Rotating Mandrel for Uniform Silicone Implant Shells
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Solution Overview
Problem
Existing methods for molding soft prosthetic implant shells, such as dip-molding and spray-molding, often result in non-uniform shell thickness due to gravitational flow issues, leading to inefficiencies and the need for multiple immersions to achieve desired thickness.
Innovation Solution
The method involves spinning and rotating mandrels during the devolatilization step to ensure an even covering of silicone dispersion, utilizing centrifugal forces to maintain the material on the mandrel surface and prevent runoff, thereby achieving uniform shell thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dip-molding or spray-molding is used to form implant shells, then the shell can be manufactured with flexible silicone elastomer, but the shell thickness becomes non-uniform due to gravitational flow
Solution Approach 1:
The mandrel is rotated during the dip-molding process to dynamically change the orientation of the shell surface relative to gravity. This rotation prevents the silicone dispersion from flowing preferentially in one direction, ensuring uniform material distribution and consistent shell thickness throughout the implant.
2Manufacturing precision
If multiple immersions are performed to achieve desired shell thickness, then the shell thickness can be increased, but the manufacturing time and process complexity increase
Solution Approach 1:
By rotating the mandrel continuously during the dipping process, the invention achieves uniform material distribution in a single immersion, eliminating the need for multiple sequential immersions and significantly improving manufacturing efficiency.
Solution Approach 2:
The continuous rotation of the mandrel during dipping ensures that all surfaces of the shell receive equal exposure to the silicone dispersion, allowing the desired thickness to be achieved in one continuous action rather than through multiple discrete steps.
3Device complexity
If the mandrel is stationary during dipping, then the process is simple, but material runs off the mandrel due to gravity causing non-uniform thickness
Solution Approach 1:
Rotating the mandrel during dipping creates a dynamic system where centrifugal forces counteract gravitational flow, preventing material runoff and ensuring uniform coating without requiring complex additional equipment.
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 significantly reduces material waste and ensures consistent shell thickness across the implant, improving manufacturing efficiency and reducing the number of required dipping or spraying steps.
Implementation Method 1
spinning and rotating mandrels during the devolatilization step to ensure an even covering of silicone dispersion, utilizing centrifugal forces to maintain the material on the mandrel surface
Implementation Method 2
spinning and rotating mandrels during the devolatilization step to ensure an even covering of silicone dispersion, utilizing centrifugal forces to maintain the material on the mandrel surface and prevent runoff
Implementation Method 3
The mandrel is withdrawn from the dispersion and the excess dispersion is allowed to drain from the mandrel. After the excess dispersion has drained from the mandrel at least a portion of the solvent (typically xylene) is allowed to evaporate to stabilize the silicone elastomer coating, forming a gum state.
Data Source
AI summary
Systems and methods for molding shells for fluid-filled prosthetic implants, including spinning and rotating dip- or spray-mandrels during a devolatilization step to ensure an even covering. The mandrels may be spun during the dipping or spraying step, and/or afterward while a solvent evaporates until a gum state is formed. The techniques are particularly useful for forming hollow shells from silicone dispersions for soft implants, such as breast implants.