Design for Micro Molding: Guidelines, Challenges, and Pushing the Limits Aaron Johnson, VP Marketing Accumold SmartManufacturingSeries.com
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Design for Micro Molding: Guidelines, Challenges, and Pushing the Limits 1. What is Micro Molding? 2. What makes it special? 3. Are there any guidelines? 4. What are some of the challenges? 5. What can I do with Micro Molding?
What is Micro Molding?
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Set-up for success, not just one part.
Guidelines Understanding the Rules: Gates as small as 0.1mm Ejector pins as small as.25mm Aspect ratios around 6:1 (material dependent) Be mindful of thick-to-thin wall transitions Watch wall thickness uniformity Ribs as a % of wall thickness Know how shrink rates will affect the part Understand parting line mismatch Flash & Witness Marks Draft is still welcomed 300µm Ø300µm
Challenge: Prototyping: CASE STUDY Ø.010 (0.254mm) 250µ Ø aspheric lens High-Polished Surface Artwork height.001 (0.0254mm) Prototyping Technologies Stereolithography(SLA) 3D Printing PolyJet Fusion Deposition Modeling (FDM) Selective Laser Sintering (SLS) Laminated Object Manufacturing (LOM) Cast Urethanes Machining/Rapid Tooling Rapid Injection Molding (RIM) Standard Hard Tooling L.015 (0.38mm) x W.006 (0.152mm) Ø.020 (0.508mm) L.005 (0.127mm) x W.0025 (0.0635mm) L.200 (5.08mm) x W.200 (5.08mm) x H.125 (3.175mm)
Challenge: Prototyping: CASE STUDY Results SLA Machined SLA Machined PolyJet Micro-Mold PolyJet Micro-Mold
SLA PolyJet Machined Micro-Mold Challenge: Prototyping: CASE STUDY Results
Challenge: Material Selection & Feature Performance Gate Materials PEEK, Ultem, LCP Nylon TPE / TPU Filled materials: glass, carbon Optical Grades Medical / Implantable Grades Attenuated Materials Specialty Materials Accumold Part
Challenge: Material Selection & Feature Performance: CASE STUDY.1276 (3.241mm) 42:1 Max Aspect Ratio Gate Location.200 (5.08mm).003 (76µm) The relationship between material selection and feature performance at the micro scale. The Resins 1. Polyethylene (PE) 2. Polypropylene (PP) 3. Polyamide (Nylon) 4. Polycarbonate (PC) 5. Polysulfone(PSU) 6. Polyoxymethylene(POM) 7. Polybutylene Terephthalate (PBT) 8. Polymethyl Methacrylate (PMMA) 9. Polyether Ether Ketone (PEEK) 10. Polyetherimide(PEI) 11. Liquid Crystal Polymer (LCP)
Challenge: Material Selection & Feature Performance: CASE STUDY Picking your material: Where Do You Turn for Expertise? The wall thickness would require an increase of 5x to 10x the current.003 in order to fill. Molding the part thicker and grind it down to the desired thickness. In looking at the part, the.003 section will not fill any of the listed materials. In fact, I believe you will be hard pressed to find a thermoplastic material that would fill that.0127 long,.003 wall. I do believe you would need to be in the.015 wall thickness zone. We would suggest increasing the.003 wall thickness to at least.015 or, better yet,.030 in order to improve moldability. In my opinion filling this geometry would not be possible in a production environment. I would consider trying to mold a PP at approximately.016 -.018 and an Acetal 9 melt at.025.
Challenge: Material Selection & Feature Performance: CASE STUDY: RESULTS Polyethylene (PE) Polypropylene (PP) Liquid Crystal Polymer (LCP) Polyoxymethyle ne (POM) Polymethyl Methacrylate (PMMA) 42:1 42:1 42:1 42:1 26:1 Polybutylene Terephthalate (PBT) Polyamide (Nylon) Polycarbonate (PC) Polysulfone (PSU) Polyetherimide (PEI) 25:1 18:1 14:1 14:1 10:1 Polyether Ether Ketone (PEEK) 3:1 Material selection alone can have a profound effect on feature performance..003 (76µm) Thin Wall * Full length.1276 (3.241mm)
Challenge: Material Selection & Feature Performance 70µm Ø 100µm lens w/ 125µm base radius PEI (Ultem )
Challenge: Metrology, Handling, & Packaging Packaging Metrology 250µ 250µ Quest 450 Zygo 7300 Handling High Speed Automation 24 Cavity with 2 pairs of lead-strip. Each pair of lead-strip was crimped and fed thru the mold. The molded product was then fed to a testing and singulation die for packaging. The system had an annual volume of 30M parts.
Pushing the Limits: What can you do with Micro Molding? Micro-Molding Alignment Spacer 800µm x 380µm x 300µm Material: LCP This part is made of LCP and is Accumold s smallest commercial part to date. It measures 800µm x 380µm x 360um. 144,000 parts weigh 1 oz. Part handling more of an issue with this part than the tool build and production.
Pushing the Limits : What can you do with Micro Molding? 2-Shot Micro-Molding Connector Seal Soft TPU Ring Saved Labor The hard, clear ABS part is combined with the sof t, white TPU material to create a perf ect bond. This process saved manuf acturing resources and replaced the assembly and gluing process for the end customer.
Pushing the Limits : What can you do with Micro Molding? Overmold Medical Flex-Circuit Overmolding Material TPE This part requires delicate handling of the f lex circuit during processing. Careful shut-offs on the mold were require to not damage the circuit. The two orange parts are molded simultaneously with a dual gate setup.
Pushing the Limits : What can you do with Micro Molding? Micro-Molding Insert Molding Singulation Die-Intergrated Delicate Insert Media This part shows an example of advanced insert molding capabilities where a delicate filter was molded into a plastic housing. This required the mold to be built in such a precise fashion so that the insert material could articulate through the mold during processing and not be destroyed in the process while keeping the tolerances tight within the part itself. The part is approximately 2mm in diameter.
Pushing the Limits : What can you do with Micro Molding? Complex Micro Molding Hand-loaded Inserts Unique Multi-Slide Design Special Packaging These two parts are internal chassis f or hearing instruments. The v ery complex larger part on the bottom has 3 discreet pins that are ov ermolded simultaneously. The smaller part at the top has 5 discrete contacts that are overmolded as well.
Technology Highlight: MSE: Micro Structure Enhancement Ø 400µm x 12µm tall Ø 25µm x 1µm tall Ø 10µm x 0.5µm tall
Technology Highlight: LDS: Laser Direct Structuring / 3D-MID Examples: Molded Part Activated additive by Laser ablation Laser Traced Laser 2-Shot Non-Laser Process Plated Part CAD Design: Modified Polymer
Thank You! QUESTIONS? SmartManufacturingSeries.com