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28.  Hot runner is an extension of the injection unit.  They keep the plastic at a liquid (molten) state up into the mold cavity.

20.  If you vented 30% of the perimeter of the plastic injection mold and are still have burns on your plastic part, you could vent the ejector pins for additional vents (good thing about venting ejector pin, they are self cleaning).    

11.   What fluid is used for cooling passages in plastic injection mold to control temperature. 

29.  The biggest advantage of a Hot Runner Mold is waste free (no runner).

Bonus 1   Why do they surface grain or etch a plastic injection mold, what is the purpose?

7.  Date grids or codes are important on a plastic part that is used in a car, in case of a recall, they can isolate suspect parts.

19.  The correct vent depths for the following plastics recommended by material supplier     – ABS   .001-.0015″     – PP    .0005-.0012″     – Glass Filled Nylon  .001-.0025″

33.  Temperature on a hot runner system in a plastic injection mold, each zone is controlled by an individual heater and temperature is controlled by a thermocouple.

5.  It is important to have the cavity number on a multi cavity plastic injection mold, so you can troubleshoot problems or issues.

1.  Making a plastic part is similar to what operation that we discussed in the PP during week 1?