How to weld wire harness

The traditional wire harness welding process includes: welding, soldering, and pressure welding.

(1) Welding is the method of heating the workpiece interface to the molten state during the welding process, without welding to complete the welding method. During welding, the heat source rapidly heats and melts the interfaces of the two workpieces to be welded to form a molten pool. The molten pool moves forward along with the heat source, forming a continuous weld seam after cooling and connecting the two parts together. After the welding, the harness joints are welded together to form welded joints. The resistance is large, which greatly reduces the service life of the harness. And in the welding process, if the atmosphere is in direct contact with the high-temperature molten pool, oxygen in the atmosphere will oxidize metals and various alloying elements. Nitrogen in the atmosphere, water vapor, etc. enter the molten pool, and defects such as pores, inclusions, and cracks are formed in the weld during subsequent cooling, which deteriorates the quality and performance of the weld.

(2) Brazing is the use of a metal material with a lower melting point than the workpiece as the brazing material. The workpiece and the brazing material are heated to a temperature higher than the melting point of the brazing filler metal and lower than the melting point of the workpiece. The workpiece is wetted with the liquid brazing filler metal, and the gap is filled. Interdiffusion of atoms with the workpiece to achieve the welding method.

The joint formed between two connected bodies at the time of welding is called a weld. Both sides of the weld are subjected to welding heat during welding, and changes in structure and properties occur. This area is called the heat-affected zone. Due to the difference in welding materials, welding currents, etc. of the workpiece materials during welding, the welded joints and heat-affected zones may be overheated, embrittled, hardened, or softened after welding, and the performance of the weldment may also be degraded, which may deteriorate the weldability. This requires adjustment of the welding conditions. Preheating before welding, heat preservation during welding, and heat treatment after welding can improve the welding quality of weldments.

(3) Pressure welding is under pressure conditions, so that the two workpieces in the solid state to achieve inter-atomic bonding, also known as solid-state welding. The commonly used pressure welding process is resistance butt welding. When the current passes through the connection ends of the two workpieces, the temperature rises due to the large resistance. When heated to the plastic state, the connection is integrated under the axial pressure.

A common feature of various pressure welding methods is the application of pressure during the welding process without the addition of filler material. Most pressure welding methods such as diffusion welding, high frequency welding, cold pressure welding, etc. have no melting process, and thus there is no problem of burning of the beneficial alloy elements such as welding, and the intrusion of harmful elements into the weld, thereby simplifying the welding process, and also Improved welding safety and hygiene conditions. At the same time, the heat affected zone is small because the heating temperature is lower than the fusion welding and the heating time is short. Many materials that are difficult to weld by fusion welding can often be pressure welded into high-quality joints with the same strength as the base metal.

In summary, pressure welding will inevitably replace fusion welding and fiber welding as the mainstream process of wire harness welding.