There are many types of copper wires on the market. Common ones can be divided into bare copper wire, tinned copper wire and copper clad aluminum wire. Bare copper wire is ordinary copper wire, also known as environmentally friendly copper wire. Many people are not very clear about the three types of copper wires. Let's take a look.

1. Bare copper wire
Bare copper wire is a copper wire made by drawing pure copper rods. It has a yellow appearance, a single material, copper metal inside and outside, and the color varies depending on the purity of the copper. In terms of physical properties, bare copper wire is soft and has excellent conductivity.

2. Tinned copper wire
Tinned copper wire is a pure copper rod drawn into wire and then a thin layer of tin is plated on the surface of the copper wire using a hot-dip tinning process. Because tin is a silver metal, the appearance of tinned copper wire is generally silver. Tinning copper wire is mainly to prevent copper from being exposed to the air and oxidized to form verdigris. Verdigris has poor conductivity and increases resistance. Tinned copper wire is relatively soft and has good electrical conductivity. Compared with bare copper wire, it has stronger corrosion resistance and oxidation resistance, which can greatly extend the service life of weak current cables. In addition, tinning of copper wire can also prevent the insulating rubber from becoming sticky, the wire core from becoming black and brittle, and improve its weldability.

3. Copper clad aluminum wire
Copper clad aluminum wire usually adopts cladding welding manufacturing technology, which concentrically wraps the copper strip on the outer surface of the aluminum rod core wire, and forms a strong metallurgical bond between the copper layer and the core wire, so that the two different metal materials are combined into an inseparable whole, which can be drawn and annealed like processing a single metal wire. During the drawing process, the copper and aluminum change diameters in the same proportion, and the volume ratio of the copper layer remains relatively constant. Copper clad aluminum wire is very light in weight. Compared with the previous two, it has much worse electrical conductivity, insufficient flexibility, easy to break, and relatively low corrosion resistance and oxidation resistance.

How to distinguish these three wires?

Appearance
Tinned copper wire is silver, bare copper wire and copper-clad aluminum wire are purple. Just cut a section vertically and neatly, and look at the cross section. If it is purple, it is copper wire; if it is white, it is copper-clad aluminum wire.

Tool scraping
Tinned copper wire appears purple after scraping, bare copper wire is still purple, and copper-clad aluminum mesh appears white with snowflakes. The same effect can be achieved by rubbing the copper wire on the cement floor.