Initial Research Pathway

Initial research pathways:

• Used gAI, ChatGPT to research on the different technologies of resin 3D printing. Gave ChatGPT the prompt "What are the main technologies used in resin 3D printing?". The 3 main technology presented are as follows

• Stereolithography (SLA)

• Digital Light Processing (DLP)

• Masked Stereolithography (mSLA)

Gave ChatGPT the prompt "Explain Stereolithography", as me and my partner Zhi Xian have decided to focus on the Stereolithography technology. The following information are taken from ChatGPT.

Stereolithography (SLA) is a 3D printing technology that uses a process called photopolymerization to create objects layer by layer. It's one of the earliest forms of 3D printing, developed in the 1980s by Charles Hull, and is known for producing high-precision models with smooth surface finishes. Here's how it works and why it's popular:

How Stereolithography Works:

1. 3D Model Preparation: The process starts with a 3D design created using CAD software. The model is then "sliced" into layers, which define the shape of each horizontal cross-section of the object.

2. Resin Vat: The core of the SLA printer is a vat filled with liquid photopolymer resin. This resin is sensitive to ultraviolet (UV) light and will solidify when exposed to it.

3. Laser Curing: A UV laser is directed at the surface of the liquid resin. Following the pattern dictated by the CAD model's cross-sectional layer, the laser traces out the shape of each layer. As the laser hits the resin, it cures (solidifies) the material in the desired shape.

4. Layer-by-Layer Building: After a layer is cured, the build platform lowers slightly (usually by a fraction of a millimeter), exposing a fresh layer of liquid resin. The laser continues to trace and solidify each successive layer, building the object from the bottom up.

5. Post-Processing: Once the object is fully printed, it is often rinsed in a solvent to remove any excess uncured resin. In some cases, a post-curing process with additional UV light is used to further harden the object and improve its mechanical properties.

Key Features of SLA:

• High Precision and Accuracy: SLA can produce parts with fine details and smooth surfaces, with resolutions often reaching down to 25 microns (0.025 mm).

• Smooth Surface Finish: Since the layers are thin and the process uses a liquid material, SLA objects have smoother surfaces than those made by Fused Deposition Modeling (FDM), which uses filament.

• Material: SLA printers use photopolymer resins, which are available in different varieties, including flexible, tough, biocompatible, and heat-resistant versions. The material properties can be tailored to specific applications, making SLA versatile.

Applications:

• Prototyping: The high precision makes SLA ideal for creating functional prototypes, especially when aesthetic or fit testing is important.
• Dental and Medical Models: SLA is widely used to create dental models, surgical guides, and hearing aids, due to its biocompatible materials and detail accuracy.
• Jewelry Casting: Jewelers use SLA printers to produce highly detailed wax models for investment casting.
• Engineering: Engineers use SLA to create accurate prototypes and test parts for fit and functionality before going into full production.

Advantages of SLA:

• Fine Detail and Complex Geometries: It can create highly intricate and detailed parts that other 3D printing technologies struggle with.
• Variety of Materials: There is a wide range of resins with specific properties tailored to different industrial needs.
• Smooth Surfaces: The objects produced have a superior surface finish, often requiring little to no post-processing.

Disadvantages of SLA:

• Cost: SLA printers and resin materials tend to be more expensive compared to FDM and other technologies.
• Post-Processing: Although the surface finish is smoother, SLA parts often require cleaning and additional curing steps after printing.
• Material Limitations: While SLA resins offer a variety of properties, they generally aren't as durable as some thermoplastics used in other types of 3D printing.

In summary, Stereolithography is highly valued for its ability to produce detailed and smooth parts, making it ideal for industries requiring precision and aesthetic quality. However, the cost and post-processing requirements can be higher than those of other 3D printing methods.

 -  Some applications of resin 3D printing:

- Prototyping (/Rapid)

- Manufacturing

- Dental and Medical parts/equipment

- Jewelry

- Education and Research

- Entertainment and Art

150-200 words: description, feature, function, thesis (opinion on the tech), minimum 3 articles

How basic stereolithography (SLA) works:

(Temporary sources:)

SLA - one of the earliest and most widely used forms of additive manufacturing. It works by using a laser to cure and solidify layers of a photopolymer resin.

https://www.mdpi.com/2227-9717/8/9/1138 - A Review of Stereolithography: Processes and Systems

https://www.mdpi.com/2076-3417/12/7/3591 - Photopolymerization of Ceramic Resins by Stereolithography Process: A Review

1. 3D model created using CAD, sliced into multiple thin layers

2. Printer uses a UV laser to trace a layer of model onto the surface of liquid resin, resin solidifies (Cures) where the laser hits.

3. Build platform lowers slightly, and next layer is traced and cured. This repeats until the entire object is formed.

4. Object is then removed from resin and typically undergoes additional curing in a UV oven to ensure full polymerisation and strength

MSLA - variation of SLA that uses a digital light projector to cure the resin. Instead of a laser, MSLA uses an LCD screen to project an image of each layer onto the resin surface.

https://www.mdpi.com/2227-9717/8/9/1138 - A Review of Stereolithography: Processes and Systems

https://viterbi-web.usc.edu/~yongchen/Papers/2014_Before/Digital_Material_RPJ_Printed.pdf - Digital material fabrication using mask-image-projection-based stereolithography

1. Preparation: Similar to SLA, a 3D model is sliced into layers.

2. Layer Projection: An LCD screen displays the entire layer pattern at once, and a UV light source cures the resin through the mask created by the LCD.

3. Layer Curing: The build platform lowers, and the next layer is projected and cured. This process continues layer by layer.

4. Post-Processing: The object is removed and further cured if necessary.

MSLA can be faster than traditional SLA because it cures an entire layer at once rather than tracing it with a laser

LFS - an advanced form of SLA designed to reduce the forces exerted on the part during the printing process. This is achieved through a flexible tank and a linear illumination system.

https://www.mdpi.com/2227-9717/8/9/1138 - A Review of Stereolithography: Processes and Systems

https://pure.hw.ac.uk/ws/portalfiles/portal/10766137/Melchels2010_Biomaterials_31_24_6121.pdf - A review on stereolithography and its applications in biomedical engineering

1. Preparation: The 3D model is sliced into layers.

2. Layer-by-Layer Printing: A linear illumination system cures the resin layer by layer. The flexible tank allows for gentle peeling of each layer, reducing the stress on the part.

3. Layer Curing: The build platform lowers, and the next layer is cured. The flexible tank minimizes the forces during this step.

4. Post-Processing: The printed object is removed and typically undergoes additional curing.

References

https://3dpros.com/printers/formlabs-form-3l

https://formlabs.com/3d-printers/form-3l/?ppinv=1

https://www.matterhackers.com/store/l/formlabs-form-3l-sla-3d-printer

https://www.additive-x.com/blog/your-guide-to-the-formlabs-form-3l/

https://formlabs.com/blog/new-improvements-form-3l/

https://www.mdpi.com/2227-9717/8/9/1138

https://link.springer.com/referenceworkentry/10.1007/978-90-481-9751-4_377

https://scholar.google.com/

https://link.springer.com/article/10.1007/s12206-023-1113-2

https://doi.org/10.3390/pr8091138

Edited 3/10/24