bubbles

[Mic]

I have tried the molds with the wing nuts tighter and looser, and with Irwin clamps, heating the mold, cold mold, holding pressure for 5,10, 15 and 20 counts, opened as soon as possible, with another plastic per bt and still no good.  I am sending them back.  been in contact with bt and they are good to work with. 

[BareKnuckleJigs]

X2 with TTDuckman.  Don't pour plastic into Your injector.  Suck/draw the plastic into Your injector...with the injector.  Put the tip of the injector in the plastic and draw with the plunger handle...shoot the mold...hold pressure for 10+ seconds, then top off the sprue with a little shot of plastic...and yes, shoot slow.

[TTDuckman]

mic,

Are you pouring the plastic into the injector?  Please don't this as an arguement, I am only trying to help.  If your plastic is getting to a proper temperature and you are sucking up the plastic and shooting it into the mold.  It should work.

I know people have different ideas on this, but here is my take on any injection mold (except tube molds) I have ever used.  The only thing that should ever be heated is the injector and that is merely for the first injection in your run (to make sure that the plastic doesn't cool prematurely in the injector).  After the first injection, the injector is plenty warm.  I live in northern IL and my molds are always cold in the winter on the first shot (20-50), sometimes colder.  Injection molds in my mind don't need to be heated.  In production, the biggest problem with productivity is mold heat.  The cooler I can keep molds the better.



Tim

[412BaitCo]

In my experience working in my basement a cold mold no matter what the plastic temp with baits that use a lot of plastic or have a lot of appendages will create a shock when the hot plastic hits it. This makes the plastic cure way faster then it should. This does two things one it stops the plastic in the topped off sprue from being sucked down long enough and in turn creates the plastic voids you speak of. Now to clarify what I see as heating a mold. I don't go as far as to put them on the griddle. I don't think they need to be that hot in most circumstance they just can't be ice cubes. I actually have one of those oil filed radiator space heaters that I use to warm my shop a little and I just set the molds I plan to use on top of that for a little to take the chill off and it seems to work well for me. I found this process to be extremely helpful in the 4.5" swim shads and regular diameter carrots which both have a tendency to dent. I have a feeling it will help with your mold as well. Good luck and I hope this helps.

Don