Molding challange how do you do this one?

Hey fellow metal heads, I have become very proficient at making silicone, and
metal molds as of late, and making plastic parts, but I have a great challenge
facing me. We are talking about a taking a one inch steel ball and molding
plastic around it so essentially what you would have is a steel ball with a 1/4
inch plastic coating on it. These have been made so the real question I have
that may help me figure out how to do it, is how did they do it? How would an
injection mold shop do this? This is a tough one for me, but I was hoping
someone may have worked in a shop and seen this done. Anyone care to take a
stab at this one>?
Thanks
Tom
"Democracy is two wolves and a lamb voting on what is for lunch. Liberty is
a well armed lamb protesting the vote."
Reply to
NoSheeples
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Maybe you can support the ball on steel pegs, fill in plastic around it, then while still soft(?) remove the pegs and fill the holes, hoping for a weld or at least a good seamless joint? Maybe use epoxy to fill in, using a vacuum chamber to ensure no bubbles?
Tim
-- In the immortal words of Ned Flanders: "No foot longs!" Website @
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Reply to
Tim Williams
What kind of plastic are you molding over the ball? If soft you might be able to dip it. Hard plastic might be easier to make a shell and seal the ball inside.
Reply to
dann mann
Has to be pretty hard. It will be urathane resin.
Tom
"Democracy is two wolves and a lamb voting on what is for lunch. Liberty is a well armed lamb protesting the vote."
Reply to
NoSheeples
A tiny seem is ok. I was thinking along the lines of a jig like you mentioned. something to support the ball in the mold. This is a tricky one.
"Democracy is two wolves and a lamb voting on what is for lunch. Liberty is a well armed lamb protesting the vote."
Reply to
NoSheeples
No Sheeples wrote: (clip) Im using a thermal set 2 part plastic so melting is not a problem.(clip) ^^^^^^^^^^ I did something like this once using a two-component resin system. I made spacer blocks out of the resin, and used them to hold a leaf in position while I poured the same resin over the leaf. After it cured, the spacers were not visible. They have to be smooth so no air is trapped on the surfaces, or you will see bubbles. In fact, bubbles were me no one problem. I am told that pulling a vacuum would have helped.
Reply to
Leo Lichtman
Noooooo! That would go right through the drum head! This is for plastic coated pinballs! I allready make drum beaters. Here, you can check out what I make here.
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"Democracy is two wolves and a lamb voting on what is for lunch. Liberty is a well armed lamb protesting the vote."
Reply to
NoSheeples
Yea, I think the ticket here is going to be makink a plastic jig that looks something like ball and jacks so that the ball can rest centered in the mold while I pour the plastic in. Gonna be a tough one. Keep the ideas comming!
"Democracy is two wolves and a lamb voting on what is for lunch. Liberty is a well armed lamb protesting the vote."
Reply to
NoSheeples
When I look at a rubber ball it's usually two hemispheres joined together. Sounds like yoiu are making the same thing with metal instead of air in the middle.
Reply to
Beecrofter
Coaxial DC electromagnet above the ball, horizontal sensing coil (axis vertical) surrounding the ball and mold, and feedback controls system. The coil senses ball height by change of inductance and drives the control system to power the magnet, reducing current if the ball is too high and so forth. The field would be divergent (radial gradient) so the ball would stay self-centered horizontally. The control system would need to be non-linear because the force exerted on the ball by a given magnetic field varies inversly as the square of the distance between the ball and the electromagnet.
No pegs, no seams!
Post photos!
Reply to
Don Foreman
A little to high tech for me, but I like it!
"Democracy is two wolves and a lamb voting on what is for lunch. Liberty is a well armed lamb protesting the vote."
Reply to
NoSheeples
I made many thousands of steel cores for checks balls, as you are describing. The split mold had grooves to position the 3 pins that supported the core in the mold. Steel pins were used.
Reply to
Jon
What about panning? This is how they make many candies, such as jelly beans and jaw breakers.
You take a bunch cores and put them in a rotating drum then begin pouring stuff on them. Let them roll around, sometimes they run heated air inside the drum to dry them. Then do it over to get another layer.
You might have to do something to the surface of the ball to get the stuff to stick to. Here's a video of the process:
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If you only need to make a few balls at a time, you can make you own panning machine by soldering 2 salad bowls together and connecting them to a food processer to get them spinning.
Good luck. I love to hear if you try this. Jason walter
NoSheeples wrote:
Reply to
Jason Walter

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