CAUTION!
Mechanical hazard – risk of damage to the hot runner. In the event of water leaking into the
hot runner, the nozzle heaters could fail. Make sure all water is removed before starting up
the hot runner.
5. Using compressed air, remove any water around the nozzle tips and parting lines.
6. Make sure all safety latches have been removed from the mold and hot runner.
7. Remove all locks and tags.
CAUTION!
Mechanical Hazard – Risk of damage to hot runner. Dry cycling the valve stems on a hot
runner system is not recommended. Dry cycling can damage the valve stems, nozzle tips,
and gate steel. If dry cycling is required for inspection of the hot runner, this should be kept
to a minimum. If a long dry cycle of the injection molding machine is required, then it is not
recommended to actuate valve stems during this operation.
5.2 Heating Up the Hot Runner, Mold and Machine
To bring the hot runner, mold and machine up to operating temperature, do the following:
1. If equipped, make sure the dryer is enabled and adjusted to the proper operating
temperature.
2. Make sure the water chiller is enabled and adjusted to the proper operating temperature.
3. If equipped, make sure the mold enclosure de-humidier, air compressor and water tower
supplies are enabled.
4. Check the air pressure settings for the machine.
5. Make sure the compressed air for the mold is turned o. If the compressed air is left on as the
hot runner heats up, air will leak from the system. This will cool the hot runner and delay the
startup.
6. Slowly open the clamp to full shutheight.
7. Turn on the hot runner cooling system.
WARNING!
Hot resin spray hazard – risk of death or serious injury. Overheated resin can generate
pressurized gas that when suddenly released can cause material to spray out. Do not allow
resin to overheat. If the startup process is interrupted, turn o all barrel heaters and retract
the injection unit to allow the hot runner to vent between the machine nozzle and the
sprue bushing. For extended delays, follow the machine manufacturer’s and resin supplier’s
procedures for machine shutdown.
8. Turn on the machine barrel heaters and allow them approximately 1/2 to 1 1/2 hours to
reach operating temperature, depending on the size of the injection unit.
v 2.2 — March 2021 Unify Manifold System
56 Heating Up the Hot Runner, Mold and Machine
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