Electron Beam Post-Curing for Thick 3D Printed Resin Parts
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Solution Overview
Problem
Existing post-curing techniques for additive manufacturing (AM) parts, such as UV curing and thermal curing, face challenges with thick sections, requiring extended cure times and potentially affecting dimensional stability.
Innovation Solution
The method involves 3D printing with photopolymerizable resins and post-curing the preformed parts using electron beams, which can penetrate thick sections without additional heating, allowing for efficient curing of sections up to 3.0 cm or more in thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal curing is used to post-cure thick sections (≥1.0 cm), then full cross-linking is achieved, but cure time is extended (≥1 hour) and dimensional stability is negatively affected
Solution Approach 1:
The patent replaces thermal curing (heat-based) with electron beam curing (radiation-based). The electron beam system uses high-energy electrons to directly initiate polymerization through radiolysis, eliminating the need for thermal activation and its associated long cure times and dimensional stability issues.
Solution Approach 2:
The patent changes the curing mechanism from thermal activation to radiation activation. By using electron beam radiation with energies typically in the range of 0.1-10 MeV, the system achieves rapid curing through direct energy deposition and free radical generation, reducing cure time from ≥1 hour to significantly shorter durations.
2Productivity
If UV curing is used for post-curing, then curing speed is improved, but light penetration is limited and thick sections cannot be fully cured
Solution Approach 1:
The patent replaces UV light-based curing with electron beam curing. Electron beams have much higher penetration capability than UV light, allowing full curing of thick sections (≥1.0 cm) that are inaccessible to UV methods. The electron beam energy can be adjusted to match the thickness of the workpiece.
Solution Approach 2:
The patent transitions from optical radiation (UV light with limited penetration depth) to particle radiation (electron beams with adjustable penetration depth based on energy). This dimensional change in the radiation type enables curing of thick sections that are beyond the reach of UV light.
3Reliability
If thermal curing additives are incorporated to enable thermal curing, then curing capability is improved, but material complexity and cost increase
Solution Approach 1:
The patent replaces thermal curing (which requires crosslinking additives) with electron beam curing. The electron beam directly generates free radicals through radiolysis of the monomer/oligomer, eliminating the need for thermal curing additives and simplifying material composition.
Solution Approach 2:
The patent extracts and removes the requirement for thermal curing additives from the material system. By using electron beam radiation, the curing process no longer depends on these additives, simplifying both material formulation and processing.
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 the time required for full curing, achieving full cross-linking in less than half the time of traditional methods, while maintaining dimensional stability and allowing for the post-curing of parts with complex geometries.
Implementation Method 1
subsequently post-curing the preformed part with electron beams
Implementation Method 2
The electron beam dosage of the electron beams to post-cure the preformed part is between 10 kilogray (kGy) and 100 kGy
Implementation Method 3
The UV curable resins polymerize via a free radical reaction when exposed to specific wavelength(s) of UV light
Data Source
AI summary
A method of forming a part includes 3D printing a photopolymerizable resin and forming a preformed part and subsequently post-curing the preformed part with electron beams. The preformed part may be cured via UV curing. A section of the preformed part post-cured with electron beams may have a thickness of at least 1.0 centimeter, for example, at least 2.0 centimeters or at least 3.0 centimeters. An electron beam dosage to post-cure the preformed part may be between 10 kilogray (kGy) and 100 kGy. The preformed part may be 3D printed using stereolithography (SLA), digital light processing (DLP) or material jetting (MJ) and the photopolymerizable resin may include at least one of an acrylate functional polymer and a methacrylate functional polymer. In the alternative, or in addition to, the photopolymerizable resin may include at least one of a urethane, a polyester, and a polyether.