Superplastic Forming Titanium Implant Enclosures
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Solution Overview
Problem
Conventional cold and hot stamping processes for titanium alloy medical device housings result in design compromises and require post-annealing procedures, leading to residual stress and microcracking, which limits design freedom and increases manufacturing costs.
Innovation Solution
Superplastic forming of titanium alloy metal sheets at elevated temperatures to achieve high elongations, allowing for the production of stress-free, complex housing parts with reduced design constraints, eliminating the need for subsequent annealing and enabling simultaneous formation of multiple implant device housings from a single sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If titanium alloy is cold formed into shapes suitable for compact implantable medical devices, then design freedom is improved, but excessive spring-back and cracking occur in areas of large deformation
Solution Approach 1:
The patent applies hot stamping instead of cold forming, changing the temperature parameter from room temperature to elevated temperature (typically 800-950°C for titanium alloys). This parameter change enables the material to achieve elongation of 10-15% at elevated temperature compared to only 10-15% elongation at room temperature, significantly reducing spring-back and cracking while maintaining design freedom for compact implantable medical devices
2Manufacturing precision
If hot stamping is employed to increase elongation percent, then manufacturing precision is improved, but design freedom is still limited and post vacuum annealing is required
Solution Approach 1:
The patent combines the forming and heat treatment operations into a single integrated hot stamping process. The titanium alloy is heated, formed, and cooled within the same die assembly, eliminating the need for separate post-vacuum annealing procedures. This merging of operations maintains the elongation benefits while reducing process complexity and eliminating additional post-processing steps
3Ease of manufacture
If conventional stamping processes are used, then manufacturing cost is reduced, but residual stress and reduced fatigue life result
Solution Approach 1:
The patent changes the temperature parameter from cold or conventional hot stamping to a specific elevated temperature range (800-950°C) that enables superplastic forming. This parameter change allows titanium alloys to achieve elongation exceeding 100%, dramatically reducing residual stress and improving fatigue life while maintaining manufacturing feasibility through a single-step process
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
Superplastic forming enhances design flexibility, reduces residual stress, and eliminates the need for post-processing annealing, resulting in more efficient and cost-effective production of titanium alloy medical device housings with improved fatigue life and charging efficiency for rechargeable devices.
Implementation Method 1
The heated titanium alloy metal sheet is forced onto the die and over each one of the plurality of housing forming areas, thereby superplastically forming a workpiece comprising a plurality of integrally formed implantable medical device housing portions
Data Source
AI summary
A titanium alloy metal sheet is provided and heated to a superplastic forming temperature. A die has a plurality of housing forming areas each corresponding to one of the medical device housing portions. The heated titanium alloy metal sheet is forced onto the die and over each one of the plurality of housing forming areas, thereby superplastically forming a workpiece comprising a plurality of integrally formed implantable medical device housing portions.