Importance of Drying > Fabrication Process > Purging & Using Regrinds > Finishing



- Injection Molding

  Most common injection molding machines can be used to process CALIBRE* polycarbonate resins. The volume of plastic required to fill the mold cavity will determine the size of the injection molding machine to be used.
It is a good practice to deep the shot size of the machine between 20 percent and 75 percent of the total capacity, and an optimum shot size is between 40 and 60 percent.
The screw should have a minimum of 15:1 length-to-diameter (L/D) ratio, ideally 20:1, and a compression ratio between 1.5:1 and 3.0:1

  Fill pressure should be set as high as is practical to fill the mold as rapidly as possible thereby reducing molded-in stress.
The holding pressure and holding time should, however, be as low as possible. The injection machine should be run at low injection speed at the initial stage, increasing to high speed at later stages of the process.
Injection speeds are also determined by the gate design. If the gate is too small, resins are susceptible to the formation of gate blush due to the high injection speed.

  A moderate screw rotation speed of 40 to 70 rpm is recommended for fabrication. Machine back pressure should be set as low as is practical to facilitate venting.
When color pigment or concentrate is used, back pressure can plasticate the resin and produce a uniform polymer melt, resulting in a more consistent part.
The setting of barrel and mold temperatures are determined by the melt flow rates (MFR) of CALIBRE resins, as indicated in Table 1.

Table 1: Suggested Injection Molding Temperatures(กษ)
MFR 5 8 10 15 22 30
Feed zone 270 - 290 265 - 285 260 - 275 255 - 270 250 - 265 245 - 260
Rear zone 280 - 300 275 - 290 270 - 285 265 - 280 260 - 270 255 - 265
Middle zone 290 - 320 285 - 310 280 - 295 275 - 290 270 - 280 265 - 275
Front zone 290 - 320 285 - 310 280 - 295 275 - 290 270 - 280 265 - 275
Nozzle 285 - 315 280 - 305 275 - 290 270 - 285 265 - 275 260 - 270
Melt 300 - 330 395 - 320 290 - 305 285 - 300 280 - 295 275 - 285
Mold 80 - 110 75 - 105 70 - 100 65 - 95 60 - 95 60 - 95


- Extrusion/Blow Molding

  CALIBRE polycarbonate resins are thermoplastic materials. In addition to injection molding, they can also be extruded or blow molded. Extrusion is mainly for production of sheets and films. Blow molding, including injection blow molding and extrusion blow molding, is for the production of medium-to large-sized hollow bottles, barrels and other containers. See Tables 2,3 and 4 for detailed fabrication conditions.


Table 2: Suggested Extrusion Temperatures(กษ)
PARAMETERS SUGGESTED TEMPERATURE(กษ)
 Extrusion machine
  - Feed zone
  - Compression zone
  - First metering zone
  - Vent/Compression zone
  - Second metering zone
290 - 300
285 - 295
270 - 290
260 - 280
270 - 290
 Adapter 280 - 285
 Die 260 - 295
 Chill roll (Solid sheet extrusion) 120 - 150
 Anneal chamber
 (Multi-wall sheet extrusion)		 60 - 80


Table 3: Suggested Injection Blow Molding Conditions
PARAMETERS SUGGESTED RANGE
 Extrusion machine
 temperature setting(กษ)
  - Feed zone
  - Compression zone
  - Metering zone
  - Accumulator head
  - Die

250 - 265
245 - 260
240 - 255
230 - 260
230 - 260
 Mold temperature(กษ)
  - Bottom
  - Body
  - Neck
60 - 80
60 - 80
50 - 65
 Screw speed(RPM) 10 - 80
 Supporting air pressure(Bar) 0.5 - 1
 Blowing pressure(Bar) 5 - 10
 Blowing time(s) 25 - 25
 Cycle time(s) 35 - 60


Table 4: Suggested Extrusion Blow Molding Conditions
PARAMETERS SUGGESTED RANGE
 Barrel temperature(กษ)
  - Feed zone
  - Middle zone
  - Front zone
  - Nozzle
270 - 280
280 - 295
280 - 295
280 - 295
 Heating sprue
 Temperature(กษ)
  - Sprue
  - Gate

295 - 300
290 - 295
 Air pressure(Kg/cm2)
  - First stage
  - Second stage
0.8 - 2
8 - 10
 Die temperature when blowing(กษ) 60 - 80


"*" Trademark of the Dow Chemical Company, licensed for use by LG DOW Polycarbonate LTD.