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PVC-U (PVC Without Plasticiser - Rigid PVC)

Typical Machine Settings: Subject To Polymer Grade

Nozzle

Front

Centre

Rear

Barrel Temperature

175 - 195oC

170 - 190oC

160 - 180oC

150 - 170oC

Melt Temperature

175 - 195oC

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

Hot Runner Temperature

180 - 195oC

Mould Temperature

20 - 40oC

Injection Rate

Slow

Specific Injection Pressure

700 - 1250 Bar (10,000 - 18,000psi)

Screw Back Pressure

3.5 - 7.0Bar (50 - 100psi)

Screw Speed

40 - 50 rpm

Processing Features

Structure

Amorphous

Specific Gravity

1.45

Viscosity

High

Large runners must be used.

Shear Rate Susceptibility

High

Large gates must be used.

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