Proplast Kistler / Bt 2009 / 14th / Srr April 24 Sept 200809 29. September 2009 1
Zero Defect Manufacturing and Hot Runner Balancing based on Cavity Pressure Measurements Dr.-Ing Oliver Schnerr Head of Business Unit Plastics Kistler Instrumente AG Switzerland Proplast 2009 / Srr 24 Sept 09 29. September 2009 2
Overview Introduction Influences in Plastic Injection Molding Cavity Pressure Curve The Fingerprint of Injection Molding Zero Defect Manufacturing based on Cavity Pressure Automatic Hot Runner Balancing with Cavity Pressure Controlling Temperatures of Hot Runners Tools Summary Proplast 2009 / Srr 24 Sept 09 29. September 2009 3
Kistler Group Measuring technology company Development and production of sensors, electronics and systems for measuring pressure force torque acceleration Proplast 2009 / Srr 24 Sept 09 29. September 2009 43
Kistler Group International headquarters Winterthur, founded in 1959 Production in Switzerland, USA and Germany Active in over 50 countries worldwide 1000 employees around the world, 420 of whom are based in Switzerland Collaboration with over 50 universities Turnover 2008: 218 million Swiss Francs Proplast 2009 / Srr 24 Sept 09 29. September 2009 54
Kistler Group Stuttgart (Germany) Kistler Instrumente GmbH 50 employees Lorch (Germany) Kistler Staiger Mohilo 80 employees Stuttgart (Germany) Kistler-IGeL 35 employees Proplast 2009 / Srr 24 Sept 09 29. September 2009 65
Applications and Markets Plastics Engines Vehicles Manufacturing Biomechanics Proplast 2009 / Srr 24 Sept 09 20 7
Kistler Group Key Figures Turnover 2008: 218 million Swiss Francs Long-term average annual growth of 6 % 10 % of turnover reinvested in research and development Proplast 2009 / Srr 24 Sept 09 29. September 2009 87
Influences in Injection Molding Controller Deviations Material Deviations Operator Temperature Environmental conditions (Day/Night/ Humidity) Abrasion Proplast 2009 / Srr 24 Sept 09 29. September 2009 9
Where to Measure in Injection Molding? Part related (p,v,t) Machine related P far from the gate P near the gate P gate P in front of the screw P hydraulic frozen plastic plastic melt hydraulic oil dimensions, weight, shrinkage... Viscosity changes Injection work Machine Control Proplast 2009 / Srr 24 Sept 09 29. September 2009 10
Injection Molding Parameters and Quality 1: highest influence on part quality / 9: lowest influence on part quality Cycle Time Injection Speed Metering Time Melt Cushion Cavity Pressure Integral Maximum Cavity Pressure Melt Temperature Mold Temperature Fixed Half Mold Temperature Moving Half Technical Precision Parts: Connectors... (Thinwalled) Technical Parts: Gear Wheels... (Thickwalled) Optical Parts: Lenses, Brake Lights, Mirrors... Fast Cycle Precision Parts: One-Way Shavers... Medical Parts: One-Way Syringes, Pipettes... Technical Packing Material: Tape Cassettes, CD-Covers... Office Appliances: Rulers, Squares, Stencils... General Parts: Housings, Covers, Vacuum Cleaners... Unplasticised PVC Parts: Pipe Connections, Fittings... [Source Demag] Proplast 2009 / Srr 24 Sept 09 29. September 2009 11
The Cavity Pressure Curve Volume change due to cooling of melt; compensated by holding pressure Pressure Gate freezes Cavity is volumetrically filled (switch-over point) Time Start injection Melt reaches sensor Atmospheric pressure start of shrinkage Proplast 2009 / Srr 24 Sept 09 29. September 2009 12
