TRAINING IN THE FIELD OF POLYMER MATERIALS / PLASTICS Influence of material data on injection moulding simulation Application examples Ass.Prof. Dr. Thomas Lucyshyn 24 th April 2014 Otto Gloeckel-Straße 2, A-8700 Leoben, Tel.: +43 3842 402 3501 kv@unileoben.ac.at www.kunststofftechnik.at
Content Introduction Melt Flow Rate (MFR) as reference value for viscosity Pressure dependence of viscosity Transition temperature Thermal conductivity and specific heat capacity pvt-data at different cooling rates Summary www.kunststofftechnik.at Thomas Lucyshyn 2
Content Introduction Melt Flow Rate (MFR) as reference value for viscosity Pressure dependence of viscosity Transition temperature Thermal conductivity and specific heat capacity pvt-data at different cooling rates Summary www.kunststofftechnik.at Thomas Lucyshyn 3
Required material data Viscosity as a function of Shear rate, temperature and optionally pressure Transition temperature T trans Thermal conductivity (ideally temperature dependent) Specific heat (ideally temperature dependent) pvt-data Mechanical properties Young s modulus, Poisson ratio, shear modulus, coefficient of linear thermal expansion Fibre properties www.kunststofftechnik.at Thomas Lucyshyn 4
Material data for injection moulding simulation Source: Internet www.kunststofftechnik.at Thomas Lucyshyn 5
Content Introduction Melt Flow Rate (MFR) as reference value for viscosity Pressure dependence of viscosity Transition temperature Thermal conductivity and specific heat capacity pvt-data at different cooling rates Summary www.kunststofftechnik.at Thomas Lucyshyn 6
Measuring method of MFR Weight Nozzle: Weight (mass): Shear stress: Piston Sample Heating Nozzle Shear rate: MFR: Melt mass flow rate in g/10min MVR: Melt volume flow rate in cm³/10min Viscosity: Source according to: Waßner, E.: Rheologische Grundlagen für die Auslegung von Extrusionswerkzeugen, VDI-Praktikum: Werkzeugauslegung mit Excel, Paderborn, 2003. www.kunststofftechnik.at Thomas Lucyshyn 7
MFR as reference value for viscosity? www.kunststofftechnik.at Thomas Lucyshyn 8
log MFR for comparing materials? Material A Material B MFR MFR of A = MFR of B log Rheological behaviour of A = Rheological behaviour of B? www.kunststofftechnik.at Thomas Lucyshyn 9
Example: pressure calculation at same MFR 2 unfilled POM-grades of same supplier www.kunststofftechnik.at Thomas Lucyshyn 10
Viscosity curves of the two POM-grades www.kunststofftechnik.at Thomas Lucyshyn 11
Part for simulation Square box 100 x 100 x 40 mm³ (1 mm wall thickness) Hot runner with central gate at the bottom www.kunststofftechnik.at Thomas Lucyshyn 12
Pressure at swich over point (filling pressure) Hostaform s9363 25% Celcon M50-14 1185 bar 1476 bar www.kunststofftechnik.at Thomas Lucyshyn 13
Content Introduction Melt Flow Rate (MFR) as reference value for viscosity Pressure dependence of viscosity Transition temperature Thermal conductivity and specific heat capacity pvt-data at different cooling rates Summary www.kunststofftechnik.at Thomas Lucyshyn 14
Cross-WLF-equation in Moldflow www.kunststofftechnik.at Thomas Lucyshyn 15
Cross-WLF-equation in Moldflow 0 0 1n 0 (8) 1 D 1 exp A A1 T T * T T * 2 T* D2 D3 p A 2 ~ A2 D3 p Pressure dependence! Approx. 8.800 thermoplastics in Moldflow 2014, of which about 100 materials with D3 www.kunststofftechnik.at Thomas Lucyshyn 16
