Resistance Welding Problems

Frequently Asked Questions About Resistance Welding

Resistance welding is a method of combining the workpieces, applying pressure through the electrodes, and using the resistance heat generated by the current passing through the contact surface of the joint and the adjacent area for welding. Resistance welding is a method in which current flows through the contact surface of the workpiece and the adjacent area to generate resistance heating effect, heat it to a molten or plastic state, and form a metal bond. ERW pipe is a steel pipe rolled by electric resistance welding process.

1. Splash
If the heating is too fast, and the surrounding plastic ring has not yet formed or is not tight enough, the sharply heated contact point will heat up extremely quickly. The internal metal is vaporized, and under the action of the electrode pressure, the liquid metal in the ring will be pressed out, and then sprayed to the plate gap in the form of splash, which is called internal splash Reason:
1) The surface of weldments and electrodes is not clean and there is a lot of dirt;
2) Electrode pressure is too small
3) There is no real contact between the weldment and the electrode
4) Iron particles stick to the electrode surface
5) The assembly gap is too large, and the two contact surfaces of the workpiece are not smooth
6) The workpiece is not clean
7) The shape of the electrode contact surface is incorrect
8) Preload time is too short
9) Excessive current
10) The workpiece is placed unevenly or tilted during welding
11) Small profits.
After the smallest nugget is formed, heating is continued, and the nugget and plastic ring continue to expand outward. When the radial expansion speed of the nugget is greater than that of the plastic ring, it will fly out. The reason for this is:
1) The welding current is too large;
2) The welding time is too long.
This is due to the strong electrode pressure breaking the plastic ring around the core, causing the liquid metal to overflow.

2. Welding
Cause:
1) The voltage is too low, and the magnetic material enters the secondary circuit of the welding machine;
2) The dot pitch is too small;
3) The current is small and the electrode pressure is large;
4) The diameter of the electrode end face is large;
5) Electrode surface wear and accumulation;
6) The welding time is insufficient and the welding specification is too strong.

3. Solder punch-through
Cause:
1) The current is too large;
2) Insufficient electrode pressure;
3) The boot time is too long;
4) Poor electrode cooling conditions;
5) The heating time is too fast

4. Solder joint indentation depth
Cause:
1) The startup time is too long;
2) Insufficient electrode pressure;
3) The current is too large;
4) The solder joint is seriously overheated;
5) Vigorous spraying;
6) The original size of the welding workshop;
7) The electrode is too sharp (the diameter of the electrode end face is too small)
The depth of electrode indentation on the surface of normal solder joints should not exceed 10%-20% of the plate thickness

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