Cavity Pressure and Quality Injection Compression Holding Surface, Forming of Weight, dimensions, warpage, shrinkage, blow holes, Quality warpage, cristallinity, orientation contour, flash formation, weight, sink marks, orientation inner layers outer layer dimensions Maximum pressure sealing point Switch-over Proplast 2009 / Srr 24 Sept 09 29. September 2009 13
Cavity Pressure For Three Important Processes Production Monitoring Measure pressure for complete cycle; then decide if part is Good or Bad Real-time Process Signals Immediate outputs to activate Alarms, Switch-over or open/close valve gates Process Control After cycle signals to optimize hot runner temperatures Proplast 2009 / Srr 24 Sept 09 29. September 2009 14
Production Monitoring with CoMo Injection System Process data Analysis Good / Bad signal Quality report Mould with sensors CPS (Cavity pressure) Data processing system Scrap separation Data storage statistics Proplast 2009 / Srr 24 Sept 09 29. September 2009 15
Production Monitoring Short Shot Problem Detection and Sorting of Short Shots Proplast 2009 / Srr 24 Sept 09 29. September 2009 16
Production Monitoring: Short Shot Monitoring Maximum Pressure Short Shot Good Part Proplast 2009 / Srr 24 Sept 09 29. September 2009 17
Production Monitoring Example Short Shot Proplast 2009 / Srr 24 Sept 09 29. September 2009 18
Realtime Process Control Process Data System Parameter Tool with Cavity Pressure Sensors Control system Set parameter During Cycle Proplast 2009 / Srr 24 Sept 09 29. September 2009 19
Real-Time Control: Examples Cascade control in sequential injection molding Open & close needle gates using a pressure threshold Fluid Injection Molding (GIT gas-assisted molding & WIT water-assisted) Open fluid valve using a pressure threshold Control Injection Compression / Embossing Molding Start compression phase with pressure threshold Proplast 2009 / Srr 24 Sept 09 29. September 2009 20
Real-Time Control: Switch-Over with Cavity Pressure Cavity volumetrically filled (switchover) Holding pressure used to compensate for shrinkage Gate freezes Pressure Threshold Injection starts Melt at Sensor Athospheric pressure reached; Shrinkage continues.. Note: In most applications the sensor position is not critical. Proplast 2009 / Srr 24 Sept 09 29. September 2009 21
Continuous Process Control Process Data System Parameter Tool with Cavity Pressure Sensors Control system Set parameter After Cycle Proplast 2009 / Srr 24 Sept 09 29. September 2009 22
Hot Runner Balancing Optimization of Tip Temperatures Proplast 2009 / Srr 24 Sept 09 29. September 2009 23
Hotrunner Control: Setting The Correct Temperatures 285 C Cavities/ Part 285 C 285 C 285 C Hot Runner Tips Cavity Pressure Sensors Proplast 2009 / Srr 24 Sept 09 29. September 2009 24
Optimization of Hot Runner Tip Temperatures Unbalanced Mold Balanced Mold Cavity Pres ssure Cavity Pres ssure Time Time Proplast 2009 / Srr 24 Sept 09 29. September 2009 25
Optimization of Hot Runner Tip Temperatures Unique filling pattern during injection and start of compression Unbalanced Mold Cavity Pres ssure Time Region of interest Proplast 2009 / Srr 24 Sept 09 29. September 2009 26
Balancing of Hot Runner Tip Temperatures Goal Simultaneous filling of all cavities Cavity Pressure Cavity Pressure Time Correlation of fill in each cavity No partial filling necessary All changes can be detected Cavity Pressure Time Proplast 2009 / Srr 24 Sept 09 29. September 2009 27
