About MIG(MAG) Welding

    MIG (MAG) welding uses fusible welding wire as the electrode, and uses the arc burning between the continuously fed welding wire and the workpiece to be welded as the heat source to melt the welding wire and the base metal. During the welding process, the shielding gas-argon gas is continuously delivered to the welding area through the welding gun nozzle, so that the arc, the molten pool and the nearby base metal are protected from the harmful effects of the surrounding air. The continuous melting of the welding wire should be transferred to the welding pool in the form of droplets, fused with the molten base metal and condensed to form the weld metal.

    Carbon dioxide gas shielded arc welding is a method of welding with carbon dioxide gas as a shielding gas. In some special cases, a mixed gas of carbon dioxide and argon is used. The operation during use is relatively simple, suitable for automatic welding and omni-directional welding. However, because of the need for gas protection, the ability to resist wind is poor, so it is more suitable for operation in an indoor ventilated environment. Because carbon dioxide gas is easy to produce and the cost is low, carbon dioxide shielded arc welding is widely used in all walks of life. The use of high-quality welding machines and suitable welding parameters can achieve a very stable welding process, which greatly reduces spatter. Due to the low gas price and the good weld formation when short-circuit transfer is used, and the use of a wire containing deoxidizer can obtain high-quality welding results without pores and internal defects, this method has become the most important method for ferrous metals. One of the welding methods.

Early welding methods used carbon dioxide and water vapor as shielding gas, but the welding effect was extremely poor, and the metal was severely oxidized and formed many pores. Therefore, only inert gases such as argon and helium were used as shielding gases to solve the problem of non-ferrous metal welding in the aviation industry. However, helium and argon are very expensive as rare gases, and their application scale is quite limited. Therefore, after the re-study of carbon dioxide gas shielded welding in the later period, carbon dioxide gas shielded arc welding was gradually applied in welding production.


Advantages and disadvantages

1. High welding production efficiency. Because the welding current density is relatively large, the utilization rate of arc heat is high, the welding speed is fast, the requirements for operation technology are relatively low, and there is no need to clean up the welding slag after welding, so the production efficiency is very high. Compared with manual arc welding and argon arc welding, the welding speed increases by multiples.
2. The welding cost is very low, the carbon dioxide is easy to produce, the price is low, the power consumption is low, and the price of consumables is relatively lowest.
3. Achieve minimal deformation of the workpiece. Due to the small heating area of ​​the workpiece that is concentrated by arc heating, and the extremely low temperature produced by carbon dioxide in the liquid to gas state can quickly cool the workpiece, the deformation of the workpiece can be reduced to a minimum, which is very suitable for thin plate welding.
4. High welding quality. Low sensitivity to rust, low oxygen content in the weld, and good crack resistance.
5. The scope of application is extremely wide. It can be welded in all directions, from thin plates to medium and thick plates and even thick plates.
6. Simple operation. There is no need to clean up the welding slag after welding.


1. Compared with manual arc welding and argon arc welding, the spatter rate is larger, and the forming rate of the weld surface is poor.
2. It is difficult to use alternating current for welding, and the welding equipment is relatively complicated.
3. Poor wind resistance, outdoor operations may affect the welding effect due to wind speed.
4. Non-ferrous metals that are easily oxidized cannot be welded
The shortcomings of carbon dioxide gas shielded arc welding can be solved by improving the technical level, improving welding equipment and welding materials, but the advantage is that other welding methods cannot surpass. Therefore, carbon dioxide gas shielded arc welding is a high-efficiency low-cost high-quality welding method.


Due to the different forms of droplet transfer during CO2 gas shielded welding, different welding parameters need to be used.

