Session: 06-11-01: Biotechnology and General Applications

Paper Number: 142533

142533 - Impact of Uv Curing on Process Variability for Impact-Resistant Sla 3d Printed Parts 

Background: Stereolithography (SLA) 3D printing offers high resolution and customization, making it suitable for personalized medical devices like prosthetic limbs and bone scaffolds. However, its application in weight-bearing components is limited due to inconsistent mechanical properties, particularly impact resistance. This inconsistency can lead to product failure and compromise user safety, hindering wider adoption of SLA for these demanding applications. This study investigates the influence of UV curing parameters (time and temperature) on the process variability of impact resistance in SLA-printed parts, aiming to contribute to the advancement of SLA technology for reliable and high-performance weight-bearing components.

 

Methods: Inspired by a 3x3 factorial design, the experiment explored five combinations of curing temperature (45°C, 60°C, 75°C) and time (15 min, 30 min, 45 min), with 13 specimens printed and tested for each combination (total of 65 specimens). Notably, the manufacturer's recommended setting (60°C for 30 minutes) was included as a control, while the other combinations aimed to understand the impact of deviating from this recommendation. To quantify process variability, the process capability index (Cpk) was calculated for each combination. Correlations between Cpk and curing parameters were assessed using Spearman's rank correlation coefficient due to the non-normal distribution of the data, as confirmed by the Kolmogorov-Smirnov test.

 

Results: Cpk values ranged from 0.04 to 0.63, indicating significant variability across curing conditions. While increasing curing time showed a positive trend with Cpk (higher Cpk implying better consistency), the correlation wasn't statistically significant (rs = 0.62, p > 0.05). Conversely, a negative trend was observed between Cpk and curing temperature, but again, not statistically significant (rs = -0.32, p > 0.05).

 

Interpretation: Although statistically significant correlations weren't established, the observed trends suggest potential effects of UV curing parameters on process variability. Increasing curing time might lead to improved consistency, possibly due to more complete photopolymerization, allowing for better crosslinking within the resin and potentially reducing the number of partially cured areas. Conversely, higher curing temperatures might have the opposite effect, potentially due to uneven curing within the chamber caused by temperature gradients or excessive thermal stress, which could introduce microcracks or other defects in the printed parts. This interpretation is supported by the observed substantial variation in Cpk across different conditions, hinting at potential non-uniformities within the curing chamber. However, further investigation of the curing chamber is needed to confirm these potential non-uniformities.

Presenting Author: Anne Schmitz UW Stout

Presenting Author Biography: I received my Mechanical Engineering undergraduate degree from the University of Wisconsin-Madison. During my schooling, I explored many opportunities to apply my engineering degree. I was involved with the Formula One Racecar Team, did a semester long co-op working on fume hoods, did a summer internship at Kimberly Clark designing a HVAC system, and did another summer internship at General Electric designing anesthesia equipment. As a senior, I got involved in research doing finite element analyses of a prosthetic foot. This immediately got me hooked on applying engineering to medical applications.

I obtained my Biomedical Engineering PhD at the University of Wisconsin-Madison. My work focused on computational biomechanics. More specifically, developing musculoskeletal models of the body to simulate movement and see how surgery and soft tissue injury affects movement. During my graduate work, I was also a teaching assistant for Introduction to Biomechanics where I developed a love for teaching. I then did postdoctoral research at the University of Kentucky where I experimentally measured movements (e.g running form), which provides data that can be used to validate the models I build. At Gannon University, I built computational models with a focus on the knee to optimize surgical techniques (e.g. ACL reconstruction) to restore normal function after injury. At UW-Stout, my research area is on 3D printing techniques. Specifically I am working on the reliability of the 3D printing process to create functional parts. When I'm not doing research, I enjoy going swimming, camping with my kids in Scouts, and playing my violin.

Authors:

Anne Schmitz UW Stout