Practical Use of the Accuraspray Plume Sensor

Sauer Engineering www.SauerEngineering.com

John P. Sauer jopsauer@fuse.net

513-290-3617

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Accuraspray Usage in a Quick Summary

Accuraspray must be considered as a tool to gather data for either prototype work or process control

Accuraspray provides precise and absolute plume temperature, velocity etc.

Evolution over time of those parameters are recorded under the form of strip charts that can be compared to past trends.

Use requires gathering of initial data for comparison to future runs, developing a

database specific to your location and spray booths

In prototyping, Accuraspray can be used to o Map the varied process parameters used in developing the process

parameters o Reduce testing frequency when the Accuraspray is used to develop the

extremes of the parameters and can be used to fine tune the final settings o Allow for quick comparison of powder lots to determine best material for

future use o Develop plume, velocity, temperature profiles that can be used to transfer

settings to any booth or system o Allow for precise monitoring of plume angle/spray location, especially

critical for “location critical” spraying

In production, Accuraspray can be used to o Allow for precise monitoring of plume angle/spray location, especially

critical for “location critical” spraying o Quickly evaluate powder lot changes and change settings as required to

meet necessary “spray window” o Reduce troubleshooting by establishing a process baseline, eliminating

days if not weeks of multiple spray runs o With velocity or temperature can

See process shift from comparison to prior data Understand differences between powder lots Gun rebuild or maintenance issues Variation in primary/secondary gas flows

o With plume intensity and location can Observe nozzle wear Electrode wear Plume shift Variation in plume intensity indicating possible powder flow issues

Hopper issues Carrier gas flow issues Clogging

In purchase of new equipment and movement of equipment

o Use Accuraspray history for plume, velocity, temperature profiles as a starting point that can be used to transfer settings to any booth or system

o Will eliminate days of evaluation and lab testing

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General Use of the Accuraspray

Accuraspray must be thought of two separate systems o A camera which monitors the shape, location, angle, and intensity of the

plume-the location of monitoring can be set at any chosen length o Sensors which measure both temperature and velocity at a precise location

between the 2 red laser pointer locations

Two heads are available for the Accuraspray o High temp head for plasma which has filters to allow for measurement of

the high intensity-higher temperature plasma processes o Low temp head for HVOF like processes which has filters to allow for

measurement of the low intensity-lower temperature processes

Different filtersCamera

Temperature-Velocity Sensor

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Plume diagnostics with camera o Outputs will be

Plume width Plume height Plume location and angle

o What do I set Sampling line (regulates plume width) Plume angle (sets angle in picture perpendicular to real plume) Shutter speed (to keep plume shape on screen and not saturated) Gun position (try to center plume on the screen with location for

monitoring-this will be home position for monitoring and hopefully repeatable from measurement to measurement)

o Expectations Small movement in relative position on the screen is OK Change in shape-intensity is a sign of process shift

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Fundamentals: inside the sensor head, speed measurement

_________________________________________________________________________________

The Thermal Spray Sensor Company www.tecnar.com

Lens

Sensor Head

Optical Fibers

Detectors with Single Color Filters

Spray Direction

Time Shift

Typical Signals

Temperature: ratio of RMS values (twin wavelength pyrometry)

Velocity: time shift between signals (cross correlation)

Volume Measurement : 3mm diameter x 20-25mm DOF

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Velocity and temperature with sensors o Outputs will be

Temperature Velocity (critical that sensor is 90o to spray plume)

o What do I set Gun position (try to center plume on the screen with location for

monitoring-this will be home position for monitoring and hopefully repeatable from measurement to measurement)

Signal amplification Start at 128x and work down if needed Decrease saturation to acceptable level and increase

correlation

Measurement of response to changing signal amplification

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Output from Spray Runs

Strip chart available from all parameters such as temperature, velocity, intensity, plum width, etc.

o Can download to Excel and plot graphs

Screen shot as shown below. The computer is configured to snap the screen when you hit “print screen” and then the computer prompts you to save the bitmap to a specified location.

Video of the spray run which can be played up at optional speed settings and then a screen shot can be extracted from the video at a special spot if desired

Lower limit

Upper limit limit

Continuous value

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Accuraspray Set-up

You set up the Accuraspray perpendicular and parallel to the spray set-up and spray distance

The HVOF spray distance is approximately 10.5 inches between the two red set-up dots (Red Arrow)

The distance from the front of the sensor to the spray distance is always 8 inches-this is the “focal length” of the camera like focusing a 35 mm digital camera-it is always constant (Blue Arrow)

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Plasma Metco 450 Used Hardware

Significantgvariation

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Plasma Metco 450 New Hardware

Significantgreduction in variationwithwith new hardware

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Metco 204NS Used Hardware

Substantialvariation

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Metco 204NS New Hardware

Substantialreduction in variationwithwith new hardware

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Electrode Wear

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Nozzle Wear

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Metco 204 Comparison

Understand when hardware is worn out!!

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