1. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
Improving Processing of Rubber in Injection, Transfer and Compression Molding Process
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

2. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
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.
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

3. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
Molding Process
Mold heating generally accounts for more than two thirds of total cycle time
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

4. Benefits of Optimum Heating Process
Temperature Uniformity
Reduced Residual Part Stress
Cycle Time Reduction
Scrap Rate Reduction
Energy Savings
Reduced Maintenance
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

5. Factors Affecting Mold Heating
Material Thermal properties
Part Geometry
Thermal breaks between plates or inserts
Location of Thermocouple
RUBBER PART
Thermal properties
Part Thickness
Geometry
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

6. Thermal Conductivity of Materials
Thermal Conductivity (W/m K) at 20 C
Factor
ISOBAR
390 – 15,000
****
Copper
390 1x
Aluminum
237
1.6x
Beryllium Copper
105
3.7x
Steel
20 – 40
13x
Water
0.60
650x
Plastics
0.15 – 0.30
2,400x
RUBBER
0.13 – 0.16
2,600x
Air
0.025
15,600x
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

7. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
Types of Isobars
STANDARD
FINNED
STEPPED
HOLLOW
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

8. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
Isobar - Function
HEAT IN
METAL WICK
HEAT OUT
LIQUID FLOW
VAPOUR FLOW
ISOBAR SHELL
HEAT IN
HEAT OUT
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

9. 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
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

10. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
Isobars
Passive Device
Superthermal Conductors
Thermal Uniformity of +/- 1 °C
Orientation Dependent
Operating Temperature 0 – 280 °C
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

11. Thermal Performance of 25mm Diameter x 150mm Long Core
WITH ISOBAR
CORE
SOLID
MOLDED PART
CORE PIN
ISOBAR
HEATED
MOLD
PLATE
HEATER
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

12. Thermal Performance of 25mm Diameter x 150mm Long Core
Steady State
Steady State
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

13. Thermal Performance of 25mm Diameter x 150mm Long Core
Core Base
Core Top
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

14. Examples of Cores with Isobars
CORE PIN
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

15. Isobar Design in Heated Cores
TEMPERATURE UNIFORMITY OF
HEATED CORE
No Isobars
With 4 Isobars
Indirect Heating of Isobars
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

16. Isobar Design in Heated Cores
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

17. Isobar Design in Transfer Molding Tree Bar Mold
Core Pin
Isobar
Heater
Tree Bar
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

18. Isobar Design in Heated Cores
Epoxy
Plug
ISOBAR
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

19. Rubber Molding over Flat Plates
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

20. Acrolab Ltd. – Copyright 2003 – Introduction to Mold Cooling & Heating
ISOPLATEN
Bi-Level Matrix of Heaters and Isobars
Acrolab Ltd. – Copyright 2003 – Introduction to Mold Cooling & Heating

21. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
STANDARD PLATEN
24” x 24” x 3”
With 5 heaters
Heaters ON
Thermocouples
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

22. STANDARD PLATEN 24” x 24” x 3” With 5 heaters One Heater disconnected
Heater OFF
Thermocouples
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

23. HEATER TEMPERATURE PROFILE VS LENGTH
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

24. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
ISOPLATEN
24” x 24” x 3”
With 5 Heaters
and 13 Isobars
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

25. One heater disconnected
ISOPLATEN
24” x 24” x 3”
With 5 Heaters
und 13 Isobars
One heater disconnected
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

26. Acrolab Ltd. – Copyright 2003 – Introduction to Mold Cooling & Heating
Standard Platen
Isoplaten
Acrolab Ltd. – Copyright 2003 – Introduction to Mold Cooling & Heating

27. Isoplaten vs Platen Consideration
Thermal uniformity dynamic +/- 2 °C vs static +/- 17 °C
Single Zone vs Multiple Zone Control
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

28. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
ISOPLATEN
Mounting Holes
Isobar
Heater
Thermocouple
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

29. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
ISOPLATEN
T - Slots
Isobar
Heater
Thermocouple
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

30. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
ISOPLATEN
Center Hole
Isobar
Heater
Thermocouple
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber

31. Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber
ISOPLATEN
Thermocouple
Thermoswitch
Isobar
Heater
Acrolab Ltd. – Copyright 2003 – Improving Processing of Rubber