Capacitor welding

 Capacitor welding refers to contact welding. It is a type of pressure welding. The name capacitor welding  This indicates that this welding method accumulates energy in capacitors as they are charged by a voltage source. Then, during the discharge process, this energy is converted into heat, which is used for welding. When current flows, this heat is released at the contact between the workpieces, and the parts are joined.

Capacitor-controlled spot welding

Capacitor-controlled spot welding  The technique originated in the late 1930s. Initially, it was used to connect fasteners such as studs, grounding tabs, and bushings. Later, after refinement, it began to be used to connect small parts to thin metals.

Capacitor-controlled spot welding  It is successfully used in instrument making and, subsequently, in electronic components. When welding parts this way, the smaller cross-section part plays a significant role. It must meet the operating requirements of the welding machine. The other workpiece may have different thicknesses. This allows for a broader range of applications for capacitor discharge welding. Capacitor-controlled spot welding  Ideal for joining small parts on thin metal, this method maintains high connection quality, productivity, and significant cost-effectiveness.

Capacitor spot welding circuit diagram

Capacitor spot welding circuit diagram  The execution of the technological process includes the following main steps:

• The surface of the parts to be welded is prepared. A special requirement is the presence of an axial protrusion in the form of a cylinder with a diameter of 0.6–0.75 mm and a height of 0.55 mm to 0.75 mm. This allows for precise determination of the exact location of the stud weld to the metal. It also facilitates ignition and ensures stable arc burning across the surface of the part being welded.
• The parts are secured. The capacitors are discharged at a very high speed (1-3 ms);
• instant precipitation and hardening of the weld occurs.

The heat-affected zone (HAZ) with this welding method is minimal. The controlled energy input and upsetting process improve the quality of the welded joint.

Capacitor spot welding circuit diagram The connection can be transformer or transformerless.

1.  Transformer method.
2. This method provides the welding process with greater energy. This is facilitated by charging the capacitor at a higher voltage and discharging it through a step-down transformer, which generates higher welding currents.
3.  Transformerless method.
4. This method uses a simpler welding machine design. The capacitor is connected to the workpiece itself. A discharge occurs as the parts are joined. It melts the ends, which then causes the weld to collapse.

The disadvantages of this welding method are:

• need for special equipment;
• limitations of welded parts in the cross-section.

Key benefits:

• high speed of connecting parts;
• high performance;
• short pulse duration, which contributes to a minimal heat-affected zone;
• simplicity of the welding machine design;
• with a high welding current, the electrical network load is uniform.