Injection moulding and modelling on a micro scale Technology Update Injection moulding and welding of plastics 11 November 2014 Research Projects (National / European) Micro/Nano/Multimaterial Manufacturing POLYMETAL DK (2005 2008) Metallization of polymers for micro manufacturing MASMICRO EU FP6 (2004 2008) Micro assembly techniques for micro products 4M EU FP6 (2004 2008) Multi Material Micro Manufacture NANOCMM EU FP6 (2006 2012) Coordinate Metrology for Micro Components Production COTECH EU FP7 (2008 2012) Converging Technologies for Micro Manufacture PolyNano DK (2011 2015) for Micro/Nano Fluidic Manufacturing Platform Innomold DK (2012 2015) Innovative Moulding Technologies Hi Micro EU FP7 (2012 2015) High Precision Technology for Micro Manufacture HINMICO EU FP7 (2013 2016) High Throughput Integrated Technologies for Multi material Functional Micro Components 2 DTU Mechanical Engineering, Technical University of Denmark 1
Now: Associate professor on Micro/Nano Polymer Processing 2005 2008 PhD project at DTU Mechanical Engineering on Micro Injection Moulding (µim) 3 DTU Mechanical Engineering, Technical University of Denmark Section of Manufacturing Engineering Injection Moulding (IM), Micro Injection Moulding (µim), Injection Compression Moulding (ICM) RESEARCH: Process development Process simulation Design & Tooling 4 DTU Mechanical Engineering, Technical University of Denmark 2
Section of Manufacturing Engineering Laboratory of Geometrical Metrology 5 DTU Mechanical Engineering, Technical University of Denmark Precision injection moulding of polymer micro/nano geometries 1,0E 03 CURRENT STATE OF THE ART Replication studies Calibration of µ n geometries Mould Polymer Process Investigation Optimization Simulation Vertical dimension [m] 1,0E 04 1,0E 05 1,0E 06 1,0E 07 1,0E 08 Hot Embossing Injection Compression Moulding Injection Moulding µ Injection Moulding Soft Lithography 1,0E 09 1,0E 09 1,0E 08 1,0E 07 1,0E 06 1,0E 05 1,0E 04 1,0E 03 Lateral dimension [m] [Hansen, Hocken, Tosello, Replication of micro and nano surface geometries, CIRP Key Note STC S, 2011] 6 DTU Mechanical Engineering, Technical University of Denmark 3
7 DTU Mechanical Engineering, Technical University of Denmark mm µm nm SIZE FEATURES TOLE RANCES 8 DTU Mechanical Engineering, Technical University of Denmark 4
Outline (1) Injection moulding of surface micro nano structures (2) Injection moulding of surface micro nano structures (3) Injection moulding of optical micro components (4) Injection moulding of micro components (5) Injection moulding and simulation of thin wall moulded parts (6) Injection moulding of micro components with micro features (7) Injection moulding and simulation of miniaturized precision parts (8) Multi material micro injection moulding simulation 9 DTU Mechanical Engineering, Technical University of Denmark no. 1 mm µm nm SIZE FEATURES TOLE RANCES 10 DTU Mechanical Engineering, Technical University of Denmark 5
Precision injection molding of surface micro nano structures Full electric injection molding machine: Screw diameter of 18mm Clamping force 600 kn Repeatability (std deviation) 0,8 mg Cylclic Olefin Copolymer (COC): Cyclic Olefin Copolymer, COC TOPAS 6013 High heat deflection, chemical resistance possible parts sterilization 11 DTU Mechanical Engineering, Technical University of Denmark Dimensional measurements and Tolerance Verification Product compliance with specification Quality control Process chain capability (Uncertainty) Tolerance limits Etched silicon master geometries Nickel electroplated geometries Injection moulding replica AFM measurements (magnification: X 1x, Y 1x, Z 5x) 12 DTU Mechanical Engineering, Technical University of Denmark 6
