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Author Topic: Air Bubbles-standard Injection Machine  (Read 91 times)

christianpindichi@yahoo.com

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Air Bubbles-standard Injection Machine
« on: November 18, 2016, 07:33:09 am »
Hi guys!
After 2 months of testing, I still have problems with air bubbles. I followed all steps( less stiring, waiting air to exit an after put pressure in cavity, etc) . I tested the plastisol in microwawe, no bubbles.
Still have problem with upper pieces from molds, an air bubble like a tear , big enough, is there. The problem persists to all molds that I have, so for sure it s not a mold problem. Maybe I am doing something wrong....please help&advice!!
Thanks!

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Rick

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Re: Air Bubbles-standard Injection Machine
« Reply #1 on: November 19, 2016, 06:02:22 pm »
Is the mold runner hollow also? If so, then you will need to increase the amount of time that you leave the valve open when injecting. Plastisol shrinks when it cools and leaving the valve open longer will allow more plastisol to flow into the mold as the cavities cool.
If the runner is full, then decreasing the amount of time that you leave the valve open will allow the trapped air to escape into the runner.
 I know that you are using materials from a European supplier and I have no experience with the products. Try using plastisol, colorant and additives from a different manufacturer. The only other customer that I've had with air bubble problems turned out to be caused by poor quality plastisol.
There are no parts in the injection machines that will cause air bubbles, other than over stirring with the mixers and an empty pot on the Pro Series.
 

christianpindichi@yahoo.com

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Re: Air Bubbles-standard Injection Machine
« Reply #2 on: November 21, 2016, 04:06:13 am »
I did. the runner hollow remains like in the pics below. problem is especially on the upper mold cavities, and big baits. For example at SIlver fish the smallest is almost no problem. but at Swim Worm 3" and other big baits it is. I will try a different supplier of plastisol.

Rick

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Re: Air Bubbles-standard Injection Machine
« Reply #3 on: November 21, 2016, 07:46:38 am »
I repeat...
Is the mold runner hollow also? If so, then you will need to increase the amount of time that you leave the valve open when injecting. Plastisol shrinks when it cools and leaving the valve open longer will allow more plastisol to flow into the mold as the cavities cool.

Watch the sprue and runner immediately after injecting a mold and you will see the plastisol shrink as it cools. If there is not enough plastisol in the runner, air will be drawn into the gate area of the upper cavities. 

Rick

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Re: Air Bubbles-standard Injection Machine
« Reply #4 on: December 02, 2016, 06:37:09 pm »
After watching the video that you sent of your injecting procedure the cause of your problem became very obvious. Your machine temperature was at 421 degrees F. which is way to hot...
As the set up and operating instructions stated the machine temperature should be set at around 340 degrees +/- 10 to 15 degrees. I can't understand your reasoning for setting the machine temperature so high but overheating plastisol to such a high temperature will render it useless and it will not flow into any mold.
The fumes from the super heated plastisol must have been horrific.

christianpindichi@yahoo.com

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Re: Air Bubbles-standard Injection Machine
« Reply #5 on: December 03, 2016, 04:24:28 am »
Hi Rick and thanks for youre help. I set up the temp at 421 farenheit for 2 reason:
-the plastisol supplier recomands a working temp between 160-230 celsius(320-446 farenheit)
-when open the pot at 340 farenheit the upper part of plastisol did not looked melted
 I didn't realized that the temp showed on thermometer was just down side of the pot. Even now it worked, I mean at 340 -343 farehheit-no air bubbles in the head, there is still unmelted plastisol bonded on the mixer proppeller. My conclusion is that I must wait longer at 340-350 before injection...to give time to the plastisol around the proppeller to melt.
thanks! nice day!

Rick

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Re: Air Bubbles-standard Injection Machine
« Reply #6 on: December 17, 2016, 09:05:41 pm »
You could have saved yourself and me a whole lot of time and trouble if you would have just followed the supplied instructions to begin with.