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Fish_N_Fool

Update on injection mold problem with laminate

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Hi all, Here is some new pixs of the baits as they come out of the mold. We are trying to get a good top bottom laminate with the Chartreuse color on the belly of the bait and the dark Watermelon Green on the back of the bait. I know this can be done but not sure why ours are not coming out. It is as you can see it is a pie mold feed with 2 injector pumps from the top and bottom at the same time & the plastic is kept apart in the runners by a thin plastic sheet till it enters the bait cavity. We have also tried it with out the plastic sheet and they looked about the same. If you think you know the fix as to why this is not working please let me know, also If any one out there pours laminates in a large quanity in an injection mold please get hold of me in a PM

This is the top or back of the bait;

Sink-N-Foolmoldtop.jpg

This is the belly or bottom of the bait;

Sink-N-Foolmoldbottom.jpg

This is a detail of the center of the runners;

Sink-N-Foolmoldcenterdetail.jpg

Here is the bottom side of the runners;

detailtbottomside.jpg

Edited by Fish_N_Fool
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pictures 1 and 2 and then 3 and 4 are not the same pour correct?.

in pic 1 the chart was just before the watermelon

pic 2 water melon before the chart

timeing was off a tad.

to make a pie mold succesfully work in 2 color laminates and its very hard to do hand injection. ( hand meaning anything that isnt automated via a timer) you should have the bottom mold with a seperate chamber running to the bottom of the mold and the top mold with a chamber running to the top mold. however due to it being round its a little difficult to do. and using a non automated injection system is going to be tough. much easier to shoot in a straight mold when running non automated.your success rate is much better do to timming.

The thin plastic sheet is a good idea also.

one thing you might want to do is make sure your bottom and top ports are Identical in size and shape. from the pics I don't see a bottom port were the plastic is shooting to colors, looks like it shoots one then pushed the other out with the other color, hence timming off.

Edited by Delw
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pictures 1 and 2 and then 3 and 4 are not the same pour correct?.

All the pictures are from the same piece just from both sides.

to make a pie mold succesfully work in 2 color laminates and its very hard to do hand injection. ( hand meaning anything that isnt automated via a timer) you should have the bottom mold with a seperate chamber running to the bottom of the mold and the top mold with a chamber running to the top mold. however due to it being round its a little difficult to do. and using a non automated injection system is going to be tough.

Del I dont have the machine {I farmed out the injecting to company back east} but these are machine injected not hand injected . As far as I know with timers and such but they cant get them to turn out. I can see from this that it looks like the chartreuse is getting to the mold first then the green comes in later. so that a place to start.

one thing you might want to do is make sure your bottom and top ports are Identical in size and shape. from the pics I don't see a bottom port were the plastic is shooting to colors, looks like it shoots one then pushed the other out with the other color, hence timming off.

Not sure i have a clue what you mean here

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From a theory point of view, I see the problem as the narrow neck, at the entrance to the bait. This restriction will cause turbulence and cause the plastic to mix.

You could try extending the plastic divider through past the neck, to see if that settles the flow. But the ideal solution would be to remove the neck, so you have a smooth laminar flow into the bait cavity.

At least your worm body is smooth, with no worm segments. These would make the problem worse.

Like I said at the start of this post. This is theorizing. It would be nice to try the idea out on a PoP or resin mold before cutting metal.

Dave

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+1 what Dave said as well.

IN picture 3 and 4 they dont looke like they are the same batch just turned over if it was you would see water melon on the bottom part of the chartrue and vise versa

plus picture 4 doesnt not have a injection port on the bottom ( you can see the top is perfect minus a scratch) unlike picture 3 that you can clearly see a injection port.

There are many types of injection machines, a pie mold is generally used on a low budget injection machine, more of a hand machine so to speak. basically its a big pressure pot you turn the valve on by hand or a hand switch.

There is alot of these machines out there and they do very very nice work but 2 laminates are pretty hard to do, due to the nature of the pressure pot and the timing of each shot.

Professionals injection machines are the ones that have water cooled molds and and properly placed ports these will give a user almost 100% control on anything from laminates- swirls to different color wings.

on the part about the bottom and top being identicle, theroreticlly(sp)

if you have a 1/2" hole on the top and a 1/2" hole on the bottom and both top and bottom molds are identical and you have equal pressure of the liquid going into each hole the plastic from the top and the bottom would meet in the middle and spread out words with one being on top and the other color being on the bottom giving you a laminate. however if one has a bigger hole or more pressure than the other one color will dominate the other color.

could you take a side shot of the web, i would like to see how the 2 colors are mixing, from the pics on 3 and 4 it lookes like there is no mixing and there is no port on the ones side. it looks more like they shot one color then the other color or both colors on one side.

