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4. Suggested Settings for MMA Welding
5. Possible Welding Deficiencies
The following deficiencies are related to situations outside the electronic circuits
and are mostly attributed to accessories, gas and power supply and external
circumstances. These can be circumvented by controlling the environmental
factors.
5.1 Blackened Welding Spots
This phenomenon indicates that the welding spot is oxidised owing to insufficient
protection. The following remedial actions can be pursued:
5.1.1. Check the efficiency of gas flow and pressure. As a general rule the
pressure in the cylinder should be above 0.5 mPa. If not, exchange or
refill the cylinder.
5.1.2. Check the gas flow and ensure there is sufficient flow rate shielding for
the job at hand. The flow rate should never be below 3 l/min.
5.1.3. Ensure that the gas flow to the torch is unobstructed.
5.1.4. Ensure that the gas being used is correct and of good quality.
5.1.5. Strong air flow in the welding environment may influence gas shielding.
5.2. Difficult Arc Start or Easy Arc Break.
5.2.1. Only use a good quality electrode to meet the requirements for
high-quality welding.
5.2.2. Ensure that electrodes are sufficiently dried. Electrodes with a too high
moisture content will cause arc instability, welding defects and poor
welding quality.
Electrode diameter
（
mm
）
Welding current range
（
A
）
Welding Voltage range
（
V
）
Φ2.5
50~90
22.0~23.6
Φ3.2
90~130
23.6~24.2
Φ4.0
140~210
24.4~25.2
Φ5.0
200~260
26.4~28.4
Φ
6.0
260-300
28.0~30.8
