Final Project Report (1)
- 1. Final Project Report ENSC 29 – Child AFO Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 2. Project Overview Improve the manufacturing process of child AFOs AFO: Ankle Foot Orthosis Current process involves fabrication of mold, vacuum heat forming of solid polypropylene sheet 3D printing cuts time and cost Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 3. Purpose Reduce time and cost of producing AFOs Materials research to help determine optimal printing materials Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 4. Materials Testing Materials to test PLA Polypropylene Carbon Fiber PLA PETG Nylon MTS and Fatigue Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 5. Deliverables Full scale AFO print (PLA and PETG) Materials research results Material recommendation Printing process overview Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 6. 3D Scanner Leg is first casted out of plaster Cast is 3D scanned Spectra Scanner Resolution: 100 microns (100 μm) CanFit software can modify model Exports a 2D surface (.stl file type) Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 7. Meshmixer Converts 2D surface in 3D space to 3D model Extrudes surface normal to the surface Designate the extrusion thickness Objective: 3mm Export as an .stl Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 8. Simplify3D 3D AFO placed onto virtual print bed Print settings based on material Nozzle and bed temperatures Raft and support material 100% Infill for solid walls Material Presets for ease of use Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 9. 3D Printing .gcode sent to printer Printer head and print bed heat up to desired temperatures Monitor first layer and adjust z axis offset for good bed adhesion Return ~16 hours for completed print Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 10. Testing Methods MTS Machine Measures: Tensile Strength and Young’s Modulus Fatigue Tester Measures: Withstands cycles of bending forces before failure Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 11. Polylactic Acid (PLA) Pros: Printability cost Cons: Concerns about brittleness Biodegradability is a factor Exposure to UV radiation, humidity over time Verdict: Great for rapid prototyping and awesome repeatability, long-term viability may be a concern Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 12. Carbon Fiber PLA Overall results were inconclusive Only one attempt was made Adjusting printer settings could yield a workable product Pros: High strength Aesthetics Cons: Poor fatigue results Extreme brittleness Possibility of shattering, causing patient harm Verdict: Complete print of AFO is feasible, but extreme brittleness makes it difficult to recommend Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 13. 3DP Polypropylene Pros: Properties closest to original material Very easy to load into printer Cons: Does not stick to bed Glass transition temperature is less than room temperature No printers currently use cooled beds Major warping, layers do not stick together Verdict: Until 3D printing technology advances, polypropylene not feasible for nonindustrial applications Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 14. Polyethylene Terephthalate Glycol (PETG) Pros: Highest average ranking Very printable, great repeatability Good compromise between strength and flexibility Relatively inexpensive Cons: High-tendency to split after long-term use "Eyeball flex test" Verdict: A great compromise between properties, great for rapid prototyping, long-term viability may not be possible Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 15. Nylon Printed with PCTPE nylon 680 would have been preferred Pros: Fairly repeatable prints Cons: Extremely low modulus Not enough support Requires baking before or after printing Absorbs moisture during long prints Most expensive (even more for 680) Verdict: While 680 nylon preferable, inferior properties may make it infeasible for AFOs; price and preparation time are also negatives Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 16. Testing Results Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 17. Materials Summary Objectively PETG seems to be the best material Average ranking do not take into account subjective categories Comfort Amount of support Aesthetics Did find out a lot about what could work and what most likely will not Interesting comparison of materials, importance of compromise Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 18. Recommendation PLA: Very good for rapid prototyping, we would recommend it as a material to test fits quickly before sending out for a finalized product PETG: Much better than PLA, we would recommend for temporary use, or possibly a final product with further testing Nylon: We didn't have time to comprehensively test every variation of nylon, there is a possibility one of them would work Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 19. Implementation Issues Materials: We knew going into this project that we may not find a way of printing this product with a material that met our requirements Testing: We also knew going in that we would not have a clear way of testing our full scale printed AFO, and we had limited resources and time (no 3-point-bend test or patient testing) Software: We did not have any idea how much time would be spent looking for software to do the simple task of extruding our scan into a printable product Printer issues: Due to prints run by the university, the printer was unusable for several days Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 20. Cost Analysis Time Savings Current Process: 3D Scan sent to Portland-> Foam Positive Mold -> Rough Cut AFO -> Ship back to Shriners Hospital -> Final Adjustments Total Time: ~2 weeks 3D-Printed Process: 3D Scan -> Extruded in Meshmixer -> Print process set-up in Simplify3D -> 3D print Total Time: ~16 hours Additional Notes Multiple prints can be made simultaneously for different fits Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 21. Cost Analysis cont. Cost Savings Limited Information from Shriners regarding overall cost (manufacturing, staffing, etc.) 3D printing only uses the required material. (~0.5 kg per AFO) 3D printing is not labor intensive. 3D printed materials are relatively cheap and will continue to decrease in price with the growing interest in the technology. Cheap PLA 3D printed prototypes can be made to test fit with the patient before using a more expensive material for the final product. Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 22. Project Conclusion Is it possible to 3D print an AFO to scale? Yes Will it save the hospital time and money over time? Yes Will PLA/PETG meet patient needs? Insufficient data Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29
- 23. Future Projects Advancement of 3D-printing technology Blended materials Polypropylene-compatible printers Innovative geometries Modifications to existing AFOs Varying thicknesses Combinations of materials Optimized material testing 3-point bend test Volunteer test subjects? Shane Derrick | McKenzie Horner | Colin Le | Quinn Walters ENSC 29