What is Cad Welding?

Cad welding, also known as exothermic welding, is a specialized welding process used to create permanent electrical connections between two or more conductive materials, typically copper or other metals. This unique welding technique utilizes a controlled chemical reaction to generate intense heat, melting the metals and creating a molecular bond.

How Cad Welding Works

The cad welding process involves the following steps:

1. Preparation:

Prior to cad welding, the materials to be joined are cleaned and prepared. The surfaces are typically brushed or mechanically cleaned to remove any dirt, oxides, or contaminants, ensuring a clean and conductive connection.

2. Molds and Weld Metal:

Cad welding requires the use of a graphite or ceramic mold. The mold is designed to hold the conductive materials in place during the welding process. A weld metal, often in the form of a weld metal disk or powdered mixture, is placed inside the mold.

3. Ignition:

An ignition source, such as a flint igniter or electric igniter, is used to initiate the chemical reaction within the mold. The ignition triggers an exothermic reaction, causing the weld metal to melt and reach a molten state.

4. Welding Process:

As the weld metal melts, it flows and fills the space within the mold, enveloping the conductive materials. The high temperature and molten state of the metals allow them to mix and bond at a molecular level, creating a strong, reliable, and low-resistance electrical connection.

Advantages of Cad Welding

Cad welding offers several advantages, making it a preferred choice for certain applications:

1. Strong and Durable Connections:

Cad welding creates robust and long-lasting connections, capable of withstanding high electrical currents, mechanical stresses, and environmental conditions.

2. Low Electrical Resistance:

Due to the molecular bonding of the metals, cad welded connections offer low electrical resistance, ensuring efficient power transmission and minimal power loss.

3. Corrosion Resistance:

The cad welding process creates a metallurgical bond, resulting in corrosion-resistant connections that can withstand harsh environments and prevent degradation over time.

4. Versatility:

Cad welding can be used to join different metals, including copper, steel, aluminum, and bronze, allowing for versatile applications in various industries.

Applications of Cad Welding

Cad welding is commonly used in the following applications:

1. Electrical Grounding:

Due to its low resistance and high reliability, cad welding is extensively employed for grounding systems in electrical installations, ensuring effective dissipation of electrical faults and maintaining safe operating conditions.

2. Rail and Transportation:

Cad welding is utilized in the rail industry to create secure connections for rail bonds, track circuits, and signaling systems, ensuring efficient electrical continuity and reliable operation.

3. Telecommunications:

For telecommunications infrastructure, cad welding is employed to establish reliable connections for grounding, lightning protection, and bonding of copper or steel conductors.

4. Pipeline and Oil & Gas Industry:

In the pipeline and oil & gas industry, cad welding is used to join cathodic protection systems, ensuring corrosion prevention and extending the lifespan of pipelines and storage tanks.


Cad welding, or exothermic welding, is a specialized welding process that creates permanent, low-resistance electrical connections. With its strong bonding capabilities, durability, and corrosion resistance, cad welding is widely utilized in electrical grounding, rail systems, telecommunications, and the pipeline industry.

Proper safety precautions and adherence to guidelines are essential when performing cad welding to ensure reliable and secure connections.

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