Abrasive Water Jet Coating Removal with Sensor Feedback
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Solution Overview
Problem
Existing methods for removing coatings from substrates, such as turbine parts, are ineffective in controlling the removal of bond coats and often damage the underlying base metal, especially when dealing with irregular surface configurations and variations in coating thickness.
Innovation Solution
An abrasive water jet apparatus with a sensor system that maps the surface topography and adjusts the abrasive water jet's material removal rate to compensate for irregularities, using a detection device to ensure precise removal of the bond coat and diffusion layer without damaging the base metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a constant flow abrasive water jet is used to remove coatings, then the coating removal process is simple and continuous, but the method cannot compensate for variations in coating thickness and may remove excessive base metal
Solution Approach 1:
The abrasive water jet system transitions from constant flow to variable flow operation. The control system dynamically adjusts the jet flow rate based on real-time sensor feedback about coating thickness, enabling the system to remove material at optimal rates while preventing over-removal of base metal.
Solution Approach 2:
A sensor system continuously monitors the coating thickness and provides feedback signals to the control system. This closed-loop feedback mechanism allows the system to automatically adjust the abrasive water jet parameters to maintain precise control over material removal depth and rate.
2Reliability
If manual grinding or chemical stripping is used to remove coatings, then the process can be controlled to protect base metal, but the method is time-consuming and damages base metal through acid exposure
Solution Approach 1:
The system replaces manual mechanical grinding and chemical stripping processes with an automated abrasive water jet system. This substitution eliminates acid exposure to base metal while maintaining controlled material removal through automated flow rate adjustment and real-time thickness monitoring.
Solution Approach 2:
The abrasive water jet system dynamically changes operational parameters including flow rate, pressure, and abrasive particle characteristics based on real-time coating thickness measurements. This enables precise control over material removal while protecting the base metal from damage.
3Ease of operation
If the abrasive water jet removes equal amounts of coating during each pass, then the process is simple and consistent, but the method cannot handle irregular surface configurations and varying coating thickness
Solution Approach 1:
The sensor system performs preliminary measurement of the coating thickness and surface topography before the abrasive water jet begins removal. This advance information allows the control system to pre-plan the material removal strategy, adjusting jet parameters in advance to achieve uniform surfaces despite irregular initial conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus effectively removes coatings in a controlled manner, smoothing the surface and ensuring a pristine base metal for new coatings by varying the abrasive water jet's rate based on surface topography and detecting unique elements in the diffusion layer, thereby minimizing base metal removal.
Implementation Method 1
a sensor mounted generally adjacent the work holding system that senses the topography of the irregular exterior surface of the coating at a plurality of points and transmits electrical signals that are a function of the thickness of the coating
Implementation Method 2
a movable abrasive water jet that discharges a high pressure jet of water having an entrained abrasive material against and along the coating of the workpiece held by the work holding system to remove the coating therefrom
Implementation Method 3
discharges a high pressure jet of water having an entrained abrasive material against and along the coating
Data Source
AI summary
A method and apparatus for removing a coating having an irregular surface configuration that includes mapping the irregular surface configuration, and using the mapping determination in controlling the operation of an abrasive water jet to provide increased material removal rates at the higher points in the irregular surface and decreased material removal rates at the lower points, and thereby even out the surface configuration of the coating. The method and apparatus also includes using a detection device for detecting the presence or absence of an element that is unique to a layer of a coating, and using the detection determination in controlling the operation of the abrasive water jet to stop material removal of the coating when the detection device determines there is an absence of the unique element.