IN thinking about this for a while you may have some success by making a divider out of sheet metal that goes between the 2 halves just to the opening of the ports on each cavity.

basically mill your mold down xxx amount on each side and and fabricate a blocking plate in there. this will keep the plastic mixing in the web until it hits each cavity. However if you dont have equal everything (pressure hole size etc etc) on both sides one color will be more visible then the other.

if you dont understand about the blocking plate email me a pic of the mold and I will doctor it up in a photo program so you understand better.

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Ok here is what I got and all I know. If we make the opening into the bait cavity larger the bait will no longer have the rounded head that I need it to have. So not sure if we could open up the neck without ruining the bait's shape.

These are pixs of the top and bottom ports. First top then bottom;

moldinjectionportdetailtop.jpg

moldinjectionportdetailbottom.jpg

Next is what the baits look like as they come out of the mold these are just layed on their side not spread out like in pixs at the begining of this post;

baitsfrommold.jpg

Last is a bait that is cut into 1/4 long segments;

segmentedbait.jpg

I do not have any pictures of the mold itself.

Edited by Fish_N_Fool
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Wow, it is close. So not a neck problem. All I can think of is a difference in temp between the two plastics, giving a difference in viscosity.

Is it the same color that always wraps?

Is it always the top (or bottom) that always wraps?

Dave

Dave it seams to be both, in differant parts of the bait. Here is a close up of the head of the bait where the dark green is wrapping around the Char.

greenoverchar.jpg

This is a blow up of the tail section where the Char. wraps the green.

Charovergreen.jpg

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Machine laminates are all about pressure and temperature. Also remember darker colors absorb more heat. Your problem is your darker color is hotter than your lighter color. As a rule of thumb, you always start out with equal temperature and pressure. Timing mainly has to do with making sure that your bait is fully formed. I've been working today on a color that's similar to what you're after. For some reason a darker green such as watermelon or black melon always wants to wrap a lighter color. Baby bass is another color that is very hard to laminate, things have to come together just right. You're more than welcome to have your injector to contact me. PM me for contact info, and maybe I can talk him through what he needs to do. It's two different machines but the principles are the same. Sometimes you even have to let the temperatures meet, what I mean by that is if one temp is dropping and the other is rising you may have to wait for the moment in which the temps line up to make the actual injection. This will slow down production some, but it's better to be a little slower and make good baits than waste plastic. If I need to talk to you more about this, like I said, PM me. There's a couple of guys out there that don't like for you to tell machine secrets. I agree, it's silly. Out of 67 shots this evening, there was probably 15 that only half the laminates came out right and it was all because one temp was hotter than the other. I'm not sure how big your bait is, remember, the further plastic has to travel, the more it forgets what it's supposed to do. It may not seem like it, but you guys are on the right track, that's the way my first ones came out.

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Carolina mike tnx for the info and offer of help. I will be sending youy a PM shortly, The baits are 6" and 5" all the pixs i have shown are of the 6" ones.

One thing I forgot to tell you all is the plastic formula I use is an extra heavy salt mix. Way more salt then any one else puts in, That may have some thing to do with it also.

Edited by Fish_N_Fool
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Hey - I have absolutely no exprience with injecting but have been following this thread and had a couple ideas. Might be good food for thought for you.

In the pictures where the chartuese is wrapping more around the darker green it appears from the picture the chartuese section is tapered down more than the other. Or, there's less volume for the Chartruese to fill. I assume the injecor inserts some degree of pressure which I would think would force the plastisol up or down around the mold (depending on how the mold is setting).

I dont' know if you can adjust the pressure when injecting, but I wonder if less pressure would help? Or if it is possible to adjust how much plasisol is being injected through those less or more volume areas? It just looks to me like the plastic is forced there, with no where else to go.

As I said I have no exprerience with this, but might give you some food for thought!

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It's not going to be easy to get perfect laminates with a pie mold. A single runner with the cavities machined off of each side of the runner is much easier to keep the two colors running even. It is about temp, time, preasure and the derometer of the plastic that is used. In some cases, the harder the plastic the hotter you need to run it. but it's also about the configuration of the mold that will give you greater success.

I can have a mold machined and shoot these baits for you, if you want?

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