Dimensional measurements and Tolerance Verification Crosses channels depth [nm] 70 68 66 64 62 60 58 56 54 52 50 Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Silicon Wafer Nickel Shim Polymer Samples Sample 9 Largest depth deviation among the different polymer sample is equal to 7nm Average polymer channel depth replication fidelity equal to 94% 13 DTU Mechanical Engineering, Technical University of Denmark Process monitoring Injection pressure (based on machine measurements) Injection pressure - Repeatability test 800 700 Injection pressure [bar] 600 500 400 300 200 100 Test 1 Test 2 Test 3 Test 4 Test 5 Test 6 Test 7 Test 8 Test 9 Test 10 0 0 50 100 150 200 250 Injection time [ms] 14 DTU Mechanical Engineering, Technical University of Denmark 7
no. 2 mm µm nm SIZE FEATURES TOLE RANCES 15 DTU Mechanical Engineering, Technical University of Denmark Methodology SEM image processing & AFM measurements CD 16 DTU Mechanical Engineering, Technical University of Denmark 8
Methodology SEM image processing & AFM measurements DVD 17 DTU Mechanical Engineering, Technical University of Denmark Methodology SEM image processing & AFM measurements HD DVD 18 DTU Mechanical Engineering, Technical University of Denmark 9
Injection moulding at µm nm scale 19 DTU Mechanical Engineering, Technical University of Denmark Replication assessment and tolerance verification at nm scale pit height Pit height [nm] 200 175 150 125 100 75 CD Replication 80% Height DVD Replication 88% Nickel stamper Polycarbonate disc Specification (tolerance) 50 25 0 HD-DVD Replication 100% CD DVD HD DVD 20 DTU Mechanical Engineering, Technical University of Denmark 10
Replication assessment and tolerance verification at nm scale track pitch 2000 1800 CD Replication 94% Track pitch Nickel stamper Track pitch [nm] 1600 1400 1200 1000 800 600 DVD Replication 100% Polycarbonate disc Specification (tolerance) HD-DVD Replication 100% 400 200 0 CD DVD HD DVD 21 DTU Mechanical Engineering, Technical University of Denmark no. 3 mm µm nm SIZE FEATURES TOLE RANCES 22 DTU Mechanical Engineering, Technical University of Denmark 11
Precision moulding of optical polymer micro geometries Micro structured optical component Ni mould PMMA part 23 DTU Mechanical Engineering, Technical University of Denmark Injection compression moulding PMMA part: made by injection compression moulding 1) INJECTION mould cavity partially open facilitate flow of plastic inside 2) COMPRESSION mould cavity reduction to real thickness of the component uniform distribution of the pressure into the mould cavity 24 DTU Mechanical Engineering, Technical University of Denmark 12
Injection compression moulded component B C I F E L A D H G 25 DTU Mechanical Engineering, Technical University of Denmark Pitch measurements SEM (Scanning Electron Microscope) analysis 1-2: vertical pitch 2-3: diagonal pitch 3-4: horizontal pitch Measurements on: Ni mould PMMA part 26 DTU Mechanical Engineering, Technical University of Denmark 13
Manufacturing Process Control Vertical pitch 255 Pitch 1-2 Ni PMMA 250 245 [µm] 240 235 230 225 220 A B C D E F G H I L 27 DTU Mechanical Engineering, Technical University of Denmark Manufacturing Process Control Diagonal pitch 225 Pitch 2-3 Ni PMMA 220 215 [µm] 210 205 200 195 190 A B C D E F G H I L 28 DTU Mechanical Engineering, Technical University of Denmark 14
