Howdy Barry, Guys,
You are 100% correct Barry, I work at a plant that uses Van Dorn Injection molding machines to produce insulators for transformers. If a part is pulled from the mold or ejected too soon (before it has time for the cooling jackets around the mold to cool it) you get a warped or mishapen part.
These are the same type machines that are used for plastic models, the "hold" time can be set on these machines to allow the part to cool thoroughly, most often it is the operator striving to meet a production goal by reducing the "hold" time.
Heat sinks are another form of distortion of styrene plastic, these are due to "cold" spots in the mold and generally causes depressed area in the part or causes the material to "freeze" or solidify before filling out the cavity in the mold.
Scorching is another problem, there are heaters inserted into the mold, they glow cherry red, (to give you some idea how hot they are), and a single heater becoming hotter than the others can cause scorched areas on the plastic.
I recently became the maintenance and machine shop superintendant where I work, so I get to hear about everyones problems with the machines and processes. I am off work now due to a neck injury, but I can only imagine the pile of work orders on my desk concerning the items mentioned in this topic.
One other thing, Barry was correct about the QC in alot of plants, mine is no different, the company seems to think more is better.
anyway, Barry just kinda sent me off on a rant, I had almost forgotten all about work....................thanks barry
lol j/j
Have a good day,
Greg aka GW