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Injection Molding-Injection MoldingProcess Description
ver. 1
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Overview
• Equipment• Process
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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EquipmentEquipment
Cl M ld B lClamp MoldHopper
Barrel
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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EquipmentEquipment
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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KrausMaffei at Ford 4000 tonnesKrausMaffei at Ford - 4000 tonnes
5ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009
Machine schematic
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Mold
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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MoldMold
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Modular moldsModular molds
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Mold schematic
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Moldspruerunner
cavitygate
sprue nozzlep
sidefront ejectionpin
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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pin
Process
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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ProcessProcess
• Pellets placed in hopperPellets placed in hopper• Pellets fall into barrel through throat
P ll t k d t f lid b d• Pellets packed to form solid bed– air forced out through hopper
• Pellets melted by mechanical shear between barrel and screw
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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ProcessProcess
• Melted plastic forms shot in front of• Melted plastic forms shot in front of screw
b k l ti– screw moves back as plastic moves forward (reciprocating screw)
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Process
• Screw moves forward to inject plastic j pinto mold cavity
P t l d lidifi• Part cools and solidifies– next shot is made
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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ProcessProcess
• Mold opens• Mold opens• Ejection pins move forward to eject part
• Mold closes• Process starts again• Process starts again
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Solid bedSolid bed
• Pellets crushed together• Pellets crushed together• Air ejected
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Melting zoneMelting zone
• Solid bed melted by mechanical shear• Solid bed melted by mechanical shear
barrelbarrel
screw flightsolid bed
secondarymixing flow
screw flight
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Homogenization zoneHomogenization zone
• Melted polymer is homogenized thermally and color-wise.y
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Injection pressureInjection pressure
• Typically 15,000 psi• Ranges from 3 000 to 40 000 psiRanges from 3,000 to 40,000 psi• Hydraulic pressure is about 10x less
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Process timeClose mold
InjectionOpen and eject
part jp1
533
35
Part cooling
Pack and hold
15
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Pressure historyy
Mold closed time
Cycle time
50
ject
ionCooling
Mold closed time
2 st c
losi
ng
Inje
ctio
n
Pack
ze o
ff Par
t ej
25 Fas
Gat
e fre
ez
33 3515500
Time (s)
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Time (s)
Temperature historyTemperature historyCooling
200
ject
ion
part
100
st c
losi
ng
njec
tion
Pack
ze o
ff Par
t ejp
gate
Fas I
Gat
e fre
ez
33 3515500
Time (s)
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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Time (s)
Gates and freeze offGates and freeze-off
Filling &Packing
Cooling
ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009
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