Cross-WLF-equation in Moldflow 0 pressure A 0 1 B C 0 1 1n temperature 1-n * 0 www.kunststofftechnik.at Thomas Lucyshyn 17
Part: thin walled bush Injection pressure at the injection moulding machine: 2400 bar Wall thickness about 0,4 to 0,8 mm www.kunststofftechnik.at Thomas Lucyshyn 18
Viscosity in Pa*s Measuring results of pressure dependent viscosity 1000 bar 1 bar Shear rate in s -1 www.kunststofftechnik.at Thomas Lucyshyn 19
Calucations with and without pressure dependence Without pressure dependence With pressure dependence www.kunststofftechnik.at Thomas Lucyshyn 20
Pressure at switch-over point (injection pressure) Without pressure dependence With pressure dependence 1284 bar 85% 2368 bar www.kunststofftechnik.at Thomas Lucyshyn 21
Content Introduction Melt Flow Rate (MFR) as reference value for viscosity Pressure dependence of viscosity Transition temperature Thermal conductivity and specific heat capacity pvt-data at different cooling rates Summary www.kunststofftechnik.at Thomas Lucyshyn 22
Transition temperature (No-Flow) Experimental determination DSC-Measurement (Differential Scanning Calorimetry) In cooling mode at -20 K/min Determination of the onset temperature Capillary rheometer (not used any more) Melt polymer turn off heating piston with constant load squeeze out melt until strand speed = 2mm/min (equals 0,033 mm/s!) Further (less frequent) methods: Adapted injection moulding machine Pressure measurement at capillary rheometer Cone-plate-rheometer www.kunststofftechnik.at Thomas Lucyshyn 23
Transition temperature with DSC oven chamber DSC sample and reference Source: Mettler Toledo AG, CH www.kunststofftechnik.at Thomas Lucyshyn 24
H (mw) Transition temp. of a semi-crystalline polymer 80 70 60 Cooling mode 50 40 PP cooling rate -20 K/min 30 20 10 0 20 40 60 80 100 120 140 160 180 200 T ( C) Hostacom BR 735 G Transition temperature Heat flow H as a function of temperature T Source: T. Lucyshyn, G. Knapp, M. Kipperer, C. Holzer: Determination of the Transition Temperature at Different Cooling Rates and Its Influence on Prediction of Shrinkage and Warpage in Injection Molding Simulation. Journal of Applied Polymer Science, 2012, 123, S.1162-1168. www.kunststofftechnik.at Thomas Lucyshyn 25
Transition temp. of an amorphous polymer Cooling mode ABS (cooling rate -20 K/min) Transition temperature (point of inflection) Source: T. Lucyshyn, G. Knapp, M. Kipperer, C. Holzer: Determination of the Transition Temperature at Different Cooling Rates and Its Influence on Prediction of Shrinkage and Warpage in Injection Molding Simulation. Journal of Applied Polymer Science, 2012, 123, S.1162-1168. www.kunststofftechnik.at Thomas Lucyshyn 26
H (mw) Heat flux at different cooling rates for PP 80 5 K/min 70 10 K/min 20 K/min 60 40 K/min 50 K/min 50 40 30 20 10 0 20 40 60 80 100 120 140 160 180 200 T ( C) Hostacom BR 735 G Source: T. Lucyshyn, G. Knapp, M. Kipperer, C. Holzer: Determination of the Transition Temperature at Different Cooling Rates and Its Influence on Prediction of Shrinkage and Warpage in Injection Molding Simulation. Journal of Applied Polymer Science, 2012, 123, S.1162-1168. www.kunststofftechnik.at Thomas Lucyshyn 27
