Novel Blade System for Top-Down SLA 3D Printing

• Relevant Skills: SolidWorks, CAD, FDM 3D Printing, Mechanical Design, Finite Element Analysis (FEA), Experimental Design, Data Analysis

Situation

In the context of top-down stereolithography (SLA) 3D printing systems, maintaining consistent resin viscosity is a critical challenge. The viscosity of SLA resins can be affected by various factors, including exposure to UV light, dust, and debris. Over time, resins tend to settle at the bottom of the vat, and cured resin builds up, leading to unpredictable curing properties and reduced print resolution. Current solutions, such as discarding and replacing the resin, are costly and inefficient. This project aims to address these issues by developing a novel mechanical stirring system that maintains a uniform resin mixture throughout the printing process, thereby enhancing the quality and consistency of prints.

Task

The primary objectives of this project were to:

• Design and fabricate a mechanical stirring system for top-down SLA 3D printers.
• Ensure the system maintains a uniform resin mixture to prevent settling and contamination.
• Prolong the usability of the resin and minimize wastage.
• Improve print quality by maintaining consistent resin viscosity.
• Create a cost-effective and user-friendly solution that can be easily integrated into existing top-down SLA systems.
• Provide a comprehensive learning experience in additive manufacturing for the team members.

Action

Research and Problem Identification:

• Conducted a thorough literature review to understand the current challenges and existing solutions related to resin viscosity in SLA printing systems.
• Identified gaps in existing solutions and hypothesized that a mechanical stirrer could effectively address resin viscosity issues in top-down SLA systems.

Design Phase:

• Established design criteria focusing on cost-effectiveness, ease of use, and seamless integration into existing systems.
• Explored various stirring mechanisms, including ultrasonic, magnetic, and mechanical stirrers.
• Selected a mechanical approach due to its simplicity, reliability, and lower cost.
• Created detailed CAD models of the stirring system using SolidWorks, opting for an impeller blade design for efficient radial and axial flow mixing.

Simulation and Analysis:

• Conducted finite element analysis (FEA) to simulate the mechanical behavior of the stirrer under operational conditions.
• Refined the design based on simulation results to enhance durability, performance, and ease of integration.

Fabrication and Prototyping:

• Utilized FDM 3D printing technology to fabricate the stirrer components from PLA material, chosen for its durability and compatibility with uncured resin.
• Assembled the mechanical stirrer system, incorporating a motor, motor housing, and adjustable rail system for precise control of the blade height and speed.

Experimental Setup and Testing:

• Designed an experiment to test the effectiveness of the stirrer using a water and food coloring mixture to simulate resin behavior.
• Measured mixing efficiency by observing the time required for the food coloring to achieve a uniform mixture and return to a flat state.
• Conducted multiple trials to ensure data consistency and accuracy, with varying levels of "viscosity" represented by different amounts of food coloring.

Data Collection and Analysis:

• Collected and analyzed experimental data to evaluate the performance of the stirrer across different viscosity levels.
• Plotted graphs to illustrate the relationship between resin viscosity and mixing time, demonstrating the stirrer's effectiveness.
• Identified the need for further testing with actual resin and in real-world printing scenarios to fully validate the system’s performance.

Results and Discussion

The novel blade system effectively maintained a homogeneous resin mixture, reducing the time required for mixing and preventing settling. The impeller design was particularly effective in handling different viscosity levels, suggesting significant improvements in print quality and consistency for top-down SLA printers. The system is cost-effective and easy to use, meeting the initial design criteria. Potential improvements include incorporating filtration mechanisms to handle contaminants and optimizing the stirrer’s size for better spatial efficiency within the resin vat.

Conclusion and Recommendations

The project successfully developed a mechanical stirring system that demonstrated effective mixing capabilities in preliminary tests. The impeller blade design proved efficient in maintaining consistent resin viscosity, suggesting significant improvements in print quality and consistency for top-down SLA printers. Future work should focus on real-world testing, exploring ultrasonic mixers, and integrating filtration systems. This project provided valuable hands-on experience and enhanced the team’s understanding and skills in additive manufacturing.

Conclusion

The development of a mechanical stirring system for top-down SLA printers represents a significant advancement in additive manufacturing technology. By addressing resin viscosity challenges, the system offers potential applications in various industries requiring high-resolution and dimensionally accurate parts. This project not only provided a practical solution to a critical problem but also enhanced the team’s understanding and skills in additive manufacturing.