Capacitor Discharge (convex) Spot Welding Machine
Capacitor Discharge Convex Spot Welding Machine uses high-energy discharge technology for fast and precise projection welding. It provides stable weld quality, low heat impact, and is suitable for nuts, bolts, and metal components.
Capacitor Discharge (convex) Spot Welding Machine (DKR-6000)
Product Overview
The Capacitor Discharge (convex) Spot Welding Machine (Model DKR-6000) is a capacitor energy-storage resistance welding system designed for precise, reliable projection welding of nuts, bolts, and formed metal components, as well as conventional spot welding of conductive sheet metal parts.
Unlike conventional AC power-frequency and medium-frequency welding machines, this system stores electrical energy in capacitors and releases it rapidly during the welding cycle. The stored energy enables a high peak welding current (up to 60 kA short-circuit current) within a very short welding time — delivering strong, consistent welds with low heat input, excellent surface appearance, and reduced instantaneous power demand on the electrical grid.
The result is a combination of fast welding, low heat impact, clean surface quality, and high energy efficiency — an ideal solution for high-quality industrial production of nuts, bolts, stainless steel and carbon steel sheet metal assemblies.
Working Principle
The machine operates on a charge-and-discharge energy storage principle:
1. Energy Storage — The capacitors are rapidly charged and store electrical energy.
2. Energy Release — The stored energy is discharged instantly through the welding electrodes.
3. High-Current Welding — A high welding current is delivered to the workpiece within a very short period.
4. Strong Joint Formation — The concentrated energy generates the required welding heat at the contact area, forming a reliable spot or projection weld.
5. Rapid Cycle — After discharge, the system quickly recharges and prepares for the next welding cycle.
This operating principle allows high welding energy to be delivered without requiring a correspondingly high instantaneous power supply from the electrical grid — a key advantage for factories with limited power capacity.
Illustration: Close-up of a finished projection weld: the nut base is fused cleanly to the steel sheet with only light heat tinting and no discoloration of the surrounding surface.
Key Advantages
1. High Peak Welding Current. The capacitor energy storage system delivers a high welding current in a very short period, providing sufficient heat concentration for reliable spot and projection welding of nuts, bolts, projections, and other conductive metal components.
2. Short Welding Time. Rapid energy discharge significantly shortens the welding cycle, increasing production efficiency — especially suitable for automated and high-volume manufacturing.
3. Low Instantaneous Power Demand. Because energy is stored in the capacitors before welding, the machine does not require the same level of instantaneous mains power as conventional welding systems, reducing the required power capacity of the production facility.
4. Excellent Surface Appearance. The short-duration, concentrated welding process minimizes heat input to the surrounding material, significantly reducing surface blackening, discoloration, excessive indentation, thermal deformation, and post-welding surface damage.
5. Reduced or Eliminated Grinding. With optimized welding parameters, the weld appearance is clean with minimal discoloration — reducing or eliminating subsequent grinding and finishing operations.
6. Energy Efficient. Rapid charging and short-duration discharge improve energy utilization compared with conventional resistance welding, lowering operating costs.
7. Reliable Projection Welding. Controlled energy release achieves stable fusion at the projection point of nuts, bolts, and formed components while minimizing heating of the surrounding material.
Illustration: A stainless steel electrical cabinet panel with small, clean projection weld points around welded studs and nuts — minimal heat tint and no grinding required.
Capacitor Energy Storage Welding vs. Conventional AC / MF Welding
| Feature | Capacitor energy storage welding | Conventional AC / MF welding |
|---|---|---|
| Energy principle | Capacitor charge & rapid discharge | Direct power conversion |
| Peak welding current | High | Application dependent |
| Welding time | Very short | Relatively longer |
| Instantaneous power demand | Lower | Relatively higher |
| Heat input | Highly concentrated | Relatively higher |
| Surface discoloration | Significantly reduced | More likely |
| Workpiece deformation | Reduced | More likely under high heat input |
| Post-weld grinding | Often reduced or eliminated | May be required |
| Energy efficiency | High | Application dependent |
Typical Applications
Automotive. Welding nuts, bolts, brackets, reinforcement components, and other sheet metal assemblies.
New Energy & Energy Storage. Metal structural components, battery-related hardware, brackets, housings, and other conductive metal parts.
Aerospace & Defense. Precision joining applications where welding consistency, surface quality, and process reliability are important.
Hardware & Home Appliances. Metal hardware, appliance components, brackets, fasteners, and sheet metal assemblies.
Telecommunications. Metal cabinets, brackets, structural components, and other conductive hardware used in telecommunications equipment.
Electrical Equipment. Electrical enclosures, conductive components, terminals, brackets, and various metal assemblies.
Illustration: Projection-welded nuts on galvanized sheet metal cabinet panels and door hinge parts, ready for assembly on the production bench.
Suitable Materials and Application Range
The machine is designed for welding conductive metallic materials, including:
- Carbon steel and low-carbon steel
- Stainless steel
- Nuts and bolts
- Metal projections
- Other electrically conductive metal components
Mainly used for: nuts · bolts · stainless steel · carbon steel · sheet metal components · projection welds · spot welds. The machine is particularly well suited to applications requiring high welding current, short welding cycles, low heat input, and excellent surface quality. Actual welding capability depends on material type, thickness, joint design, electrode configuration, and required weld strength.
Frequently Asked Questions
Q1: What is the difference between capacitor discharge welding and conventional AC / medium-frequency welding?
A: Capacitor discharge welding stores energy in capacitors and releases it in a very short pulse, producing a high peak current with low instantaneous power demand and highly concentrated heat input. Conventional AC / MF welding draws power directly from the mains with longer welding time and higher heat input. The capacitor route gives cleaner surfaces, less deformation, and lower grid load; the AC / MF route suits applications needing sustained heat over longer weld times.
Q2: What parts is this machine best suited for?
A: It is optimized for projection welding of nuts, bolts, and other formed metal components, as well as spot welding of stainless steel and carbon steel sheet metal parts — common in automotive, new energy, appliance, telecom, and electrical equipment manufacturing.
Q3: Why does low instantaneous power demand matter?
A: Because the capacitors are charged gradually before welding, the machine does not pull a large instantaneous current from the grid at the moment of welding. Factories with limited power capacity can run the machine without upgrading their electrical infrastructure.
Q4: Can it reduce post-weld grinding?
A: Yes. The short, concentrated discharge minimizes surface blackening, discoloration, and indentation, so under suitable welding conditions the weld appearance is clean enough to reduce or eliminate grinding and finishing.
Q5: What is the delivery time and minimum order quantity?
A: The minimum order quantity is 1 unit. Standard packaging is a wooden case, and the typical delivery time is 14 working days.
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Contact PDKJ
Have nuts, bolts, or projection welding applications to discuss? Contact PDKJ with your workpiece details — we will recommend the right welding solution and configuration for your production.
WhatsApp: +86 136 1279 3248
Email: pdkj101@gd-pw.com
Website: Contact PDKJ Online
Address: 1-2F, Building 3, Qichen Industrial Park, No. 26 Luxi 1st Road, Liaobu Town, Dongguan City, Guangdong Province, China