Manufacturing Process Control Horizontal pitch 185 Pitch 3-4 Ni PMMA 180 175 [µm] 170 165 160 155 150 A B C D E F G H I L 29 DTU Mechanical Engineering, Technical University of Denmark Deviation [µm] Pitch measurement Absolute deviations Ni PMMA 18 16 14 12 10 8 6 B C I F E L A D H G 5-14 µm deviation Deviations depend on: Location Deviations decreasing With pitch length 4 2 0 A B C D E F G H I L Pitch 1-2 Pitch 2-3 Pitch 3-4 30 DTU Mechanical Engineering, Technical University of Denmark 15
Pitch measurement Relative deviations Ni PMMA 8 7 6 B C I F E L A D H G 2%-6% deviation Deviations independent from: Pitch direction Deviation [%] 5 4 3 2 1 0 Shrinkage locally isotropic Shrinkage anisotropic at component level A B C D E F G H I L Pitch 1-2 Pitch 2-3 Pitch 3-4 31 DTU Mechanical Engineering, Technical University of Denmark no. 4 mm µm nm SIZE FEATURES TOLE RANCES 32 DTU Mechanical Engineering, Technical University of Denmark 16
Case study Toggle for hearing aid application Heights 0.38 to 2.08 mm (T 0.02 0.04 mm) Diameters 1.55 0.02 mm; 5.4 0.03 mm Concentricity 0.02 mm Material POM Weight 35 mg Batch production >100 000 unit/year 33 DTU Mechanical Engineering, Technical University of Denmark Quality control Coordinate Measuring Machine 34 DTU Mechanical Engineering, Technical University of Denmark 17
Outer diameter D = 5400 30 µm U caltcmm (D) = 1.5µm 5430 5420 Outer diameter [µm] 5410 5400 5390 5380 5370 5360 5350 401 411 412 413 421 422 423 431 432 433 441 442 443 451 452 453 461 462 463 472 473 Sample number 35 DTU Mechanical Engineering, Technical University of Denmark Inner diameter d = 1550 20 µm U caltcmm (d) = 3.4µm 1570 1560 Inner diameter [µm] 1550 1540 1530 1520 1510 401 411 412 413 421 422 423 431 432 433 441 442 443 451 452 453 461 462 463 472 473 Sample number 36 DTU Mechanical Engineering, Technical University of Denmark 18
Concentricity C = (0, 20) µm U caltcmm (C) = 1.7µm 35 30 Outer diameter [µm] 25 20 15 10 5 0 401 411 412 413 421 422 423 431 432 433 441 442 443 451 452 453 461 462 463 472 473 Sample number 37 DTU Mechanical Engineering, Technical University of Denmark Height H = 380 30 µm U caltcmm (H) = 4.7µm 450 440 430 420 Height [µm] 410 400 390 380 370 360 350 401 411 412 413 421 422 423 431 432 433 441 442 443 451 452 453 461 462 463 472 473 Sample number 38 DTU Mechanical Engineering, Technical University of Denmark 19
no. 5 mm µm nm SIZE FEATURES TOLE RANCES 39 DTU Mechanical Engineering, Technical University of Denmark Injection moulding of precision thin wall parts Polymer: POM 40 DTU Mechanical Engineering, Technical University of Denmark 20
41 DTU Mechanical Engineering, Technical University of Denmark Warpage measurements No relaxation No deviations larger than std. dev. after: 24 hours 48 hours 7 days 7d 48h 24h POM Geo. a: Measurements L3 L2 0,80 0,70 0,60 0,50 0,40 0,30 0,20 0,10 0,00 Deviation [mm] 42 DTU Mechanical Engineering, Technical University of Denmark L1 H 21
Injection and cavity pressure Simulation vs. Experiments Pressure [bar] 1200 1000 800 600 400 200 POM Geo. a simulation P0 P1 P2 P3 0 0,00 0,50 1,00 1,50 2,00 Time [s] Pressure [bar] 1200 Experimental 1000 800 600 400 200 0 0,00 0,50 1,00 1,50 2,00 Time [s] 43 DTU Mechanical Engineering, Technical University of Denmark no. 6 mm µm nm SIZE FEATURES TOLE RANCES 44 DTU Mechanical Engineering, Technical University of Denmark 22
Precision Moulding of polymer microcomponents with micro features 2 cavities with micro structures Pressure sensor at injection location sample rate 25 khz one pressure sampling every 0.04 ms 50 mm 45 DTU Mechanical Engineering, Technical University of Denmark Pressure sensor mark 46 DTU Mechanical Engineering, Technical University of Denmark 23
Gate 47 DTU Mechanical Engineering, Technical University of Denmark 47 Micro features 48 DTU Mechanical Engineering, Technical University of Denmark 48 24
