Cause: Melt temperature too low, injection pressure too low, gate too small, nozzle too small, mold too cold, exit from machine nozzle too small, nozzle blocked.

Remedy: Raise nozzle and manifold temperature, raise injection pressure, enlarge gate, raise mold temperature, fit larger nozzle, enlarge hole in machine nozzle, clear blockage.

Cause: Insufficient suck back, Melt temperature too high, gate too big, insufficient gate cooling, incorrect Nozzle type selected.

Remedy: Increase suck back, lower nozzle and/or mold temperature, reduce gate diameter, increase gate cooling, contact your Nozzle supplier for correct nozzle selection.

Cause: Heater failure, Thermocouple failure, Nozzle blockage, Incorrect allowance for expansion of nozzle.

Remedy: Check/replace heater, check/replace thermocouple, remove clean nozzle, re-machine nozzle cavity.

Cause: Incorrect colour change procedure, wrong type of nozzle.

Remedy: See guide for correct colour change below, Contact your supplier for correct nozzle selection.

Cause: Too high an injection pressure, temperature too high, poor shut off face flatness. Insufficient clamp pressure on molding machine, tool plates flexing.

Remedy: reduce injection/pack, lower nozzle/manifold/mold temp, increase machine clamp force, change tool.

Cause: Not enough venting in tool, injection speed too high, gate profile incorrect, material not dry.

Remedy: Add more venting, lower injection speed, increase “J” dimension on gate profile, dry material.

Cause: Tip material too soft for application.

Remedy: Change to Carbide tips, such as MASTIP.

Cause: Gate too large, incorrect nozzle selection, gate profile machined incorrectly.

Remedy: Fit bush/sprue nut to reduce gate, Contact hot runner system supplier for correct nozzle selection, check gate
machining profile.

Cause: Melt too cold, gate too small for material being used, excessive cooling around gate, too much contact between nozzle and mold, gate profile incorrect or incorrect type.

Remedy: Raise nozzle temperature, raise mold temperature around gate, check machining of nozzle cavity and make sure contact is at a minimum, check machining of gate profile and change if needed.

Cause: Incorrect nozzle type

Remedy: Change nozzle type

Cause: Mold too cold, melt too cold, cold slug in part.

Remedy: Raise mold temperature, raise melt temperature, use MOT nozzle.

Cause: Wrong nozzle selection, head of the nozzle too cold.

Remedy: Contact your hot runner suppier or nozzle supplier for correct nozzle selection, machine cold slug trap opposite gate, ensure contact area on nozzle head is minimum.

Cause: Too much head loss through nozzle head.

Remedy: Reduce head contact to a minimum, Sit head in thermally insulated material.

Cause: Not enough contact between nut and mold to dissipate heat.

Remedy: Change nut type with increased contact area to dissipate heat from nut.