1.Process parameters during short-circuit transition

1) Short-circuit transfer welding adopts thin welding wire, the commonly used welding wire is directly 0.6~1.2mm, and the spatter particles will increase as the diameter of the welding wire increases. The main welding parameters in short-circuit transfer welding are arc voltage, welding current, welding wire speed, gas flow, etc.
2) Arc voltage and welding current are the key parameters during short-circuit transition. The characteristic of short-circuit transition is the use of low voltage. The matching of arc voltage and welding current can reduce spatter and make the welding seam well formed. For example, the welding parameters of 1.2mm are generally voltage=19V, current=120~135A.
3) As the welding speed increases, the weld width, penetration depth and reinforcement are all reduced. If the welding speed is too low, it is easy to cause defects such as coarse burn-through structure and deformation, which reduces the quality and efficiency of welding. Therefore, the welding speed should be selected correctly according to the actual situation.
4) If the gas flow rate and purity are too small, the weld is prone to defects such as pores; when the gas flow is too large, it will not only waste gas but also increase the oxidation, and a dark gray oxide scale will form on the surface of the weld, which will reduce the quality of the weld. . In order to ensure that the welding area is free from air pollution, when the welding current is large or the welding speed is too fast, the welding wire extends longer and the gas flow should be increased during outdoor welding. Normally, the gas flow rate is between 15~25L/min during filament welding. The purity of CO2 gas shall not be lower than 99.5%. At the same time, when the pressure in the cylinder is lower than 1Mpa, stop using it to avoid pores. Because when the pressure in the cylinder decreases, the amount of moisture vaporized in Honor CO2 will also increase, so that too much water vapor will be mixed into the CO2 to affect the welding effect.
5) Since the short-circuit transition adopts thin welding wire, the resistance heat generated by the extension length of the welding wire has a great influence. The extension length increases, the resistance heat on the welding wire increases, the welding wire melts faster, and the productivity increases. However, when the extension length is too large, the welding wire is easy to overheat and melt in sections, causing serious spatter and unstable welding process. At the same time, the distance between the nozzle and the workpiece will increase after the extension increases, and the effect of gas protection will be reduced. However, if the extension length of the welding wire is too small, the distance between the nozzle and the workpiece will be shortened, and the splashed metal objects will block the nozzle and the protective nozzle. The proper extension length should be 10~12 times the diameter of the welding wire, and 8~15mm for the fine welding wire

2.The fine grain transition mostly uses thicker welding wire, 1.2mm or more.



How to choose a suitable MIG welding machine?

Maximum current and maximum welding thickness
The ampere output power of the MIG welding machine greatly determines the diameter of the welding wire that the machine can use, and also how thick the machine can weld the plate. However, the maximum welding thickness of welding wires of different materials is different when the same current is used. Because the characteristics of each metal are different, there will be some differences in the penetration of the plate under the same current and the same welding speed. For example, you can weld iron very quickly under the same current, but you need to reduce your welding speed when welding stainless steel, so you'd better use some tables to determine how many amperes of output power the plate you need to weld. Then decide that you want to buy the machine with the maximum output current.

Duty cycle
The percentage of the machine’s working time and rest time is called the duty cycle, which is usually calculated in the range of 10 minutes
For example, if the duty cycle of the machine is 60%, the machine can work for 6 minutes and can rest for 4 minutes within ten minutes. If the working time is less than 6 minutes in 10 minutes, it will help to extend the life of the machine.

If you are welding a piece of material with a very high thickness and close to the limit that the machine can weld, even if the machine is not overloaded, you need to pay attention to whether it is close to the rated working time. So as not to reduce the service life of the machine.

The rest time allows the machine to cool down, preventing the high temperature generated by the machine load from damaging the machine circuit and reducing its life.

Welding wire material and size compatible
At present, most of the machines with displays on the market will indicate the compatible welding wire material and welding wire diameter in the display. Some machines can use welding wire with embedded flux without using carbon dioxide gas protection. When the embedded flux burns, it will release shielding gas to protect the weld, replacing the external carbon dioxide gas. Its advantage is that it can avoid carrying gas cylinders, only need to carry flux-cored welding wire, and there is less spatter during welding, and the welding speed is 10% higher than that of solid welding wire. But the disadvantage is that you need to buy flux-cored wires of different materials according to the materials you need to weld. Moreover, when the flux-cored wire is burned, it will release a large amount of smoke and dust and leave welding slag. The price is relatively expensive in kilograms, and it is easy to rust and difficult to store. It is relatively difficult to feed the wire during welding. Therefore, a welding machine that can perfectly adapt to various materials and sizes is extremely important, and you can calmly cope with various work requirements.

