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Old 03-10-2015, 11:22 PM
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Meulen Meulen is offline
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Join Date: Jul 2009
Years Playing: 13
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Posts: 507
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Where to start....

Bear with me as I try to explain the basic concept behind how a mold works for a disc. As always, if you have any questions at the end, I'd be more than happy to answer them.

I'd like to preface this long post by stating that I intentionally left out almost all mold components to those that are familiar with injections molds. This includes leader pins, sprue bushing, vents, springs, cooling channels, clamping plates, etc. etc. Here we go!

First we'll start with a key:
Red Plate = Cavity
White Plate = Stripper Plate
Blue Plate = Core
Green = Disc
Pink = "Spacer"
Yellow = Modified Disc


Below is a cut-away view of the mold. Refer to the key above if necessary. The cavity makes the top surface of the disc, the core makes the inside rim and underside of the flight plate, and the stripper plate makes the underside of the wing and in this case, half of the leading edge. Any place where 3 colors intersect in the image, there will either be a parting line (Red/White/Green), or a witness line (Blue/White/Green). The green area can be thought of as either the disc, or negative space the plastic will fill to create the disc.


The next image shows a cut-away as if the mold were opening. The stripper plate "strips" the part, in this case a disc, off the core, or plug. This is usually spring actuated with shoulder bolts to prevent over travel. As pictured, the disc stuck to the cavity plate, and would remain there until removed by an operator. This view shows the stripper plate geometry a little better.


Here's where I try to explain away the "spacer". I added a spacer, shown in pink. As with the green area before, the yellow can be thought of as both the disc and the negative space the plastic will fill. The spacer I added is 0.100" thick. You can see the nose is now more blunt. However, adding a spacer effectively shifts the cavity plate by 0.100", so the flight plate is also now 0.100" thicker, for a total of 0.170". I personally have never handled a production disc with a flight plate that thick. Hence, I still don't believe "spacers" are utilized to modify molds.


Next I'll throw in two "exploded views" just because. You'll notice the stripper plate shown doesn't look too different from the Discraft screen-shots I posted earlier.



Lastly, here is a video that shows a short animation. When the mold opens the cavity and the stripper plate travel together until the stripper plate reaches the end of travel dictated by shoulder bolts. The cavity continues to open to allow room for the disc to be removed. Using either a robot or an operator the disc can then be removed from the stripper plate. Depending on where the undercut in the mold is added, the disc may continue to travel with the cavity after the stripper plate has stopped, where the disc would then be removed from the cavity plate instead.

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