Abrasive Flow Machining High-Aspect Passages
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Solution Overview
Problem
Components with internal cavities formed by casting or additive manufacturing often have high surface roughness, which can affect mechanical properties and coolant flow in gas turbine engines, and existing abrasive flow machining techniques are limited in polishing high-aspect passages effectively.
Innovation Solution
The method involves using a low-viscosity abrasive media with a high aspect ratio passage geometry, such as waveform, helical, or swirl vane designs, to preferentially polish target surfaces by controlling the flow and pressure of the abrasive media, ensuring efficient abrasion and surface smoothing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional abrasive flow machining is used on high-aspect passages, then the passage surfaces can be polished, but the abrasive media cannot effectively reach and polish all target surfaces due to flow distribution issues
Solution Approach 1:
The passage geometry is specifically designed with varying cross-sectional areas, constrictions, and expansions at different locations to create localized flow characteristics. This ensures that abrasive media flow is optimized for each specific region of the passage, enabling effective polishing of target surfaces that would otherwise be inaccessible or poorly reached by uniform flow methods
Solution Approach 2:
The passage geometry includes dynamic features such as constrictions and expansions that actively manipulate the abrasive media flow as it moves through the passage. These geometric variations create changing flow conditions that adapt to different passage sections, ensuring continuous contact between abrasive particles and target surfaces throughout the high-aspect passage
2Manufacturing precision
If abrasive media flows through high-aspect passages, then polishing can occur, but the abrasive media pressure is insufficient at target surfaces to achieve effective abrasion
Solution Approach 1:
The passage geometry is pre-designed with constrictions upstream of target abrasion zones that accelerate the abrasive media flow before it reaches the polishing surfaces. This preliminary acceleration ensures that abrasive particles arrive at target surfaces with sufficient kinetic energy and local pressure to achieve effective abrasion and desired surface roughness reduction
Solution Approach 2:
The passage geometry strategically varies cross-sectional area, creating constrictions and expansions that modify local flow parameters including velocity and pressure. These parameter changes ensure that abrasive media maintains adequate pressure and flow velocity at target surfaces throughout the high-aspect passage, enabling consistent polishing performance
3Manufacturing precision
If the abrasive media viscosity is high, then the abrasive particles can effectively abrade surfaces, but the media cannot flow through high-aspect passages efficiently
Solution Approach 1:
The abrasive media formulation is specifically adjusted to achieve optimal viscosity parameters that balance flowability through high-aspect passages with effective abrasion capability. The media composition and rheological properties are tuned to ensure sufficient flow rate while maintaining adequate abrasive particle energy for effective surface polishing
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
This approach effectively reduces surface roughness to less than 30 microinches (0.76 micrometers) in high-aspect passages, improving mechanical properties and coolant flow, and is particularly suitable for complex geometries that other methods cannot readily polish.
Implementation Method 1
The paste includes a high volume of abrasive particles that abrade the cavity surfaces and thus reduce roughness
Implementation Method 2
passage geometry that is configured to direct flow of the abrasive media into the target abrasion surfaces such that the target abrasion surfaces are preferentially polished
Data Source
AI summary
A method for abrasive flow machining includes moving an abrasive media through a high-aspect passage of a workpiece. Local pressure of the abrasive media is increased at target abrasion surfaces of the high-aspect passage using a passage geometry that is configured to direct flow of the abrasive media into the target abrasion surfaces such that the target abrasion surfaces are preferentially polished by the abrasive media over other, non-targeted surfaces of the high-aspect passage at which the flow of the abrasive media is not directed into.