Cast Component Pilot Hole Sealing for Core Position Repair
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Solution Overview
Problem
In investment casting, core positioning features often result in residual holes that can cause leakage and require additional processing to prepare for sealing plugs, which can be irregular and contaminated, making it difficult to achieve controlled wall thickness and reliable braze joints.
Innovation Solution
The process involves forming a core with integral bumpers or pins that create pilot holes during casting, which are then resized and filled with a sealing plug compatible with the alloy, ensuring proper sealing and internal feature formation through brazing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If core positioning features are used to position the core within the mold, then the core positioning and wall thickness maintenance are improved, but residual holes are created that cause leakage
Solution Approach 1:
The harmful residual holes created by core positioning features are extracted and removed through machining operations. The pilot holes are precisely located and removed to eliminate the leakage paths while preserving the beneficial core positioning function.
Solution Approach 2:
Sealing plugs are introduced as intermediary elements to fill and seal the residual holes created by core positioning features. These plugs act as mediators between the core positioning requirement and the leakage prevention requirement, allowing both functions to coexist.
2Reliability
If residual holes are sealed with sealing plugs, then leakage is prevented, but additional processing steps are required
Solution Approach 1:
The pilot holes are located and prepared in advance during the machining process before the sealing plug installation. This preliminary action of creating precisely positioned pilot holes simplifies the subsequent sealing operation and ensures proper alignment.
Solution Approach 2:
The core positioning features themselves serve to create the pilot holes that will later be sealed. The same features that cause the problem (residual holes) are utilized to define the location and geometry of the sealing sites, turning a harmful effect into a useful guide.
3Strength
If pilot holes are resized and sealed, then structural integrity is improved, but manufacturing time increases
Solution Approach 1:
The pilot holes are resized to optimal dimensions that accommodate the sealing plugs while minimizing material removal. The hole size, shape, and depth are carefully controlled to achieve the necessary structural integrity with minimal processing time.
Solution Approach 2:
The sealing plugs are made from materials compatible with the base alloy, creating a composite structure that restores structural integrity. The combination of the cast material, sealing plug material, and brazing material creates a unified structure with enhanced properties.
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 method provides controlled wall thickness and eliminates leakage issues by uniformly filling residual holes with a compatible sealing plug, enhancing the structural integrity and performance of cast components like heat exchangers and turbine airfoils.
Implementation Method 1
the installing of the sealing plug includes brazing the sealing plug to the cast component
Data Source
AI summary
An investment casting process for manufacturing a cast component is provided. The investment casting process includes forming a core, casting the cast component about the core such that a core positioning feature provides a location of an anticipated pilot hole in the cast component, removing the core from the cast component once the casting is completed, locating, forming and sizing a pilot hole to form a resized pilot hole that can receive a sealing plug and installing the sealing plug into the resized pilot hole.