How Do I Choose the Best Used TIG Welder?

TIG welding (Tungsten Inert Gas Welding), also known as non-melting extremely inert gas shielded arc welding. Whether it is manual welding or automatic welding of stainless steel with a thickness of 0.5 to 4.0 mm, TIG welding is the most commonly used welding method. The method of using TIG welding and filling wire is often used for bottom welding of pressure vessels, because TIG welding has better air tightness and can reduce the porosity of the weld seam during pressure vessel welding. The heat source of TIG welding is DC arc, the working voltage is 10 ~ 95 volts, but the current can reach 600 amps. The correct connection method of the welding machine is that the workpiece is connected to the positive electrode of the power source, and the tungsten electrode in the welding torch is used as the negative electrode. The inert gas is generally argon.

Gas shielded welding is an arc welding method using an external gas as a protective medium. Its advantages are good visibility of the arc and the molten pool, and easy operation; no slag or very little slag, and no slag removal after welding is required. However, special outdoor wind protection measures are required when working outdoors.

According to whether the electrode is melted during welding, gas shielded welding can be divided into non-melting electrode (tungsten) gas shielded welding and molten electrode gas shielded welding. The former includes tungsten inert gas shielded welding,

Tungsten arc welding is divided into manual welding, semi-automatic welding and automatic welding according to the operation mode. During manual TIG welding, the movement of the welding torch and the addition of the filler wire are completely manually operated; during semi-automatic tungsten arc welding, the welding torch movement is manually operated, but the filler wire is automatically fed by the wire feeding mechanism; automatic tungsten electrode In arc welding, if the workpiece is fixed and the arc moves, the welding gun is installed on the welding carriage, and the walking and filling of the welding wire can be added by cold wire or hot wire. Hot wire means increasing the welding speed. In some cases, such as sheet welding or undercut welding, sometimes it is not necessary to add filler wire.

Of the three welding methods mentioned above, manual TIG welding is the most widely used, and semi-automatic TIG welding is rarely used.

1, will produce DC components

When alternating current welding metals such as aluminum and magnesium, the electron emission capabilities of tungsten electrodes and aluminum, magnesium, and other workpieces are different. Tungsten electrodes have a stronger ability to emit electrons when used as cathodes. In the positive half cycle, the tungsten electrode is used as the cathode. The number of electrons in the arc space increases and the conductivity is easy, which is equivalent to the reduction of the equivalent resistance of the arc. Therefore, the arc current increases under the same power source. . Because the current in the two half cycles is asymmetric, the current of the AC arc can be regarded as consisting of two parts, one is the direct current, and the other is the direct current superimposed on the alternating current part. This part of the direct current is called the direct current component, and its direction is within the positive half cycle. The current flows in the same direction from the base material to the tungsten electrode. This phenomenon of generating a DC component in an AC arc is called the "rectification effect" of tungsten-pole AC argon arc welding. Generally, the greater the difference in physical properties between the two electrode materials, the greater the DC component. The appearance of the DC component will weaken the crushing effect of the cathode and affect the normal operation of the welding transformer, so it is necessary to eliminate the DC component.

Inserting a reverse polarity battery and an isolation capacitor in the welding circuit can eliminate the DC component. The direction of the current generated by the battery is opposite to the direction of the DC component. The capacitor only allows AC to pass but DC cannot pass. In terms of arc stabilization, a high-frequency oscillator is used to stabilize the arc or a high-voltage pulse is used to initiate and stabilize the arc.

2. Arc stabilization measures must be taken

Due to the problem of constant current commutation in the AC welding machine, whenever the current changes direction, there is no current flowing for a short period of time, causing the arc to be unstable or even extinguished, so the AC arc is not as stable as the DC arc.

Due to the protection of argon, the harmful effects of air on molten metals are isolated. Therefore, TIG welding is widely used for welding non-ferrous metals such as aluminum, magnesium, and their alloys, stainless steel, high temperature alloys, titanium and titanium alloys, which are difficult to oxidize. Molten active metals (such as molybdenum, niobium, zirconium, etc.), and general carbon steel, low alloy steel and other common materials, except for high welding quality requirements, generally do not use TIG welding.

GMT-SKD11> 0.5 ~ 3.2mm HRC 56 ~ 58 Welding cold work steel, metal stamping dies, cutting dies, tools, forming dies, and hard surfaces of workpieces to produce argon electrodes with high hardness, wear resistance and high toughness, welding Warm up and warm up before replenishing, otherwise cracking may occur.

GMT-63 degree edge welding wire> 0.5 ~ 3.2mm HRC 63 ~ 55, mainly used for welding broach die, hot work high hardness tool die, hot forging master die, hot die, screw die, wear-resistant hard surface , High speed steel, knife edge repair.