Ttrans (K) Transition temp. as a function of cooling rate for PP 410 405 400 Ttrans T trans a T t b 395 390 385 Parameter PP Hostacom BR 735 G a (min b K (1-b) ) 415,4 b (-) -0,0148 380 0 10 20 30 40 50 60 70 80 90 100 110 Cooling rate (K/min) Hostacom BR 735 G Correlation coefficient R 2 0,983 Source: T. Lucyshyn, G. Knapp, M. Kipperer, C. Holzer: Determination of the Transition Temperature at Different Cooling Rates and Its Influence on Prediction of Shrinkage and Warpage in Injection Molding Simulation. Journal of Applied Polymer Science, 2012, 123, S.1162-1168. www.kunststofftechnik.at Thomas Lucyshyn 28
Box for simulation and experiments 100 x 100 x 40 mm³ Source: T. Lucyshyn, G. Knapp, M. Kipperer, C. Holzer: Determination of the Transition Temperature at Different Cooling Rates and Its Influence on Prediction of Shrinkage and Warpage in Injection Molding Simulation. Journal of Applied Polymer Science, 2012, 123, S.1162-1168. www.kunststofftechnik.at Thomas Lucyshyn 29
Deformation (%) Results for warpage simulation for PP 4,0 3,5 3,0 2,5 2,0 1,5 L1 experiment L2 experiment L3 experiment H1 experiment H2 experiment L1 simulation L2 simulation L3 simulation H1 simulation H2 simulation 1,0 0,5 Box: 1 mm wall thickness 0,0 10 20 30 40 50 60 70 80 90 100 110 Cooling rate (K/min) Hostacom BR 735 G 3D Source: T. Lucyshyn, G. Knapp, M. Kipperer, C. Holzer: Determination of the Transition Temperature at Different Cooling Rates and Its Influence on Prediction of Shrinkage and Warpage in Injection Molding Simulation. Journal of Applied Polymer Science, 2012, 123, S.1162-1168. www.kunststofftechnik.at Thomas Lucyshyn 30
Content Introduction Melt Flow Rate (MFR) as reference value for viscosity Pressure dependence of viscosity Transition temperature Thermal conductivity and specific heat capacity pvt-data at different cooling rates Summary www.kunststofftechnik.at Thomas Lucyshyn 31
Thermal conductivity (W/mK) Wärmeleitfähigkeit [W/mK] Thermal conductivity (W/mK) Wärmeleitfähigkeit [W/mK] Thermal conductivity Semi-crystalline thermoplastics Amorphous thermoplastics 0,4 0,3 PP PA POM 0,3 0,2 0,2 0,1 0,1 PS ABS 0 0 50 100 150 200 250 300 350 Temperatur [ C] Temperature ( C) 0 0 50 100 150 200 250 300 350 Temperatur [ C] Temperature ( C) PC Source: T. Kisslinger: Einfluss der thermischen Stoffdaten auf Berechnungsergebnisse in Moldflow Plastics Insight (MPI), Studienarbeit am Institut für Kunststoffverarbeitung, Montanuniversität Leoben, 2007. www.kunststofftechnik.at Thomas Lucyshyn 32
Cp [J/KgK] c p (J/kgK) c p (J/kgK) Cp [J/KgK] Specific heat capacity (c p ) Semi-crystalline thermoplastics Amorphous thermoplastics 16000 12000 8000 PP PA POM 2500 2000 1500 4000 1000 500 PS ABS 0 0 50 100 150 200 250 300 350 Temperature [ C] ( C) PC 0 0 50 100 150 200 250 300 350 Temperatur [ C] Temperature ( C) Source: T. Kisslinger: Einfluss der thermischen Stoffdaten auf Berechnungsergebnisse in Moldflow Plastics Insight (MPI), Studienarbeit am Institut für Kunststoffverarbeitung, Montanuniversität Leoben, 2007. www.kunststofftechnik.at Thomas Lucyshyn 33
