easily run electricity such as gold, silver, copper and aluminum are difficult to weld since the heat produced is too small. These kind of metals usually have a high heat conductivity, thus the heat is easily transmitted which becomes a factor that makes the welding even more difficult. If the current running through the thin metal is too big, the metal will be cut. Therefore it is important to adjust the flowing time and the current, also the pressure applied. Using Yokodai.JP Spot Welder, it is possible to weld 0.1 mm aluminum.
THE REASON WHY NICKEL AND STAINLESS STEEL ARE EASY TO WELD
Electric and Heat Conductivity for Metals at Room Temperature
Metal Name
Electric Conductivity
Heat Conductivity
W/(m K)
Gold
45.5
320
Silver
61.4
420
Copper
59.0
390
Aluminum
37.4
236
Phospate Bronze
13?15
133
Nickel
14.5
113
Stainless Steel
6-9
15-25
Iron
9.9
84
Metals with high electric conductivity have high heat conductivity too, so during spot welding, the heat escapes easily and this makes the welding more difficult.Spot Welding uses electric resistance to produce heat to weld, which is why rather than copper or silver which have good electric conductivity, metals which have resistance are easier to weld. Aluminum has an aluminium oxide layer on its surface which acts as insulator, thus it is difficult to weld with small current and low voltage.Also, if the heat escapes easily from the welding part, there will not be enough time to melt the metals. Thus it is better if the metals have low heat conductivity. However, as it is shown in the table on the left, electric and heat conductivity are closely related. Therefore, the metals which posses these two properties, such as Nickel and Stainless, are easy to weld.