Input voltage and portability
Many plasma cutting machines on the market have 220V models and 110V/220V models. If your local voltage is 110V, you must choose a machine that supports 110V voltage, but there is one thing to note, the amperage of the machine calibration is the amperage under the rated 220V voltage, so you must ensure the power generated by the machine under the 110V voltage Can also meet your work needs. .

If you are not using the machine in a fixed location in your personal workshop, the weight and portability of the machine are more important to the user of the machine.
If you carry this machine to and from different workplaces or residences, the machine is very portable and can perfectly adapt to the on-site power supply voltage, which is great! Both 110V and 220V can start to work.

Consumable specifications
Compared with other welding forms, the MIG welding machine needs to prepare relatively more consumables, so pay special attention to whether you can easily buy or prepare a sufficient number of adaptable consumables for replacement. For example, the welding wire of the same size as the internal spool of the machine, the nozzle of the welding torch, the wire feeding pipeline inside the welding torch, and various types of wire feeding rollers.


How to start MIG welding

When you buy a MIG welding machine that is completely suitable for you, you can start to learn how to weld. Compared with MMA or TIG, the technical requirements for this are not high, because as long as your current, voltage and welding wire match, you can complete the metal droplet transfer, but the difference is beautiful, there is almost no melting or adhesion. possibility. But you need some attempts to improve your welding skills. For example, you can find some metal scraps or scraps in local metal factories or some shops, and you can try welding with these materials. Contrary to plasma cutting, you need to start with a certain thickness of the plate, and gradually try to reduce the thickness of the plate after improving the technical and theoretical knowledge. If you want to get a perfect work then these attempts are indispensable.

Safety instructions
Although the output voltage of the electric welding machine is relatively low, the possibility of electric shock when using the machine is also very small. But if you get an electric shock, although it is not fatal, you will feel partly paralyzed. Moreover, it is very dangerous if it comes into contact with the power supply of the machine or the positive and negative poles of the output, which may endanger lives on the spot. Think about it, even metal can melt, let alone the body. Therefore, we must pay attention to prevent electric shock when operating the machine. Avoid using the welding machine when wet and sweaty and wearing insulated shoes and gloves. The most important thing is not to stand in the water. When starting the arc, you must wear appropriate DIN shading glasses or welding mask to avoid electrical burns. If you burn your eyes, you may experience tears for 2 to 3 days, inability to concentrate, and photophobia, which may cause permanent damage.

Splashes from welding machines can also cause great damage. For example, splashing sparks sometimes contain large particles of molten metal. Its temperature is very high and will penetrate your clothes and shoes and burn your body or scalp. The temperature of the workpiece will rise sharply during welding, and your hands may be burned during welding. Therefore, you must wear appropriate protective equipment when operating the MIG welder, such as welding gloves, boots, aprons or split protective clothing. Otherwise it will bring you great harm, so these protective measures are very necessary.

There are many safety matters to pay attention to, but at present I can only tell you some basic safety knowledge, but the one that will never go wrong is "obey the machine operation manual, standardize use from beginning to end, and comply with local work safety regulations."

Hope you learned about basic MIG welding in this article

MIG welding is very simple and easy to learn, you only need to prepare the machine and make a lot of attempts while complying with the safety regulations.
If you have never operated a MIG welder, you will not be able to weld a perfect weld in a short time. This requires you to practice a lot of scrap metal. But when you can weld a perfect weld under any circumstances, you will get a high salary, and a skilled welder's salary is not low!   




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