Micro injection moulding Cycle analysis and cavity filling time 500 450 Pressure at injection location [bar] 400 350 300 250 200 150 100 50 0 PRESSURE 130mm3 - exp1 PRESSURE 130mm3 - exp2 PRESSURE 130mm3 - exp3-50 0,400 0,420 0,440 0,460 0,480 0,500 0,520 0,540 0,560 0,580 0,600 Time [s] Cavity injection time 49 DTU Mechanical Engineering, Technical University of Denmark 0.060s no. 7 mm µm nm SIZE FEATURES TOLE RANCES 50 DTU Mechanical Engineering, Technical University of Denmark 25
Effect of process parameters on injection pressure Mean of Piston Injection Pressure [bar] 1600 1400 1200 1000 800 1600 1400 1200 1000 800 190 Tmelt Inj.Vel. 220 55 Tmould Stroke length 90 100 200 0,0 1,0 2,0 3,0 5,0 10,0 12,0 12,7 51 DTU Mechanical Engineering, Technical University of Denmark Injection pressure Coefficient of variation (COV%) of piston injection pressure 8 different process settings 14 different piston stroke lengths Sample for each discrete point = 20 measurements Piston injection pressure Coefficient of Variation (COV) [%] 12 10 8 6 4 2 Piston Injection Pressure Variation 190 C 55 C 100mm/s 220 C 55 C 100mm/s 190 C 90 C 100mm/s 220 C 90 C 100mm/s 190 C 55 C 200mm/s 220 C 55 C 200mm/s 190 C 90 C 200mm/s 220 C 90 C 200mm/s 0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 Piston stroke length [mm] 52 DTU Mechanical Engineering, Technical University of Denmark 26
Part length Effect of process parameters 11,68 Tmelt [ C] Tmold [ C] 11,67 11,66 Mean of LENGTH [mm] 11,65 11,64 11,68 11,67 190 InjVel [mm/s] 220 55 PackTime [s] 90 11,66 11,65 11,64 100 200 0,0 0,4 53 DTU Mechanical Engineering, Technical University of Denmark Part length STD DEV Effect of process parameters 0,016 Tmelt [ C] Tmold [ C] Mean of Std dev Length [mm] 0,014 0,012 0,010 0,016 0,014 190 InjVel [mm/s] 220 55 PackTime [s] 90 0,012 0,010 100 200 0,0 0,4 54 DTU Mechanical Engineering, Technical University of Denmark 27
Short shots & injection pressure 55 DTU Mechanical Engineering, Technical University of Denmark Injection Pressure Comparison Simulation vs. Experiments Pressure [MPa] 60 50 40 30 20 10 SIMULATION vs. EXPERIMENTAL SPRUE TIP INJ. PRESSURE Simulation Experimental 0 0 10 20 30 40 50 60 70 80 90 100 110 120 Injection Time [ms] 56 DTU Mechanical Engineering, Technical University of Denmark 28
no. 8 mm µm nm SIZE FEATURES TOLE RANCES 57 DTU Mechanical Engineering, Technical University of Denmark Multi material Micro Injection Moulding Simulation 2k 58 DTU Mechanical Engineering, Technical University of Denmark 29
Multi material Micro Injection Moulding Simulation 2k Flow pattern validation Shot 1 POM (white) 100% shot Shot 2 ABS (blue) short shots Experiments Simulation 59 DTU Mechanical Engineering, Technical University of Denmark s/o = 7.2 mm 5 mm 60 DTU Mechanical Engineering, Technical University of Denmark 60 30
5 mm 61 DTU Mechanical Engineering, Technical University of Denmark 61 s/o = 7.2 mm 62 DTU Mechanical Engineering, Technical University of Denmark 31
Flow pattern and micro features replication possible to be predicted by simulation 63 DTU Mechanical Engineering, Technical University of Denmark Key learnings Message to take home Injection moulding can produce features at micrometre level Injection moulding can produce features at 100 nm level Tolerances at micro/nano level can be obtained by injection moulding Simulation resolution can be achieved at 10 µm level Injection pressure and flow can be simulated with good accuracy Calibration is KEY PROCESS PRODUCTS MATERIALS MOULDS 64 DTU Mechanical Engineering, Technical University of Denmark 32
Thank you for your attention 65 DTU Mechanical Engineering, Technical University of Denmark 33