CO2, MAG and MIG welding: Ideal current, wire diameter and plate thickness

1. The relationship between the commonly used manual steel arc welding current and the diameter of the welding rod, and the applicable range of plate thickness.

Instruction:

1. Low-alloy steels include heat-resistant steels and low-temperature steels (such as 15CrMo, 16MnDR).
2. For thicknesses greater than 4mm, a bevel must be opened, adopting a multi-layer and multi-pass welding process.
3. Low-alloy steel sheets with a thickness greater than 28 mm must undergo a preheating process to prevent the formation of cold cracks.
4. The purple copper plate must be preheated to 400 ~ 600 ℃ before welding.
5. For direct current, the workpiece is connected to the positive terminal, and for reverse polarity, the workpiece is connected to the negative terminal.
6. For root welding, a cellulose welding rod with direct positive connection is used, while for hot welding, filler welding and cover welding, a direct reverse connection is used.
7. The general welding speed range for manual arc welding is 2 ~ 15 cm/min.

2. The relationship between the commonly used carbon arc gouging current and the carbon rod, as well as the applicable range for plate thickness.

Instruction

1. Carbon arc gouging is used for gouging carbon steel, common low-alloy steel (such as 16Mn, 15MnV, etc.), stainless steel, heat-resistant steel and low-temperature steel. It is a process of chamfering, cleaning the back of welds and removing welding defects.
2. Carbon arc gouging must use a direct current power supply with reverse polarity (the workpiece is connected to negative).
3. The general planing speed ranges from 500 to 1200 cm/min.
4. Generally, for low-alloy steel sheets with a thickness of ≥30mm, a preheating process should be adopted before planing to prevent the steel from forming hardened structures and developing cold cracks.

3. The relationship between welding current and tungsten electrode diameter in tungsten inert gas (TIG) manual arc welding of commonly used material and the applicable range of plate thickness.

Instruction

1. The types of tungsten electrodes are thoriated and ceriated with a tip diameter of φ0.5, at an angle of 30 degrees. For AC welding, the diameter of the tungsten electrode tip is φ1.5, at an angle of 90 degrees.
2. For sheet metal thicknesses >4mm, a chamfer must be opened by adopting the multi-layer and multi-pass welding process. The preheating process must be applied to aluminum sheets with a thickness >8mm and copper sheets with a thickness >4mm. The welding speed for thin plates is 15 ~ 55 cm/min, and the automatic welding speed is 15-100 cm/min.
3. TIG welding is suitable for flat, vertical, horizontal and overhead welding in all positions.

4. The relationship between CO2/MAG/MIG welding current and wire diameter, as well as the applicable range for sheet thickness.

Instruction:

1. Short circuit transition is applicable for flat, horizontal, vertical and overhead welding positions; spray transition (droplet transition) is suitable for flat welding and fillet welding.
2. Low-alloy steel and austenitic stainless steel use flux-cored welding wire, resulting in good internal and external weld quality.
3. For sheets with a thickness greater than 6 mm, beveled edge welding is applied, using multilayer and multipass welding techniques. The maximum weldable thickness is 100 mm.
4. Preheating techniques must be applied to low alloy steel plates with a thickness of 28 mm or more and to aluminum and aluminum alloy plates with a thickness of 34 mm or more.
5. The general welding speed range for gas metal arc welding is 12-90 cm/min.:12-90 cm/min.

5. Recommended method for starting an arc and adjusting impulse current on a direct current arc welding machine.

Instruction:

1. The SS300, SS400, SS630 welding machines and the AT315 welding machine do not have an arc initiation current button.
2. TR315 tungsten electrode argon arc welding machine, when used for manual arc welding, allows adjustment of arc initiation and impulse current.
3. The numerical value of the arc impulse current (1/2, 1/3) indicates the clockwise rotation position of the knob.
4. The thrust current regulation is too high, causing the arc noise to be slightly louder and the splash of molten droplets to increase. Can be adjusted to zero when the rod is not clamped.

6. The actual load sustainability of various arc welding processes under different operating modes.

Instruction:

1. The selection of a welding machine is based on the thickness of the welded part, the welding position and the diameter of the welding material, to choose the maximum actual value of the welding current.
   Confirm the operation method and estimate the actual charging duration. When the actual charging duration exceeds the rated charging duration, the actual welding current should be lower than the rated current of the welding machine for normal use, to avoid damage to the welding machine.
2. For a CO2 welding machine rated at 200KR, the rated current is 200A when the duty cycle is 60%. When used for small batch continuous semi-automatic welding, the actual duty cycle is 60%, with a maximum welding current of 200A. During continuous automated large batch operations, the maximum allowable current value is 155A, which still satisfies the welding production of parts with a thickness of 6 mm.