Injection

1
Injection Extrusion Molding of Polymers

• Lili Esfahani, Kevin Griffin, Wes Lambert,
• Michelle McChesney, Andy Peterman, Nevin Smith,
  and Frank Yang
• for MatE 186 Polymers Lab
• Dr. Richard Chung

2
Overview

• Polymers Used
• Processing Variables
• Injection
• Process
• Variables
• Results
• Extrusion
• Process
• Variables
• Results
• Conclusion

3
Processing Variables

• Variables in material properties
• TgltTmltTw
• Viscosity
• Variables in injection process
• Temperature
• Pressure

4
Polymers Used
5
Injection
Extrusion schematic (Morton-Jones p.76)
6
Injection Process

• Preheat barrel
• Load hopper
• Clamp mold into place
• Depress and hold injector knob
• Allow mold to cool
• Remove the molded part

7
Injection Variables

• Temperature
• Pressure
• Injection time
• Clamped time

8
Injection Results

• Successes
• Polycarbonate T232C P85PSI
• ABS T1190C T2232C
• Failure
• Nylon T232C P85PSI

9
Injection Results
10
Extrusion
Extrusion schematic (Morton-Jones p.76)
11
Extrusion Process

• Preheat the barrel and die
• Add polymer beads
• Turn on screw
• Guide parison into the bath
• Razor knife flash removal

12
Extrusion Variables

• Material
• Temperature
• Rotational rate
• Cooling

13
Extrusion Results

• Successes
• LDPE
• thermoplastic rubber
• Failure
• HDPE

14
Extrusion Results
15
Conclusion

• Injection
• Advantages
• High production rates
• Repeatability within tolerances
• Little to no finishing of parts
• Disadvantages
• High initial equipment investment
• Part must be designed for effective molding

16
Conclusion

• Extrusion
• Advantages
• Relatively low labor
• Mixing can be done at the process level
• Disadvantages
• Swell of polymer after die
• Limited symmetry of parts