An In-Depth Guide to Projection Welding Assemblies - Based on Chinese Industry Practices

Projection welding is a highly efficient welding method capable of performing multiple welds simultaneously, replacing arc welding, brazing, and clinching. The principle is to pre-machine raised points on the sheet metal, or to utilize current-concentrating surfaces or chamfers on the weldment as contact points during welding. This contact point increases the pressure and current density per unit area, helping to break the oxide film on the sheet metal surface, concentrate heat, and reduce shunting. Projection welding is a variation of spot welding, primarily used for Projection Welding Assemblies made of low-carbon and low-alloy steel. The optimal thickness for projection welding is 0.5-4mm.

The production process for projection welding assemblies primarily includes the following steps:

Workpiece Preparation: First, clean the base metal of the Brazed Contact Assembly to remove impurities such as oil, rust, and moisture to ensure weld quality. Furthermore, based on design requirements, one or more raised points are machined on the mating surfaces of one workpiece, or current-concentrating surfaces or chamfers are utilized on the weldment itself.

Assembly and Positioning: Assemble and position the processed workpiece of the Resistance Brazing Electrical Contacts according to design requirements. Use fixtures or templates to ensure accurate workpiece alignment, reduce welding deviation, and improve production efficiency.

Welding Process: The projection welding process for Low Voltage Electrical Contacts can be divided into three stages: pre-pressing, heating, cooling, and crystallization. During the pre-pressing stage, electrode pressure increases the contact surface between the projection and the lower plate, breaking the oxide film on the contact surface and establishing good physical contact. During the heating stage, the projection collapses and the two plates are bonded, forming a large heated zone. As heating continues, melting at individual contact points gradually expands, forming a molten core and plastic zone of sufficient size. During the cooling and crystallization stage, after the welding current is cut off, the molten nugget begins to crystallize under pressure.

Quality Inspection: After welding is completed, the Spot Welding Assembly (as a type of projection-welded assembly) requires quality inspection. These include visual inspection to check for surface defects such as cracks, pores, and inclusions in welded joints; strength testing of welded joints, testing their strength and toughness through tensile and torsion tests; and dimensional measurement of welded joints, measuring joint dimensions such as bump height and spacing to ensure they meet specified requirements. X-ray and ultrasonic methods can also be used to inspect welded joints for internal defects.

Projection welding assemblies have significant advantages:
High Efficiency: They can perform multiple welding points simultaneously, greatly improving production efficiency and meeting the needs of large-scale production.

Good Welding Quality: The concentrated current, pressure, and heat facilitate the formation of a high-quality weld nugget, resulting in high strength and toughness in the weld joint, ensuring Projection Welding Assemblies.

Capable of Welding Special Structures: They can weld Brazed Contact Assembly with large thickness differences and can also be used to weld areas that are difficult to weld using other welding methods, such as grid structures and intersections.

Long Electrode Life: When using flat electrode projection welding, the part surface is smooth and free of craters, resulting in minimal electrode wear and a relatively long life.

However, projection welding assemblies also have certain limitations:
Additional Processing: Forming one or more projections on a workpiece often requires additional processing, unless the Resistance Brazing Electrical Contacts can be press-formed to the desired shape. This can increase production costs.

High Precision Requirements: When welding multiple joints simultaneously with the same electrode, workpiece alignment and projection dimensions, particularly height, must be controlled within tight tolerances to achieve uniform weld quality, placing high demands on machining and assembly precision.

Limited Protrusion Distribution: When simultaneously projecting multiple joints, the distribution of projections is limited by the current flow path, which may not always correspond to the desired position, potentially impacting welding results and Low Voltage Electrical Contacts design.

In automobile body manufacturing, projection welding nuts and bolts are often welded onto thin plates to facilitate subsequent assembly and improve efficiency. Spot Welding Assemblies are also used in the welding of components such as seats, instrument panels, fuel tank reinforcements, shock absorber brackets, and oil filters.

In the aerospace industry, projection welding is used to join high-strength alloy materials and manufacture key structural components of aircraft and spacecraft, such as frames and connectors. Projection welding ensures the weld quality and strength of these Brazed Contact Assemblies while meeting the lightweighting requirements of the aerospace industry.

In the electronics industry, projection welding is used to weld electronic components, circuit boards, and other parts. For example, attaching small electronic components to circuit boards using the projection welding process improves welding precision and reliability, ensuring the stable performance of Resistance Brazing Electrical Contacts.

In the home appliance manufacturing industry, Low Voltage Electrical Contacts are also used to weld certain components of appliances, such as refrigerators, washing machines, and air conditioners. Furthermore, projection welding assemblies have certain applications in the welding of metal components in the construction industry and in shipbuilding.

Our Projection Welding Assemblies utilize advanced design concepts and high-precision manufacturing processes to ensure that each component delivers optimal performance in real-world applications. From electrode material selection to the precision of the bump machining, every detail undergoes rigorous quality control. These components are perfectly compatible with a variety of welding equipment, easily handling diverse processes such as single-point projection welding, multi-point projection welding, and girth welding, providing stable and reliable support for your production.