Copper wire is an essential auxiliary material used in the production of three-piece tinplate cans. During production, the wire runs in a special winding pattern between the upper and lower welding wheels of the resistance welding machine. The low-voltage, high-current passing through the copper wire welds the tinplate can body, with the copper wire serving mainly to:

1. Conduct welding current and pressure to the tinplate can body to perform the weld.
2. Carry away molten tin from the tinplate onto the copper wire to prevent tin contamination on the welding wheels.

Theoretically, copper wire has no consumption during the production of three-piece tinplate cans.

Copper wire used for can welding should meet the requirements of GB/T14251—1993. Globally, most copper wire manufacturers follow industry standards.

Pure Copper Round Wire for Can Welding
Copper wire used for welding three-piece tinplate cans should comply with the specifications in Table 2-29.

Item Require
1. Chemical requirements Comply with the relevant provisions of T2 in GB 5231-2001 Chemical composition and shape of processed copper and copper alloys
2. Finished product characteristics Brand: T2
Supply Status: Soft (M)
Diameter and tolerance
Wire diameter 1.38mm 1.5mm
Allowable deviation +0.01
-0.02		 +0.01
-0.02
Resistivity: at 20 degrees
Mechanical properties
Wire diameter /mm tensile strength (N/m2) Elongation CIP=100mm
1.3-1.5 225-265
Surface Quality
The wire surface should be smooth and clean, free of cracks, peeling, burrs, overstretching, folds, and inclusions. Minor localized imperfections such as indentations, spots, pits, and scratches should not exceed the allowable diameter and should not affect welding quality. Minor redness, darkening, oxidation, and minor localized water or oil stains that do not affect welding are not grounds for rejection. The wire ends should be tight, free of shrinkage, pores, delamination, and inclusions.
Wire out-of-roundness: Not exceeding the allowable diameter tolerance.
3. packing Wire barrel quality of wire barrel packaging
Wire diameter /mm The mass of each barrel is not less than /kg
1.3-1.5 Standard barrel Lighter barrel
140 100
Each batch of wire barrels can be delivered with a weight of no more than 10% lighter. Each barrel should not have more than two wire ends. The head and tail of the wire should be marked with “head” and “tail”.
*1.27mm copper welding wire has been used and the welding wheel needs to be repaired.

Table 2-29 Copper wire for welding tinplate three-piece cans