1、 Core steps: Deduce specification parameters from requirements

1. Determine the matching between welding current and cross-sectional area

• Current determines the lower limit of cross-sectional area：
  The cross-sectional area of the welding wire should be selected according to the rated output current of the welding machine, ensuring that the current carrying capacity is ≥ the actual operating current. The following is an experience matching table:

• Verification method：

• Measure the DC resistance of the wire core with a multimeter (at 20 ℃, the resistance of 25mm ² pure copper wire is ≤ 0.07 Ω/100m). If the resistance is too high, it may be due to false cross-sectional area or poor material quality;

• Weighing comparison: A 100m long 25mm ² pure copper wire weighs approximately 22.25kg (copper density 8.9g/cm ³). If the weight is significantly lighter, it may be due to copper-clad aluminum or insufficient cross-sectional area.

2. Match the rated voltage with the operating voltage

• The voltage parameter must be ≥ the output voltage of the welding machine：
  The output voltage of the welding machine is usually 20-40V (about 60-80V under no-load), but the rated voltage of the welding wire needs to be ≥ 1000V (industrial scenario) or ≥ 500V (civilian scenario) to meet insulation safety requirements. For example:

• It is recommended to choose a welding wire with a rated voltage of 1000V for industrial grade welding machines (such as submerged arc welding machines);

• Household 220V welding machines can choose products with a rated voltage of 500V, but it is necessary to ensure that the insulation layer thickness is ≥ 0.8mm.

• Easy judgment of withstand voltage test：
  Use an insulation resistance meter (megohmmeter) to measure the resistance between the wire core and the insulation layer. At room temperature, it should be ≥ 100M Ω. If it is lower than 10M Ω, the insulation performance is not qualified.

2、 Environmental parameter adaptation: temperature resistance, weather resistance, and protection

1. Temperature resistance level matches the operating temperature

• Select insulation material based on welding scene temperature：

  insulating material	Temperature resistance range	Applicable scenarios	identification method
  Ordinary PVC	-15℃~60℃	Room temperature, no high temperature environment	Ignite and emit black smoke with a pungent odor
  neoprene	-30℃~80℃	Welding slag splashing scene (such as manual arc welding)	Ignite and self extinguish, with a mild odor
  silicone rubber	-60℃~200℃	High temperature environment (such as welding in front of the furnace)	After ignition, it turns into white ash without any sticky residue

• Risk of insufficient temperature resistance：
  If the surface temperature of the welding wire exceeds the upper limit of the insulation layer's temperature resistance during welding (such as silicone rubber exceeding 200 ℃), the insulation layer will soften and adhere, and even cause a short circuit.

2. Adaptation of weather resistance parameters to special environments

• Outdoor/industrial scenes require additional attention：

• Oil resistant typeIn oily environments (such as auto repair shops), a mineral oil resistant nitrile rubber insulation layer should be selected. A few drops of engine oil can be dripped onto the insulation layer, and after 24 hours, observe for expansion and cracking;

• 耐酸碱型Fluorine rubber insulation layer should be selected in the chemical workshop, and the surface can be wiped with hydrochloric acid. If discoloration or corrosion occurs, it is unqualified;

• Weather resistant typeChoose an insulation layer with added anti UV additives for outdoor operations, which can pass the sun exposure test (no cracks in the insulation layer after 1000 hours of light exposure).

3、 Verification of Core Material and Structural Parameters

1. Identification of pure copper material

• Appearance and physical characteristics：

• Core color: Pure copper is purple red, brass is yellowish, and the core of copper-clad aluminum is silver white after cutting;

• Bending test: The pure copper wire core is repeatedly bent 10 times without breaking, while the copper-clad aluminum wire is bent 3-5 times before breaking.

• Conductivity efficiency test：
  Take a 10m long soldering wire and apply 100A current for 30 minutes. The temperature of the pure copper wire core should be ≤ 60 ℃. If it exceeds 80 ℃, it may be due to poor material quality or insufficient cross-sectional area.

2. Structural parameters (hardness, bending radius)

• Priority given to multi strand thin copper wire structure：
  High quality welding wire is made of multiple stranded copper wires (such as a 25mm ² wire core consisting of 133 0.5mm copper wires), with good flexibility and a bending radius of ≤ 10 times the wire diameter, suitable for complex positional welding;

• Poor quality products may use a small number of thick copper wires (such as only 30 0.8mm copper wires per 25mm ²), which are prone to breakage and increased resistance when bent.