How does the SG-100 Plasma Spray Torch Work?

First, key components (see diagram picture above):

1. Powder Port: External injection (radial injection) into the plasma jet.

2. & 3. Power & Water Connections: Combine electrical power delivery with cooling water flow — a common design in plasma torches to reduce the number of hoses.

4. Arc Gas: Primary plasma-forming gas.

5. Cathode: Usually a tungsten electrode (sometimes with hafnium or zirconium for air plasma). This is the negative electrode where electrons are emitted.

6. Anode: Copper nozzle with precise internal geometry. The arc attaches here. It’s the part that experiences the most wear.

Second, how does it work?

Gas Introduction

• Arc Gas (4) enters near the rear. This is usually argon, nitrogen, helium, or a mixture. It flows between the cathode (5) and the anode (6).

• Powder + Carrier Gas (1) is injected downstream (usually into the hot plasma jet after the arc zone). The carrier gas (often argon) transports the spray powder into the flame.

Arc Initiation & Plasma Generation

• High-voltage DC power is applied:

  • Positive (+) connection (2) goes to the anode (6).

  • Negative (-) connection (3) goes to the cathode (5).

• A high-voltage spark or pilot arc first ionizes the arc gas, creating a conductive path.

• Once established, a powerful electric arc jumps from the tip of the cathode to the inside wall of the anode (nozzle). This arc is extremely intense and heats the gas to plasma state — a superheated, ionized gas that conducts electricity and carries enormous thermal energy.

Cooling System

• The torch runs very hot, so it has an internal water cooling circuit:

  • Water inlet (3) brings cool water in.

  • Water outlet (2) removes heated water.

• The water flows through channels around the anode and cathode to prevent them from melting.

Plasma Jet Formation

• The hot plasma is forced through the narrow anode nozzle, accelerating it to high velocity (often Mach 1–2+).

• This creates a long, bright plasma flame exiting the front of the torch.

Powder Injection & Coating Process

• Powder particles are injected into the plasma jet (via port 1).

• The plasma instantly melts the particles (or at least softens them significantly) and accelerates them to hundreds of meters per second.

• These molten or semi-molten droplets impact the workpiece at high speed, flatten (splat), and rapidly solidify, building up a coating layer by layer.

Learn more and order the SG-100 Plasma Torch from Thermach here.

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Remember, Thermach is not your competitor; your other options are. We don’t coat; we only supply thermal spray equipment and parts. You can proceed with confidence, knowing that our team is dedicated to creating a custom system that meets your exact specifications.

Manufacturer of Equipment & Parts for the Thermal Spray Industry. Backed by Reliable, Timely Service & Support.

Thermach manufactures thermal spray coating systems for the coating industry. We don't coat. We provide the equipment and parts necessary for you to run a successful coating operation. Our mission is to ensure your coating process is running smoothly with Thermach equipment.