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PET (Polyethylene Terepthalate)

Also Known As

  • Arnite A
  • Caripak P
  • Eastapak
  • Impet
  • Rynite

Typical Machine Settings: Subject To Polymer Grade

Nozzle

Front

Centre

Rear

Barrel Temperature

280 - 300oC

265 - 295oC

260 - 295oC

260 - 290oC

Melt Temperature

285 - 300oC

Must be measured with a pyrometer by taking an airshot through the injection machine nozzle.

Hot Runner Temperature

285 - 300oC

Mould Temperature

90 - 120oC

Run at upper end of range for best surface finish.

Injection Rate

Medium To Fast

Specific Injection Pressure

350 - 1400 Bar (5,000 - 20,000psi)

Screw Back Pressure

3.5 Bar (50psi)

Screw Speed

Slow

Processing Features

Structure

Semi-Crystalline

Specific Gravity

1.35

Viscosity

Medium

Needs large runners and thick wall sections.

Shear Rate Susceptibility

Medium

Needs large gates.

Temperature Window

Narrow

Needs accurate & stable control

Residence Time

Short

Aim for '1-Shot' residence time

Start-Up Precedure
  • Ensure all heaters are thoroughly baked dry - do not rely on brief ‘soft start’ systems to do this.
  • Fast Heat controllers automatically and safely bakeout wet heaters - ask for details.
  • Turn on water lines to stabilise tool and manifold temperatures.
  • Turn on manifold control zone(s) and allow to warm up until measured value is within 10oC of setpoint.
  • Now turn on tip zones and allow to settle at setpoint for 5 - 10 minutes before starting production.
  • Take an airshot from the machine barrel and check that the melt temperature is correct.
  • Start moulding parts on a semi-automatic cycle until suitable machine settings are established.
  • Avoid lengthy delays between cycles during this setting procedure.
  • Switch to automatic cycle when parts are being produced, and fine tune the machine settings

Shut-Down Precedure
  • DO NOT shut down with PET in the machine barrel of hot runner system.
  • Purge the barrel thoroughly with Acrylic or other recommend polymer.
  • Now start moulding parts in the purging material until all drops are clear of PET.
  • DO NOT attempt to purge through an open mould, or melt leakage my result.
  • Shut down the machine & mould when ALL of the PET has been cleaned out.