Pitting

[tboxfish]

One of my wife's molds has started having issues with the body pitting. She has used different manufactures plastic, still the same issue. She has 3 different crappie molds and only the Slab Bug has developed this issue. She shoots all them at the same time. Has tried heating the mold up more, as she had turned the mold heat down to eliminate some flashing issues she was having. Still not much better. Here's some images of the issue.



Here's a image of the mold

This issue just developed, She cleaned the molds, but that didn't help at all.
Any help will be appreciated!!
 

[Billmo]

I'm no expert and I am sure most of them will comment and give you great explanation and advice. From my experience that looks like the plastic is too hot and its being pulled in, or she may be shooting hot and fast and its causing air bubble issues. 

Again I'm no expert but when I have pitting/dent issues I'm usually shooting too fast and too hot.

[DobynsTriton]

I'm gonna agree with bill on this one looks like its being shot too hot & fast.

[MO QWACK]

Looks like the vent holes are to big or plastic is to hot. All the flash is near the vents. Cooler and slower should help. Great looking mold

[toadfrogbaits]

The mold is an LSBug from Lakeside Baits . I know his molds well . Has to be happening during the injection process because a mold in and of itself dose'nt just devellope  a problem without being damaged in some way . So I'm inclined to agree It's heat or injection related . I'm assuming the mold is being topped off after each shot . Sometimes you get dimples from not having enough plastic in the sprue to draw from as it cools . Been there done that more than once . 

[andrewlamberson]

I'm 99% sure it's due to the hot center plastic cooling slower than the skin and you are getting "dents". There are a bunch of posts/thread on "dents" and I think you will see it looks the same. The skin cools first and then the center. When the center cools it contracts and has to pull from somewhere. It's what makes "splay" marks in injection molded parts and is called "differential shrinking".

So...inject the bait at the coolest temperature that you can to get the mold to fill. Make sure you are using (and yes...I am going to say it!!!) a good digital thermometer and make sure the plastic is uniform in temperature (stir it) so you don't have hot spots.

[BareKnuckleJigs]

The problem is Injection SPEED.  When the plastic is filling the cavities, the ribs are trapping air bubbles.  I have the BT 3.5" Ringworm that is hard to shoot because the ribs trap air the same way.  I get better baits by tilting the mold about 45 degrees so the cavities are at about a 45, and inject very slowly.  This will let the ribbed cavities fill while slowly letting air out of the vent that runs along the Tips of the Ribs.  When I say tilt at a 45, I'm talking about End to End, picking up one end of the mold right before you start injecting, and holding that angle through the injection, then once the cavities are full, set the mold back down as you're holding injector pressure for 5-10 (or more) seconds.

[BareKnuckleJigs]

And when your mold is tilted, make sure the Head (that fills first) is lower than the tail.  The Tail (since it fills last) should be higher than the head when the mold is tilted and being injected.  And inject very slowly.  SLIGHTLY warmer temps may help also, as the plastic needs to stay fluid and easily flow/fill when injecting a Ribbed Bait.  And the hotter the plastic is, the longer you'll want to hold injector pressure after the mold is full, to feed plastic to the cooling/shrinking plastic in the mold.  But your #1 problem here is you're trapping air, so tilt, raise the tail-end of the mold right before you start injecting plastic into the mold...as much as 45 degrees.

[BareKnuckleJigs]

Did I mention inject very slowly?  Painfully slow.  And that's PART OF why your plastic needs to be good'n warm...because you're needing to inject so slow...and the plastic needs to stay hot enough to flow into the small parts of the cavity.

[BareKnuckleJigs]

Looking at that bait, make sure that the "arms" of that bait are at the Top and Bottom when injecting, do not "lay the mold down" so the arms are left-and-right (horizontal).

[Shane70]

I agree with the majority of the other post on this subject, plastic is too hot and injecting too fast.
Don't beat yourself up over this. Its a Learn-as-you-go Hobby

[tboxfish]

Thanks everybody for the info!!!!!
She stirs the plastic very thoroughly, but I certain that she is injecting it too fast!!!! I can't put all the blame on her - LOL. I made her color formulas & helped her get going, so I'm sure I told her to inject it fast, not knowing this issue would happen.