Thermal conductivity (W/mK) Wärmeleitfähigkeit [W/mK] c p (J/kgK) Cp [J/KgK] Single values temperature dependent values Single value of specific heat at melt temperature (example for PP) 16000 12000 8000 4000 0 0 50 100 150 200 250 300 Temperatur [ C] Temperature ( C) Single value of thermal conductivity at melt temperature (example for PP) 0,3 0,25 0,2 0,15 0,1 0,05 0 0 50 100 150 200 250 300 Temperatur [ C] Temperature ( C) Source: T. Kisslinger: Einfluss der thermischen Stoffdaten auf Berechnungsergebnisse in Moldflow Plastics Insight (MPI), Studienarbeit am Institut für Kunststoffverarbeitung, Montanuniversität Leoben, 2007. www.kunststofftechnik.at Thomas Lucyshyn 34
Influence on cycle time Temperature of hottest region in part over time Time to reach ejection temperature evaluated Investigated region of part Source: T. Kisslinger: Einfluss der thermischen Stoffdaten auf Berechnungsergebnisse in Moldflow Plastics Insight (MPI), Studienarbeit am Institut für Kunststoffverarbeitung, Montanuniversität Leoben, 2007. www.kunststofftechnik.at Thomas Lucyshyn 35
Time (s) Example PP, 3 mm wall thickness Influence on cycle time Mesh variations Source: T. Kisslinger: Einfluss der thermischen Stoffdaten auf Berechnungsergebnisse in Moldflow Plastics Insight (MPI), Studienarbeit am Institut für Kunststoffverarbeitung, Montanuniversität Leoben, 2007. www.kunststofftechnik.at Thomas Lucyshyn 36
Time (s) Zeit [sec] Example PS, 3 mm wall thickness Influence on cycle time 35,00 λ(t) cp(t) 30,00 25,00 20,00 λ(t) cp λ cp(t) λ cp 18,08 21,65 17,28 20,63 22,16 29,02 20,41 25,02 15,00 10,00 5,00 0,00 PS Fusion 3mm PS 3D 3mm Berechnungsvarianten Mesh variations Source: T. Kisslinger: Einfluss der thermischen Stoffdaten auf Berechnungsergebnisse in Moldflow Plastics Insight (MPI), Studienarbeit am Institut für Kunststoffverarbeitung, Montanuniversität Leoben, 2007. www.kunststofftechnik.at Thomas Lucyshyn 37
Content Introduction Melt Flow Rate (MFR) as reference value for viscosity Pressure dependence of viscosity Transition temperature Thermal conductivity and specific heat capacity pvt-data at different cooling rates Summary www.kunststofftechnik.at Thomas Lucyshyn 38
pvt-data Amorphous polymer Specific volume (cm³/g) Semi-crystalline polymer Specific volume (cm³/g) melt melt solid solid Transition temperature Transition temperature Temperature ( C) Temperature ( C) Source according to: Kennedy, P.: Flow Analysis of Injection Molds; Carl Hanser Verlag, München, 1995. www.kunststofftechnik.at Thomas Lucyshyn 39
Standard measurement method for pvt-data Cooling rate of approx. 0,1 K/s (6 K/min) v p, T l r m 2 www.kunststofftechnik.at Thomas Lucyshyn 40
high cooling rate (hcr) pvt-device IR-sensor Oven Thermocouple Ejector piston IR-sensor Cooling channels Cooling rates up to 15 K/s Measuring cell Stroke transducer Polymer sample Cooling channels Piston Pressure transducer in hydraulic system Source: T. Lucyshyn: Messung von pvt-daten bei prozessnahen Abkühlraten und deren Einfluss auf die Simulation von Schwindung und Verzug mit Moldflow Plastics Insight, Dissertation an der Montanuniversität Leoben, 2009. www.kunststofftechnik.at Thomas Lucyshyn 41
Spezifisches Volumen in cm³/g Specific volume (cm³/g) Results of hcr-pvt-device for ABS 1,06 1,04 ABS 1,02 1,00 0,98 0,96 200 bar hcr-pvt 400 bar hcr-pvt 600 bar hcr-pvt 800 bar hcr-pvt 200 bar MPI 400 bar MPI 600 bar MPI 800 bar MPI Ca. 13 K/s Ca. 0,1 K/s 0,94 0,92 0 50 100 150 200 250 Temperature in ( C) 2,3 mm sample Source: T. Lucyshyn: Messung von pvt-daten bei prozessnahen Abkühlraten und deren Einfluss auf die Simulation von Schwindung und Verzug mit Moldflow Plastics Insight, Dissertation an der Montanuniversität Leoben, 2009. www.kunststofftechnik.at Thomas Lucyshyn 42
