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PBT Polyester (Polybutylene Terepthalate)

Also Known As

  • Arnite T
  • Celanex
  • Crastin
  • Orgater
  • Pocan
  • Ultradur
  • Valox

Typical Machine Settings: Subject To Polymer Grade

Nozzle

Front

Centre

Rear

Barrel Temperature

245 - 265oC

240 - 265oC

235 - 255oC

230 - 250oC

Melt Temperature

245 - 270oC

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

Hot Runner Temperature

250 - 270oC

Mould Temperature

55 - 110oC

Run at upper end of range for best surface finish.

Injection Rate

Medium To Fast

Specific Injection Pressure

700 - 1400 Bar (10,000 - 20,000psi)

Screw Back Pressure

2.0 - 3.5 Bar (30 - 50psi)

Screw Speed

45 - 75 rpm

Processing Features

Structure

Semi-Crystalline

Specific Gravity

1.35

Viscosity

High

Needs large runners & thick wall sections.

Shear Rate Susceptibility

High

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