Optimizing Hot Runner Tip Temperatures Pressure rise too early Pressure rise too late Cavit ty Pressure Time Cavit ty Pressure Time Changes on the process Cavity pressure rises too early Cavity fills quicker Reduce nozzle temperature Cavity pressure rises too late Cavity fills slower Increase nozzle temperature Proplast 2009 / Srr 24 Sept 09 29. September 2009 28
Optimizing Hot Runner Tip Temperatures Unbalanced Mold Balanced Mold Proplast 2009 / Srr 24 Sept 09 29. September 2009 29
Hot Runner Balancing Optimization of Tip Temperatures Proplast 2009 / Srr 24 Sept 09 29. September 2009 30
Example: Balancing of Hot Runner Tip Temperature Automatic hot runner balancing using Kistler Multiflow Adjustment of hot runner nozzle temperatures using cavity pressure Mold / part: 16 Cavities 16 Cavity pressure sensors 8 Hot runner tips with 2 Cavities / Tip Material: PA 6 Part weight: Shot weight: 0,17 g 6,65 g Proplast 2009 / Srr 24 Sept 09 29. September 2009 31
Unbalanced Process Cavity Filling 1 2 3 4 5 6 7 t 8 Proplast 2009 / Srr 24 Sept 09 29. September 2009 32
Unbalanced Process Cavity Filling 1 2 3 4 5 6 7 t 8 Proplast 2009 / Srr 24 Sept 09 29. September 2009 33
Unbalanced Process Cavity Filling 1 2 3 4 5 6 7 t 8 Proplast 2009 / Srr 24 Sept 09 29. September 2009 34
Unbalanced Process Cavity Filling 1 2 3 4 5 6 7 t 8 Proplast 2009 / Srr 24 Sept 09 29. September 2009 35
Unbalanced Process Cavity Filling 1 2 3 4 5 6 7 t 8 Proplast 2009 / Srr 24 Sept 09 29. September 2009 36
Unbalanced Process Cavity Filling 1 2 3 4 5 6 7 t 8 Proplast 2009 / Srr 24 Sept 09 29. September 2009 37
Balanced Process with Multiflow Cavity Filling 1 2 3 4 5 6 7 8 Proplast 2009 / Srr 24 Sept 09 29. September 2009 38
Balanced Process with Multiflow Cavity Filling 1 2 3 4 5 6 7 8 Proplast 2009 / Srr 24 Sept 09 29. September 2009 39
Balanced Process with Multiflow Cavity Filling 1 2 3 4 5 6 7 8 Proplast 2009 / Srr 24 Sept 09 29. September 2009 40
Without Multiflow T i =const=285 C; t = 140,2 ms Correlation Level: 300bar t Proplast 2009 / Srr 24 Sept 09 29. September 2009 41
Balancing with Multiflow: Overview Cycle 1 Cycle 5 Cycle 15 Cycle 25 Cycle 40 Cycle 55 Proplast 2009 / Srr 24 Sept 09 29. September 2009 42
Balanced with Multiflow t = 8,4 ms Correlation Level: 300bar t Proplast 2009 / Srr 24 Sept 09 29. September 2009 43
Results: Different Balancing Methods Method Time / Cycles needed t [s] Manual Balancing without Cavity Pressure Manual Balancing using Cavity Pressure Curve ½ Day 0,126 60 Cycles 0,069 Automatic Balancing with Multiflow 20 Cycles 50 Cycles 0,0431 0,0019 Proplast 2009 / Srr 24 Sept 09 29. September 2009 44
Long Time Measurement: No Control vs. MultiFlow Method 0.140 0.120 Manuell Multiflow Difference Time [s] 0.100 0.080 0.060 0.040 0.020 0.000 No control Kistler Multiflow 1 400 1200 2000 Cycle Proplast 2009 / Srr 24 Sept 09 29. September 2009 45
Results: Long Run Without Multiflow: 30% Change in Filling Time Difference With Multiflow: Reduced Fill Time Difference Constant Fill Time Difference over 2500 Cycles Proplast 2009 / Srr 24 Sept 09 29. September 2009 46
Summary Cavity pressure is the most important aspect of the molding process, ensuring: 100% Quality control Zero-Defect molding Automatically balancing of hot runner tools based on cavity pressure measurements stabilizes production processes and quality and reduces setup times Proplast 2009 / Srr 24 Sept 09 29. September 2009 47
Thank You Very Much For Your Attention! Proplast 2009 / Srr 24 Sept 09 29. September 2009 48