Spez. Volumen in cm³/g Specific volume (cm³/g) Results of hcr-pvt-device for PP 1,12 1,10 PP 1,08 1,06 1,04 1,02 1,00 0,98 400 bar hcr-pvt 600 bar hcr-pvt 800 bar hcr-pvt 400 bar MPI 600 bar MPI 800 bar MPI Ca. 15 K/s Ca. 0,1 K/s 0,96 0,94 0 50 100 150 200 250 Temperature in ( C) 2 mm Probe Source: T. Lucyshyn: Messung von pvt-daten bei prozessnahen Abkühlraten und deren Einfluss auf die Simulation von Schwindung und Verzug mit Moldflow Plastics Insight, Dissertation an der Montanuniversität Leoben, 2009. www.kunststofftechnik.at Thomas Lucyshyn 43
Deformation in % Simulation results for ABS 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0 L1 L2 L3 H1 H2 Reference Vergleichsmaße dimensions ABS, 3D-Model Standard pvt hcr-pvt Experiment Source: T. Lucyshyn: Messung von pvt-daten bei prozessnahen Abkühlraten und deren Einfluss auf die Simulation von Schwindung und Verzug mit Moldflow Plastics Insight, Dissertation an der Montanuniversität Leoben, 2009. www.kunststofftechnik.at Thomas Lucyshyn 44
Deformation in % Simulation results for PP 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0 L1 L2 L3 H1 H2 Vergleichsmaße Reference dimensions Standard pvt hcr-pvt Experiment PP, 3D-Model Source: T. Lucyshyn: Messung von pvt-daten bei prozessnahen Abkühlraten und deren Einfluss auf die Simulation von Schwindung und Verzug mit Moldflow Plastics Insight, Dissertation an der Montanuniversität Leoben, 2009. www.kunststofftechnik.at Thomas Lucyshyn 45
Content Introduction Melt Flow Rate (MFR) as reference value for viscosity Pressure dependence of viscosity Transition temperature Thermal conductivity and specific heat capacity pvt-data at different cooling rates Summary www.kunststofftechnik.at Thomas Lucyshyn 46
Summary 1 Complex material data required for simulation Melt Flow Rate (MFR) as reference value for viscosity? Good orientation for limitation of potential similar materials Important: compare viscosity curves! Example: pressure difference of 25% at same MFR Pressure dependence of viscosity Viscosity increases with increasing pressure Especially important for thin walled parts Relevant at expected injection pressures > 1000 bar Example: pressure difference of 85% www.kunststofftechnik.at Thomas Lucyshyn 47
Transition temperature Summary 2 Determined with DSC measurement Cooling rate has influence on transition temperature Transition temperature has influence on warpage results Temperature dependent thermal data Significant differences between single point data and temperature dependent data Especially cycle time differs by up to 15% pvt-data Cooling rate has influence on pvt-curves Improved shrinkage simulation with pvt-data obtained at process near cooling rates www.kunststofftechnik.at Thomas Lucyshyn 48
Thank you for your attention! Contact: Ass.Prof. Dr. Thomas Lucyshyn Chair of Polymer Processing Montanuniversitaet Leoben Otto Gloeckel-Str. 2 8700 Leoben 03842 / 402 3510 thomas.lucyshyn@unileoben.ac.at www.kunststofftechnik.at Thomas Lucyshyn 49