GMT-SKD61> 0.5 ~ 3.2mm HRC 40 ~ 43 Welding zinc, aluminum die-casting mold, good heat resistance and crack resistance, hot gas die, aluminum-copper hot forging mold, aluminum-copper die-casting mold, good resistance Heat, abrasion and crack resistance. In general, hot die casting molds often have tortoise shell cracks, most of which are caused by thermal stress, and also caused by surface oxidation or corrosion of die casting raw materials. Heat treatment is adjusted to an appropriate hardness to improve its life. Be applicable.

GMT-70N> 0.1 ~ 4.0mm welding wire characteristics and uses: bonding of high hardness steel, cracking of zinc-aluminum die casting mold, welding and reconstruction, pig iron / cast iron welding repair. It can directly overlay various cast iron / pig iron materials, and also can be used for welding of mold cracks. When using cast iron welding, try to keep the current as low as possible, use short-distance arc welding, and preheat the steel partly. It heats and cools slowly.

GMT-60E> 0.5 ~ 4.0mmCharacteristics and use: Special welding of high tensile steel, bonding of hard surface, cracking welding. High-strength welding wire, containing high content of nickel-chromium alloy, is professionally used for anti-cracking bottom welding, filling and priming, strong tensile force, and can repair cracks in steel after welding. Tensile strength: 760 N / mm & sup2; Elongation: 26%

GMT-8407-H13> 0.5 ~ 3.2mm HRC 43 ~ 46 Zinc, aluminum, tin and other non-ferrous alloys and copper alloy die-casting dies, can be used as hot forging or stamping dies. With high toughness, abrasion resistance and thermal erosion resistance, high temperature softening resistance, good high temperature fatigue resistance, can be used for heat treatment of punches, reamer, rolling knife, grooving knife, scissors ... When it is necessary to prevent decarburization, the hardness of the hot tool steel after welding is too high and cracks will occur.

GMT-Explosion-proof cracking welding wire> 0.5 ~ 2.4mm HB ~ 300 Bonding of high-hardness steel, making of hard surface, cracking welding. High-strength welded branch with high content of nickel-chromium alloy. It is used for anti-cracking bottom welding, filling and priming, strong tensile force, and can repair crack welding and reconstruction of steel.

GMT-718> 0.5 ~ 3.2mm HRC 28 ~ 30 Large household appliances, toys, communications, electronics, sports equipment and other plastic product mold steel. Plastic injection mold, heat-resistant mold, anti-corrosion mold, good machinability, erosion resistance, excellent surface gloss after grinding, and long service life. The preheating temperature is 250 ~ 300 , and the hot temperature is 400 ~ 500 . When multi-layer welding is used, the welding method of backward method is used, which is less likely to cause poor fusion and other defects.

GMT-738> 0.5 ~ 3.2mm HRC 32 ~ 35 Plastic mold steel for translucent and surface gloss, large mold, plastic mold steel with complex shape and high precision. Plastic injection mold, heat-resistant mold, anti-corrosion mold, good etch resistance, excellent processing performance, easy cutting and polishing and electrical corrosion, good toughness and wear resistance. The preheating temperature is 250 ~ 300 , and the hot temperature is 400 ~ 500 . When multi-layer welding is used, the welding method of backward method is used, which is less likely to cause poor fusion and other defects.

GMT-P20Ni> 0.5 ~ 3.2mm HRC 30 ~ 34 Plastic injection mold, heat-resistant mold (cast copper mold). Designed with alloy components with low sensitivity to welding cracking, containing about 1% nickel, suitable for PA, POM, PS, PE, PP, ABS plastics, with good polishability, no pores and cracks after welding, good after grinding The finish is vacuum degassed. After forging, it is pre-hardened to 33 degrees HRC, the hardness of the cross-section is uniform, and the life of the mold is more than 300,000. The preheating temperature is 250 ~ 300 , and the hot temperature is 400 ~ 500 . When multi-layer welding is used, the welding method of backward method is used, which is less likely to cause poor fusion and other defects.

GMT-NAK80> 0.5 ~ 3.2mm HRC 38 ~ 42 Plastic injection mold, mirror steel. High hardness, excellent mirror effect, good discharge processability, excellent welding performance. After grinding, it is as smooth as a mirror. It is the most advanced and best mold steel in the world. With the addition of free-cutting elements, it is easy to cut and has high strength, toughness and resistance. Grinding without deformation, suitable for mold steel of various transparent plastic products. The preheating temperature is 300 ~ 400 , and the hot temperature is 450 ~ 550 . When used for multi-layer welding, the welding method using the back-up method is less likely to cause defects such as poor fusion.

