Improving Processing of Rubber in Injection, Transfer and Compression Molding Process Acrolab Ltd. Windsor Ontario Canada 519-944-6900 eryzer@acrolab.com www.acrolab.com 1
Introduction Mold heating time is the biggest contributor to the overall cycle time in almost all rubber molding applications Many molders fail to claim additional savings that can be achieved through optimized heating process 2
Molding Process Mold heating generally accounts for more than two thirds of total cycle time Open & Eject 6% Close 3% Fill 11% Heating 51% Pack & Hold 29% 3
Benefits of Optimum Heating Process Temperature Uniformity Reduced Residual Part Stress Cycle Time Reduction Scrap Rate Reduction Energy Savings Reduced Maintenance 4
Factors Affecting Mold Heating MOLD Material Thermal properties Part Geometry Thermal breaks between plates or inserts Location of Thermocouple Thermal properties Part Thickness Geometry RUBBER PART 5
Thermal Conductivity of Materials ISOBAR Steel Water Plastics RUBBER Air Material Aluminum Beryllium Copper Thermal Conductivity (W/m K) at 20 C 390 15,000 237 105 20 40 0.60 0.15 0.30 0.13 0.16 0.025 Factor **** 1.6x 3.7x 13x 650x 2,400x 2,600x 15,600x 6
Types of Isobars STANDARD FINNED STEPPED HOLLOW 7
Isobar - Function HEAT IN METAL WICK LIQUID FLOW HEAT OUT VAPOUR FLOW HEAT IN ISOBAR SHELL HEAT OUT 8
Isobar Function and Orientation VERTICAL HORIZONTAL / INCLINED HEAT OUT HEAT IN HEAT OUT HEAT IN HEAT INPUT MUST BE BELOW HEAT OUTPUT HEAT INPUT AND OUTPUT CAN BE ANYWHERE ALONG THE ISOBAR LENGTH 9
Isobars Passive Device Superthermal Conductors Thermal Uniformity of +/- 1 C Orientation Dependent Operating Temperature 0 280 C 10
Thermal Performance of 25mm Diameter x 150mm Long Core CORE WITH ISOBAR CORE SOLID MOLDED PART CORE PIN ISOBAR HEATED MOLD PLATE HEATER 11
Thermal Performance of 25mm Diameter x 150mm Long Core 200 175 Temperature (C) 150 125 100 75 Steady State Steady State With Isobars Without Isobars 50 25 0 5 10 15 20 25 30 35 40 Time (Minutes) 12
Thermal Performance of 25mm Diameter x 150mm Long Core 225 200 Core Base Temperature (C) 175 150 Core Top With Isobars Without Isobars 125 100 0 2.5 5 7.5 10 12.5 15 Length (Cm) 13
Examples of Cores with Isobars ISOBAR CORE PIN 14
Isobar Design in Heated Cores TEMPERATURE UNIFORMITY OF HEATED CORE No Isobars With 4 Isobars Indirect Heating of Isobars 15
Isobar Design in Heated Cores ISOBAR 91.4 mm 16
Isobar Design in Transfer Molding Tree Bar Mold Core Pin Isobar Tree Bar Heater 17
Isobar Design in Heated Cores Epoxy Plug ISOBAR 18
Rubber Molding over Flat Plates 19
ISOPLATEN Bi-Level Matrix of Heaters and Isobars Acrolab Ltd. Copyright 2003 Introduction to Mold Cooling & Heating 20
STANDARD PLATEN 24 x 24 x 3 With 5 heaters Heaters ON Thermocouples 21
STANDARD PLATEN 24 x 24 x 3 With 5 heaters One Heater disconnected Heaters ON Heater OFF Thermocouples 22
HEATER TEMPERATURE PROFILE VS LENGTH 23
ISOPLATEN 24 x 24 x 3 With 5 Heaters With 13 Isobars 24
ISOPLATEN 24 x 24 x 3 With 5 Heaters With 13 Isobars One heater disconnected 25
Standard Platen Isoplaten Acrolab Ltd. Copyright 2003 Introduction to Mold Cooling & Heating 26
Isoplaten vs. Standard Platen Frequency 140 120 100 80 60 40 20 0 ISOPLATEN Frequency Frequency 120 100 80 60 40 20 0 ISOPLATEN 1 Heater Disconnected Frequency 296 298 300 302 304 306 308 310 312 Temperature ( F) 314 316 292 295 298 301 304 307 310 Temperature (F) 313 316 Frequency 70 60 50 40 30 20 10 0 STANDARD PLATEN Frequency Frequency 25 20 15 10 5 0 STANDARD PLATEN 1 Heater Disconnected Frequency 290 293 296 299 302 305 308 311 314 317 320 259 267 275 283 291 299 307 315 323 331 339 347 355 Temperature (F) Temperature (F) Acrolab Ltd. Copyright 2003 Introduction to Mold Cooling & Heating 27
Isoplaten vs Platen Consideration Thermal uniformity +/-2 C vs +/- 15 C Single Zone vs Multiple Zone Control 28
ISOPLATEN Mounting Holes Isobar Heater Thermocouple 29
ISOPLATEN T - Slots Isobar Heater Thermocouple 30
ISOPLATEN Center Hole Isobar Heater Thermocouple 31
ISOPLATEN Thermocouple Thermoswitch Isobar Heater 32
Rubber Molding of Automotive Gaskets EXAMPLE#1 33
Bottom Plate Isobar Heater 34
Top Plate with Isobars in Inserts Isobar Heater 35
Rubber Molding of Automotive Gaskets EXAMPLE#2 36
Top Cavity Plate Isobar Heater 37
Middle Cavity Plate Isobar Heater 38
Bottom Cavity Plate Isobar Heater 39
Rubber Molding of Automotive Seals Example#3 40
49 Cavity Injection Mold Isobar 41
Rubber Molding Tool Example#4 42
Single Cavity Tool Ø25mm X 7.5" LG. ISOBARS- 12 PCS STANDARD Ø25mm X 6.5" LG. ISOBARS- 15 PCS REVERSE 43
Thermoset Molding of Automotive Head Lamp Reflectors 44
2 Cavity Thermoset Head Lamp Reflector Mold Heater Isobar Thermocouple 45
2 Cavity Thermoset Head Lamp Reflector Mold Heater Isobar 46
Isobar Design in Head Lamp Molds Isobars shown Prior to Install Optic Surfaces Electrical Box Shown with heater Leads and T/C Mold Insulated 47
Isobar Design in Head Lamp Molds Cooling Isobars Heaters Heat Generation In mold Inserts 48
Isobar Design in Head Lamp Molds Heating Zone Electrical Box Heat Generation In mold Shoe 49
Isobar Design in Head Lamp Molds Heat Generation In mold Shoe With Isobars in Slides Slide with Isobars 50