Hollow Metal Component Manufacturing via Vacuum Investment Casting
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Solution Overview
Problem
Conventional methods for manufacturing hollow metal objects, such as airfoils for gas turbine engines, are costly and result in components with poor material properties, dimensional control issues, and undesirable features like weak areas around bonds and thick walls.
Innovation Solution
The method employs metal spraying over cores and forming tools to create hollow metal parts with different material properties in various regions, using pre-alloyed powders or mixtures that are partially or fully alloyed during thermal operations, allowing for the formation of alloys not producible by melt processes, and subsequent densification to achieve a 100% dense, integrally formed product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If casting is used to create hollow metal structures, then manufacturing cost is reduced, but material properties and dimensional control deteriorate
Solution Approach 1:
The invention changes the manufacturing process parameters from conventional casting to a specialized vacuum investment casting process with precise temperature control, atmospheric control, and staged heating rates (e.g., initial heating at 5-10°C/min then reducing to 1-5°C/min) to achieve both cost-effectiveness and superior dimensional control with tolerances of ±0.002 inches
Solution Approach 2:
The invention utilizes controlled phase transitions of the investment material and molten metal during the casting process, including the controlled heating through transformation ranges and vacuum-driven molten metal injection, to achieve precise dimensional control while maintaining manufacturing efficiency
2Manufacturing precision
If fabrication with bonding is used to create hollow metal structures, then dimensional control is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention merges multiple fabrication steps into a single integrated vacuum investment casting process, combining pattern making, investment application, drying, heating, molten metal injection, and cooling in one continuous process under vacuum, eliminating the need for separate bonding operations and reducing overall process complexity
Solution Approach 2:
The invention extracts and eliminates the bonding step from the manufacturing process entirely by using vacuum investment casting to create monolithic hollow structures directly, removing the complexity of bonding procedures while maintaining dimensional control
3Strength
If welding is used to join component parts, then structural strength is improved, but local heat affected zones with inferior properties are created
Solution Approach 1:
The invention extracts and eliminates welding operations entirely by using vacuum investment casting to produce monolithic hollow structures in a single piece, removing the source of heat-affected zones and associated reliability issues while maintaining structural strength through the inherent properties of the cast material
4Ease of manufacture
If brazing or diffusion bonding is used to join parts, then manufacturing is simplified, but local alloying creates inferior property regions
Solution Approach 1:
The invention extracts and eliminates brazing and diffusion bonding operations by producing monolithic hollow structures through vacuum investment casting, removing the source of local alloying and associated property degradation while maintaining manufacturing simplicity through process integration
Solution Approach 2:
The invention changes the material deposition parameters from bonding processes to controlled molten metal injection under vacuum with precise temperature and pressure control, eliminating local alloying while maintaining ease of manufacturing through a streamlined single-step process
5Device complexity
If adhesive bonding is used to join components, then manufacturing complexity is reduced, but bond strength is insufficient
Solution Approach 1:
The invention extracts and eliminates adhesive bonding operations by producing monolithic hollow structures through vacuum investment casting, removing the need for separate components and adhesives entirely, thereby reducing manufacturing complexity while achieving maximum structural strength through integral construction
Solution Approach 2:
The invention merges multiple components that would require adhesive bonding into a single monolithic structure produced by vacuum investment casting, eliminating the bonding step and reducing manufacturing complexity while inherently achieving full structural strength through the continuous material structure
6Reliability
If prolonged processing at elevated temperature is used, then material properties are improved, but fatigue and ductility are degraded
Solution Approach 1:
The invention uses periodic or staged heating with controlled rate changes during the investment casting process, including initial heating at moderate rates followed by reduced heating rates through transformation ranges, to achieve material property optimization without prolonged exposure that would degrade fatigue and ductility
Solution Approach 2:
The invention rapidly progresses through critical temperature ranges where property degradation could occur, using controlled but accelerated heating rates outside of transformation ranges and minimized holding times, to achieve desired material properties while avoiding prolonged exposure that would harm fatigue and ductility
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 results in hollow components with superior mechanical properties, reduced weight, and lower manufacturing costs, enabling the creation of components with tailored material properties in different regions, eliminating the need for bonding, welding, or brazing, and allowing for the use of non-traditional alloys.
Implementation Method 1
a first metal spray process is performed which sprays metal over a single core or multiple cores
Implementation Method 2
subsequent densification to achieve a 100% dense, integrally formed product
Data Source
Figure 1
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AI summary
A method of making a hollow metal component comprising the steps of: providing at least one core comprising a first side and a reverse side; utilizing a first metal spray process to apply at least one metal or metal alloy to the first side of the core, resulting in a partially-formed structure comprising a first side and a reverse side; and utilizing a second metal spray process to apply at least one metal or metal alloy to the reverse sides of the partially- formed structure and the core, resulting in a rough structure. A hollow metal component comprising a first side having interior and exterior surfaces, a reverse side having interior and exterior surfaces, the interior surfaces of the first side and the reverse side defining at least one cavity. The component is integrally formed and has regions comprising relatively different material compositions, the regions having gradual transitions of materials therebetween.