Husky Unify - High Pressure Hazards

• Molten Material
Never touch process material purged or otherwise owing from the nozzle, mold, hot runner or
feed throat area. Molten material can appear cool on the surface, but remain very hot on the inside.
Wear personal protective equipment when handling purged material.
2.3.3 High Pressure Hazards
WARNING!
Burn and hot resin spray hazard – risk of death, serious injury and/or damage to the hot
runner. All nozzle and sprue heaters (if equipped) must be turned on when manifold
heaters are turned on. Failure to do so could result in generation of dangerous pressure
levels in the manifold, resulting in component failure and/or sudden release of hot resin.
Pressure inside the hot runner manifold(s) can increase to dangerous levels if the nozzle and
sprue heaters (if equipped) are not turned on before or at the same time as the nozzle sprue.
The pressure is generated when the injection nozzle sprue is plugged with frozen resin and the
residual resin in the manifold is heated. This pressure can release suddenly causing the resin plug
to eject from the sprue and hot resin to spray from the nozzle tips. The risk of serious burn injuries
as a result is increased.
Moisture that inltrates and is trapped in the hot runner molten material can also increase the
risks of this potential hazard. If the temperature of the water in the molten material becomes
greater than 400 °C (725 °F) , the pressure of this trapped water can be signicant enough to
rupture the metal housing and cause serious injury to personnel.
To avoid this hazard, do the following:
1. Always make sure all nozzle and sprue heaters (if equipped) are turned on any time manifold
heaters are turned on outside of the mold. The nozzle and sprue heaters can be turned on
independently of the manifold heaters, however, it is recommended that they be heated rst
or slaved to the manifold heaters so they heat up in unison.
2. Always make sure the nozzle tips are open and the nozzle housings are dry prior to applying
heat to the manifold.
IMPORTANT!
In the event of water leaking onto or into the hot runner, the nozzle tips must be removed (cold)
and the plastic in the nozzles drilled out to ensure they are open to atmosphere. This can be done
using a standard twist drill with the cutting edges removed to prevent damage to the melt
channel.
Replace the cavity plate prior to heating the system.
Hot Runner Installation Manual v 2.2 — March 2021 Safety Summary
Safety Hazards 19