GST SVision Thermal Spray Diagnostics System

How GST SVision Works

GST SVision uses a high-speed optical measurement system to observe particles moving through a defined measurement area within the thermal spray plume. Image-processing and signal-analysis algorithms evaluate particle motion and radiation to calculate key process parameters.

Depending on the configured measurement package, the system can monitor particle velocity, particle temperature, spray-plume position, plume width, spray direction and divergence. Particle-size analysis can also be incorporated where supported by the selected process and optical configuration.

The measurement area can be adapted to the width and geometry of the spray plume, allowing the same diagnostic platform to be used with different spray processes, guns and operating conditions. This is particularly useful in facilities operating several thermal spray technologies from a common process-development laboratory.

Key benefits

• Direct measurement of the thermal spray process rather than relying only on equipment setpoints.
• Real-time monitoring of in-flight particle velocity and temperature.
• Analysis of spray-plume position, width, angle and divergence.
• Support for HVOF, plasma spray, HVAF, flame spray and arc spray process development.
• Helps establish repeatable correlations between spray parameters and coating properties.
• Enables faster identification of process drift caused by nozzle wear, powder variations or changes in gas conditions.
• Supports development and validation of qualified thermal spray recipes.
• Suitable for both R&D and routine production quality control.
• Adjustable optical measurement area for different spray-plume sizes.
• Digital process data can be stored and compared between batches, shifts or coating programs.
• Compact sensor architecture supports installation near existing thermal spray equipment.
• Can be incorporated into automated coating cells and centralized process-monitoring systems.

Thermal Spray Process Monitoring

Stable coating quality depends on more than maintaining the programmed machine settings. Changes in spray-gun condition, powder morphology, injector geometry, gas supply or process environment can alter particle behavior even when the nominal recipe remains unchanged.

GST SVision provides an additional process-control layer by measuring the result of these variables directly in the spray plume. Changes in average particle velocity may indicate variations in gas dynamics, combustion conditions or nozzle condition. Changes in particle temperature can indicate differences in thermal input, powder injection or residence time. Monitoring plume position and geometry can reveal gun alignment problems, injector changes or instability in the spray process.

This information allows process engineers to identify deviations before they result in unacceptable coating quality.

Particle Velocity Measurement

Particle velocity is one of the most important parameters in HVOF and other kinetic-energy-dominated thermal spray processes. GST SVision tracks particle movement through the optical measurement area and calculates the in-flight velocity of the spray particles. Velocity data can be used to compare spray parameters, optimize deposition conditions and detect changes in gun performance. Consistent particle velocity contributes to repeatable particle deformation, coating density and bonding behavior.

Particle Temperature Measurement

Particle temperature provides information about the thermal state of the feedstock before impact with the substrate. Monitoring temperature is particularly important in plasma spray and flame spray processes, where insufficient heating can reduce particle deformation while excessive thermal exposure may increase oxidation or alter feedstock chemistry. Combined analysis of particle temperature and velocity provides a significantly more complete picture of the spray process than either parameter alone.

Spray Plume Analysis

GST SVision can be used to analyze the macroscopic geometry and stability of the spray plume. Depending on the configured system, process parameters may include:

• Plume center position.
• Spray width.
• Spray angle.
• Plume divergence.
• Relative particle flux.
• Particle distribution across the plume.

Monitoring these parameters makes it possible to detect changes in injector alignment, gun hardware condition or process stability.

Process Development

During coating development, GST SVision allows engineers to compare different process windows without relying exclusively on destructive coating tests. Process-development work can include evaluating:

• Gas-flow combinations.
• Powder feed rate.
• Carrier-gas settings.
• Spray distance.
• Gun hardware.
• Powder particle-size distribution.
• Injector configuration.
• Combustion parameters.

Measured particle data can then be correlated with coating properties such as porosity, hardness, deposition efficiency, oxide content and bond strength. This can reduce the number of trial-and-error coating runs required during process development.

Production Quality Control

Once a thermal spray process has been qualified, GST SVision can be used to establish a reference process window.

Production measurements can then be compared against the validated reference values. Deviations in particle temperature, velocity or plume geometry may indicate that the spray process is moving outside the qualified operating range.

This makes the system useful for incoming equipment qualification, scheduled process verification, preventive maintenance and production quality assurance.

Technical Parameters - Benchmark Configuration

The following values are based on the published SprayWatch 2S benchmark used as the functional reference for GST SVision. They must be confirmed for the final GST SVision hardware and software configuration before publication.

Integration with GST Thermal Spray Systems

GST SVision can be incorporated into complete GST thermal spray production cells and process-development installations. The diagnostic system can operate together with:

• GST plasma spray systems.
• GST HVOF systems.
• Flame spray equipment.
• Industrial robots and gun manipulators.
• Workpiece positioners.
• Process-control systems.
• Spray booths and extraction equipment.

For automated production lines, measured process data can also be used as part of a broader quality-monitoring architecture, allowing production records to be associated with specific coating programs, components or batches.

Why Measure the Spray Instead of Only the Machine?

Two identical machine recipes do not necessarily guarantee identical particle conditions.

Nozzle wear, powder properties, injector condition, gas supply and environmental factors can change the spray plume without producing an obvious change in the programmed equipment parameters.

GST SVision provides visibility into what is actually happening between the spray gun and the component.

This gives operators and process engineers an additional tool for:

• Process validation.
• Troubleshooting.
• Preventive maintenance.
• Coating development.
• Production quality assurance.
• Comparison of spray guns and consumables.

Applications