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Technical Tip: The Importance of Monitoring Torch Voltage in Atmospheric Plasma Spray


Torch voltage is a critical parameter in the atmospheric plasma spray process because it directly reflects the health and performance of the spray system. Voltage is influenced by the flow rates of process gases, the condition of the electrode and nozzle, and the plasma arc stability.


Equipment, Parts & Information for the Thermach Plasma Spray Thermal Spray Coating System

Monitoring torch voltage allows operators to detect wear or contamination in the electrodes and nozzle early, helping to prevent costly downtime and ensuring consistent coating quality. Deviations in voltage can also signal potential process instability, which could lead to inconsistent particle heating and deposition.





What Can Cause Torch Voltage to Change?


Several factors can impact torch voltage during operation, including:


  • Worn or Contaminated Electrodes and Nozzles: As these components wear, the arc path changes, increasing resistance and voltage.

  • Worn or Damaged Water-Cooled Cables: Aging or damaged cables can cause poor electrical conductivity, resulting in voltage fluctuations.

  • Improper Gas Flow Rates: Incorrect flow settings can destabilize the plasma arc, leading to inconsistent voltage.

  • Loose or Corroded Electrical Connections: Poor connections within the system can introduce resistance and lead to inaccurate voltage readings.

  • Contamination or Blockages in the Cooling System: Insufficient cooling can affect the electrode and nozzle temperature, altering the voltage.


Thermach thermal spray solutions: We can provide complete systems for thermal spray production.

Regular inspections and maintenance of these components are crucial to maintaining stable torch voltage and ensuring optimal process performance.


System Volts vs. Torch Volts:


It’s important to distinguish between system volts and torch volts, as they are not the same.


  • System Volts refer to the total voltage output of the power supply, including any resistance from cables, connections, and other components in the system.

  • Torch Volts specifically measure the voltage at the torch, where the plasma arc is generated. Torch voltage is a more accurate reflection of arc health and process conditions.


Misinterpreting these values can lead to incorrect troubleshooting or process adjustments. Always ensure you are monitoring torch voltage when evaluating the spray process.


Important Note:


Ensure the voltage leads are properly connected to your torch. This ensures the system can accurately read and display the torch voltage, providing reliable feedback for your process.  Below are the pink voltage sense leads attached to the positive and negative water cooled cables (left) and then at the arc starter (right).




 

Thermach continues to be on the leading edge of the thermal spray industry. We are launching next generation equipment and consumables throughout 2025.

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