Conventional solid welding wire is copper plated on the surface of the semi-finished wire to enhance the conductivity and corrosion resistance of the wire and nozzle and to reduce the friction with the feed hose or nozzle. The plating thickness of copper-plated wire is generally 0.2 to 0.8 μm. During the welding process, a portion of the copper element melts into the weld, reducing the mechanical properties of the weld, especially low-temperature impact toughness and elongation. Copper will also oxidize into copper particles and escape into the air, which is harmful to human health when inhaled. The production of copper-plated wire also generates waste acid, which pollutes the environment. For these reasons, non-copper or Non Copper Coated Welding Wire has become popular and is favored by welders. Here, we will describe how to produce Non Copper Coated Welding Wire.
History of Non Copper Coated Welding Wire
ESAB Sweden started developing Non Copper Coated Welding Wire in 1997 when it was first named ECOIG and later renamed Autrod. In 2002, ESAB invented a Non Copper Coated Welding Wire using Advanced Surface Treatment (ASC) technology and named it Aristorod. this treatment darkens the surface of the wire or adds a protective layer to the surface while maintaining a surface finish that gives it It has been widely used in various fields because of its good electrical conductivity, wire feeding stability, rust resistance and welding performance.
Since 2002, Kobe Steel and Sumitomo Metal Industries, Ltd. have also offered a range of copper-free solid core wires for MAG and CO2 welding. Kiswell Korea has also patented the invention of a Non Copper Coated Welding Wire that uses a surface treatment oil containing alkali metal or alkaline earth metal compounds, zinc compounds and hydrocarbons to coat the surface of the wire with a strictly controlled amount of coating (0.003 to 0.006g for 1kg of wire).
Some scholars in Japan have proposed that the wire surface coated with MoS2, WS2 or C can improve wire feeding; some have proposed to cover the wire with potassium compounds, sulfur compounds, and polyisobutylene to reduce spatter; some patents have proposed to use a mixture of hydrocarbon mineral oil and vegetable oil, as well as a mixture of MoS2, WS2, C, PTFE, fatty acids, and metal soap to cover the wire to produce Non Copper Coated Welding Wire.
How is Non Copper Coated Welding Wire produced?
A. The hard fatty acid lubrication process
Stearate lubricant metal soap extreme pressure agent and rust inhibitor, and a certain amount of zinc, copper, aluminum, titanium and other metal powder mixed into lubricating particles for wire drawing. The particle size of metal powder is not more than 325#, and the mass fraction is generally about 10% (up to 30%) so that the total mass of lubricant attached to the wire surface is about 0.01%~0.25 % silk, and the metal powder is 0.001%~0.10%.
B. Water-soluble liquid lubricant process
Water-soluble liquid lubricant is suitable for low-hydrogen welding wire. Firstly, the semi-finished wire is electrolytically pickled with a 15%~25% H2SO4 solution.
Next, the cleaned wire is pulled out 1 to 2 times at a compression rate of 5% to 25%. The wire drawing lubricant consists of water-soluble sodium soap and a water-soluble inorganic antirust agent. Typical formulations are 0.75% and 0.75% mass fraction of sodium triglyceride hard fatty acid and sodium chromate respectively, the rest is water, and the volume fraction of rust inhibitor is 0.3% to 1.5%.
C. Surface coating process
The surface coating of the welding wire should be rust and moisture resistant, without destroying the stability of the arc and the metallurgical properties of the weld.
Ultra-fine graphite, molybdenum disulfide, fluorine resin without hydrogen as a surface treatment agent for welding wire or trichloroethylene or carbon tetrachloride as a solvent, and add a small amount of CeO2, K2CO2, CsCO3 as an arc stabilizer to improve the performance of the wire can be as needed. Some companies use Nashik rust inhibitor coating to make copper-free welding wire. The rust prevention mechanism is a single molecular deposit layer adsorbed on the metal surface, blocking the action of microcells in the atmospheric environment on the metal surface and inhibiting the occurrence of electrolytic corrosion.
Advantages of copper-free welding wire
The Non Copper Coated Welding Wire is a wire with a special surface treatment. By omitting the copper plating process, pollution is reduced and welders can prevent themselves from the haze of copper from the container. It is a new product to protect the global environment and human health.
1. Reliable arc stability
The average fall short circuit frequency is shorter than that of copper-plated welding wire. It can withstand drastic changes in the extension length of the welding wire.
2.Less spatter Small melt drops at the tip of the wire and less spatter. Even with high current welding, the amount of spatter can be controlled.
3. Wide range of welding current and voltage.
4. Stable findability
The welding gun hardly vibrates during welding, and there is no clogging caused by copper chips, which ensures long-term stable feed ability.
5. Good re-arc performance
When the arc is cut off, no large round droplets appear at the tip of the welding wire. The droplet diameter is small and easy to restrike.
6. Excellent anti-rust performance
Due to the new surface treatment technology, there is no need for copper plating, we can achieve better anti-rust performance than copper-plated welding wire.
7. Less smoke
The operating environment can be greatly improved because there is no copper coating and almost no copper fog. Therefore, the output of total smoke is reduced.
8. Less wear on the torch tip
Welding experiments show that the weld formation quality of the Non Copper Coated Welding Wire is significantly better than that of copper-plated wire.
Non Copper Coated Welding Wire shows a series of advantages in the welding process such as less welding fumes, less welding spatter, good stability of welding arc, good weld forming, etc. It is an environmentally friendly and economical new product, which has been widely used in machining, construction engineering, aerospace, bridge engineering, steel structure processing, etc. It can be considered as the development direction of solid wire.
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