Thermally Reversible Photocurable Patterns for Crack-Free Investment Casting
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Solution Overview
Problem
Existing investment casting methods face challenges in achieving highly accurate, high-strength, and easily removable three-dimensional investment patterns, with current technologies either lacking mechanical integrity or requiring high-temperature burning that leads to thermal expansion and shell cracking.
Innovation Solution
A thermally reversible, photocurable composition comprising monomers with varying glass transition temperatures, a thermally reversible crosslinker, and photoinitiator, which forms a strong pattern that softens and melts at controlled temperatures, ensuring mechanical strength and ease of removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If SLA and DLP resins are used to produce investment patterns, then superior accuracy and mechanical properties are achieved, but the patterns must be burned at temperatures greater than 200°C which leads to thermal expansion and shell cracking
Solution Approach 1:
The patent changes the thermal parameters of the investment pattern material by using a composition with glass transition temperature between 20-40°C and melting point between 40-60°C. This allows the pattern to be removed from the shell at low temperatures (200-250°C) without causing thermal expansion damage, while still maintaining the superior accuracy and mechanical properties of SLA/DLP resin-based patterns.
Solution Approach 2:
The patent creates a composite material system combining SLA/DLP resin components with specific additives and a controlled composition ratio. This composite formulation maintains the high accuracy and mechanical strength of traditional SLA/DLP patterns while modifying the thermal behavior to enable low-temperature removal without shell damage.
2Ease of operation
If FDM materials are used to create investment patterns, then easier pattern removal is achieved through melting at 100-200°C, but the patterns lack accuracy and have low mechanical properties
Solution Approach 1:
The patent modifies the thermal parameters of the pattern material to have a glass transition temperature of 20-40°C and melting point of 40-60°C. This enables the pattern to be removed by heating to 200-250°C where it softens and releases from the shell, achieving ease of removal like FDM materials while maintaining the superior accuracy and mechanical properties of SLA/DLP materials.
3Ease of operation
If high-temperature burning is used to remove investment patterns, then pattern removal is achieved, but thermal expansion causes shell cracking and integrity loss
Solution Approach 1:
The patent changes the thermal characteristics of the investment pattern material to have a melting point between 40-60°C and glass transition temperature between 20-40°C. This allows the pattern to be removed by heating to moderate temperatures (200-250°C) where the pattern softens and releases without causing thermal expansion that would crack the shell, thus maintaining shell integrity.
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
The composition maintains high mechanical strength below 130°C and softens above 130°C, allowing precise pattern removal without shell damage, enhancing the integrity and accuracy of investment casting processes.
Implementation Method 1
photocurable compositions that polymerize to a solid when exposed to UV light
Implementation Method 2
thermally reversible crosslinker having a UV curable functionality and a thermally reversible covalent bond
Implementation Method 3
an oligomer having two or more furan maleimide Diels-Alder adducts
Implementation Method 4
softens and melts upon heating
Implementation Method 5
monomer A having a glass transition temperature value less than about 25° C.; monomer B having a glass transition temperature value greater than about 25° C.
Data Source
AI summary
Thermally reversible, photocurable compositions is disclosed. The photocurable composition has high strength at low temperatures but also melts at elevated temperatures and is well suited as investment casting pattern composition.