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What is Submersible SLA 3D Printing? A Comprehensive Analysis

20 June 2024

Comprehensive Analysis of Submersible SLA 3D Printing Technology

Submersible SLA industrial 3D Printing is a molding method that has been widely used in manufacturing due to its versatile material options and cost-effectiveness. In this article, let’s delve into what submersible SLA 3D printing entails, along with its requirements and process principles for product design.

Process Principle

Submersible SLA Industrial 3D Printing utilizes laser beams to solidify liquid resin. During the process, the platform descends layer by layer into the resin tank filled with liquid resin. A deflection mirror directs The laser onto the liquid surface, scanning according to the contour information. One plane scan produces a layer corresponding to the sectional contour, firmly bonded to the previously solidified part. This process repeats until the entire object is completed.

Process Overview

SLA stands for Stereolithography, a type of 3D printing technology that uses a process called photopolymerization to build parts. Similarly, Submersible SLA technology uses laser beams of specific wavelength and intensity to solidify liquid photosensitive resin but with the build platform submerged in the liquid resin tank. Moreover, the object being printed is formed beneath the surface of liquid resin.

For submersible SLA projects, in addition to printing, post-processing steps like cleaning, support removal, polishing, coloring, and curing are often required to meet the product requirements. Specifically, support structures are required for parts with overhanging structures, and these supports typically use the same material as the product.

Feature

High precision, smooth surface, and capability to produce large-sized products.
Good rigidity, sharp angles, and minimal shrinkage.
Smooth surface texture, detailed surface design, and high production efficiency.
Diverse resin types (white, translucent, transparent, high toughness) to meet various product requirements.

Applications

Suitable for rapid processing of high-precision, high-surface-quality, and detailed parts. For example, prototype samples in industries including automotive molds, medical biology, consumer electronics, gaming animation, architectural design, sculpture modeling, home decoration, etc.
Versatile resin options, help meet special requirements such as using heat-resistant resin for parts that undergo extreme heat environments.

Design Specifications

The design requirements for detailed structures in Submersible SLA Industrial 3D Printing are as follows:

Minimum wall thickness: 0.3mm(=0.012inch) (large thin sheets should be greater than 2mm(=0.079inch))
Minimum diameter for independent columns: 0.4mm(=0.0157inch)
Minimum convex (concave) stroke-width: 0.35mm(=0.0138inch)
Minimum hole diameter: 1mm(=0.039inch)
Minimum clearance: 0.5mm(0.019inch)

Design Principles

Shell reduction: “Shell” refers to the outmost structure that defines the shape of the printed object. “Shell reduction” refers to reducing the thickness of the outer shell or wall. For larger and heavier models, shell reduction is recommended as long as it does not affect their performance. This helps achieve lower cost and lighter weight, which potentially reduces production time as well. For large models, adding reinforcement ribs after reducing the shell thickness can significantly reduce the degree of deformation. The minimum shell thickness requirement in Submersible SLA is related to the overall size, with a minimum thickness of 2mm(0.079inch) recommended for small-sized parts (≤200mm or 7.87inch) and medium-sized parts (200-400mm or 7.87-15.7 inch), and over 3mm(0.12inch) for large-sized parts (≥400mm or 15.7inch).
35-degree design: Support structures are needed for overhanging parts, with the critical angle generally set at 35 degrees. Therefore, the angle between the overhanging part and the base should be greater than 35 degrees. Adding rounded corners can help avoid the need for support structures but maintain the size and quality control of the model.
0.35mm(=0.0138 inch) convex and concave detail: For concave text or surface details, it’s recommended to have a minimum line width and depth of 0.35mm, vice versa for protruding designs.
Part assembly: When designing parts that need to fit together, ensure proper tolerances and allowances for assembly. Printing certain parts separately whenever possible is advised to maintain optimal surface quality in the final product, with a clearance of at least 0.3mm(=0.012inch) generally recommended. However, for integrated models with movable parts that cannot be disassembled, a clearance of ≥0.4 mm(=0.0157inch) is recommended to avoid printing them as a single piece with other parts. In some cases, support beams (≥3mm or 0.118 inch)can be used to connect all the shells, ensuring no parts are lost during mass printing.

Process Principles

45-degree Orientation: The orientation of the model greatly affects both the surface quality and strength of the final product. It’s recommended to position the side with the most intricate features facing upwards. For curved parts. tilting them at a 45-degree angle or upright relative to the platform helps minimize visible stepping textures(like the contour maps), that may occur if placed horizontally. Furthermore, elongated workpieces are typically placed perpendicular to or at a 45-degree angle to the scraper.
Splicing for large parts: For parts that are larger than the available printing Volume, consider splicing the part and bonding it with AB glue. The splicing clearance should be greater than 0.3mm(=0.012inch). Triangular, rectangular, serrated, convex, and pin-type structures can be used for positioning the connection.
Holes and Channels: Design holes, channels, and/or other cavities on non-critical surfaces to ensure smooth outflow of liquid resin after shell reduction. The specific hole diameter is related to the size of the surface, but a minimum diameter of 3mm(=0.118inch) and a maximum diameter of 30mm(1.18 inch) are generally recommended. After post-processing, these process holes can be filled, fitted with grooves, and followed by polishing or other surface treatments.
Coloring part principle: For parts with simple coloring requirements, integrated printing followed by coloring is suitable. However, for parts with complex coloring needs, it’s recommended to print the coloring model based on colors separately and color each component separately. During the re-assembly, adhere to splicing principles to maintain connection structure, Additionally, consider post-processing techniques such as sanding or polishing to refine the appearance of the final assembled product, if necessary.

At InstaVoxel, we specialize in four primary 3D printing processes: SLA, SLS, SLM, and MJF. Each of these processes offers unique features and advantages, catering to diverse manufacturing needs. Contact us today to explore the seamless possibilities of 3D printing for your business needs!

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