GMT-S136> 0.5 ~ 1.6mm HB ~ 400 plastic injection mold, good corrosion resistance and permeability. High purity, high mirror degree, good polishing, excellent rust and acid resistance, few heat treatment variations, suitable for PVC, PP, EP, PC, PMMA plastics, corrosion-resistant and easy-to-process modules and fixtures, super mirror-resistant Precision molds, such as rubber molds, camera parts, lenses, watch cases, etc.

GMT- Ace of steel> 0.5 ~ 2.4mm HB ~ 200 iron mold, shoe mold, soft steel welding, easy to engraved corrosion, S45C, S55C steel and other repairs. The texture is fine, soft, easy to process, and there will be no pores. The preheating temperature is 200 ~ 250 , and the hot temperature is 350 ~ 450 .

GMT-BeCu (Beryllium Copper)> 0.5 ~ 2.4mm HB ~ 300 Copper alloy mold material with high thermal conductivity, the main additive element is beryllium, which is suitable for the inner inserts, cores, die-casting punches, heat flow of plastic injection molding molds Cooling system, thermal nozzle, integral cavity of blow mold, wear plate, etc. Tungsten copper materials are used in resistance welding, electrical sparks, electronic packaging, and precision mechanical equipment.

GMT-CU (argon-welded copper)> 0.5 ~ 2.4mm HB ~ 200 This welding support is widely used for welding repairs of electrolytic sheets, copper alloys, steel, bronze, pig iron, and general copper parts. Good mechanical properties, can be used for copper alloy welding repair, but also used for welding steel and pig iron, iron joints.

GMT-oil steel welding wire> 0.5 ~ 3.2mm HRC 52 ~ 57 Punching die, gauge, drawing die, perforated punch, can be widely used in hardware cold stamping, hand decoration embossing die, general special tool steel, wear-resistant ,Oil cooler.

GMT-Cr steel welding wire> 0.5 ~ 3.2mm HRC 55 ~ 57 punching die, cold forming die, cold drawing die, punch, high hardness, high ductility, good wire cutting. Warm up and warm up before welding, please do post-heating after welding.

GMT-MA-1G> 1.6 ~ 2.4mm, ultra-mirror welding wire, mainly used in military products or extremely demanding products. Hardness HRC 48 ~ 50 Maraging steel, aluminum die-casting die, low-pressure casting die, forging die, blanking die, injection molding die. Special hardened high-toughness alloy, very suitable for aluminum gravity die-casting molds, gates, and prolonging the service life by 2 ~ 3 times. It can produce very precise molds and super-mirror surfaces (gate repair welding, not easy to use thermal fatigue cracks).

GMT-high speed steel welding wire (SKH9)> 1.2 ~ 1.6mm HRC 61 ~ 63 high speed steel, durability is 1.5 ~ 3 times that of ordinary high speed steel, suitable for manufacturing and processing high temperature alloy, stainless steel, titanium alloy, high strength steel, etc. Tools for processing materials, welding repair broaches, hot work high hardness tools, dies, hot forging master dies, hot stamping dies, screw dies, wear-resistant hard surfaces, high speed steel, punches, knives, electronic parts, thread rolling dies , Dental plate, drilling roller, rolling die, compressor blade and various mold mechanical parts, etc ... After strict quality control by European industrial standards, high carbon content, excellent composition, uniform internal organization, stable hardness, and wear resistance, toughness, high temperature resistance, etc ... The characteristics are better than ordinary materials of the same grade.

GMT-Nitrided Parts Welding Wire> 0.8 ~ 2.4mm HB ~ 300 Suitable for nitriding molds and parts surface repair.

The thorium tungsten electrode used in argon arc welding and plasma arc cutting contains 1-1.2% of thorium oxide. Thorium is a radioactive substance, which is affected by radiation during welding and contact with thorium tungsten rods.

Radiation acts on the human body in two forms: one is external exposure, and the other is internal exposure through the respiratory and digestive systems. A large number of investigations and measurements on argon arc welding and plasma arc welding have proved that their radioactive hazards are relatively small, because the thorium tungsten rod is consumed only 100-200 mg per day, and the radiation dose is minimal, which has little impact on the human body. .

There are two situations that must be paid attention to: First, when welding in the container, the ventilation is not good, and the radioactive particles in the smoke may exceed the hygienic standard; the second is when grinding the thorium tungsten rod and the place where the thorium tungsten rod exists, the radioactive aerosol and The concentration of radioactive dust can meet or exceed hygienic standards.

The invasion of radioactive substances into the body can cause chronic radioactive diseases, which are mainly manifested in the weakening of general functional conditions, and obvious signs of weakness, weak resistance to infectious diseases, and weight loss can be seen.