Plastic cooling inside of injector

[Glideb8]

Hey guys,

 

I had a question.  I bought a plastic injector and also made an injection mold for soft plastics.  I'm heating the plastic to 320(I'm using MF Saltwater) and it's perfectly fine, no bubbles, very fluid.  I tried sucking it up into the injector and also pouring into the injector and the same result about halfway into injecting the plastic into the mold- The plunger stopped, so I opened it and there is always a plastic plug inside no matter what I'm doing.  I've read that guys have kept their injectors warm in a george foreman grill(lol) but I'm thinking that has to be the problem.  The injector has to be almost hot if not hot,  Below is a picture of what's happening.

 

Any info would be greatly appreciated!

 

[SlowFISH]

That happens to nearly everyone unless you are using a presto-pot and can keep the injector tip down in the heated plastisol between injections.  

When I'm doing small batches and using microwave/pyrex cups - I keep my injector up on a couple blocks of wood and put a small alcohol lamp  below the tip to keep it hot.... this probably OVERHEATS the tip/injector at times and honestly - isn't the safest thing to do compared to using something like a foreman grill- but it works on minimizing the "plug" you get in your photo.  And it's not just the tip that is causing it - it's the plunger as well... BOTH have to pretty hot.

Get and keep that injector hotter and you'll minimize/eliminate that plug - but in my experience - its really tough to do unless your using prestos and let the injector sit down in the plastic.

  J.

 

[Jig Man]

You might try filling it up, quickly emptying it back in the container, fill it up again and see how it goes.

[Apdriver]

When I’m heating my plastic in a microwave, I get one injection for the most part because as you wait to demold ( roughly 2 minutes) it will set up in your injector anyway (Cavity count is important here)That’s why we evacuate the injector after the shot. To prepare your injector, you can preheat it with some type griddle or most of the time I use a propane torch with a piezo igniter on it and heat the injector with that. Keeps it from plugging up. 

[Glideb8]

36 minutes ago, Apdriver said:

When I’m heating my plastic in a microwave, I get one injection for the most part because as you wait to demold ( roughly 2 minutes) it will set up in your injector anyway (Cavity count is important here)That’s why we evacuate the injector after the shot. To prepare your injector, you can preheat it with some type griddle or most of the time I use a propane torch with a piezo igniter on it and heat the injector with that. Keeps it from plugging up. 

I'm making a 6" swimbait and it's not short in height like a open pour, so that's why I need to unplug the injector, then refill it to make sure the entire cavity is completely filled.

Thanks for the info, everybody!

[wallyc14]

If that’s the case you need a bigger injector. More capacity.The plug at the end when shooting is pretty normal when using a mic to cook. As said above about using presto pots that’s the only case you don’t get a plug.

i do have a few molds I have to use a 9 oz injector  To fill the mold . Most of the time a 4 oz normally gets the nod.

[Glideb8]

2 hours ago, wallyc14 said:

If that’s the case you need a bigger injector. More capacity.The plug at the end when shooting is pretty normal when using a mic to cook. As said above about using presto pots that’s the only case you don’t get a plug.

i do have a few molds I have to use a 9 oz injector  To fill the mold . Most of the time a 4 oz normally gets the nod.

Ok, good to know.

[Apdriver]

If you preheat your injector, you should be able to shoot injector til it’s empty, reach back to Pyrex and draw more plastic then reshoot your Mold to fill it. I do this when shooting multiple molds and it works. You must preheat your injector and possibly the mold too.

[Basseducer]

UltraMolds has a sweet little sand alone injector heater. Keep your injector hot and clear.

[Glideb8]

11 minutes ago, Basseducer said:

UltraMolds has a sweet little sand alone injector heater. Keep your injector hot and clear.

I'll check it out.

[R Glover]

    I use a propane torch to preheat my injector, suck in the plastic-shoot your mold and then put the injector back into the cup of hot plastic, push all of the plastic out of the injector & you are ready to shoot again.