Molding Plastic - Can This Thing Be Done?

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Molding conventional plastic bottles and jars with re-entrant screw threads presents significant challenges, as the design complicates mold removal, making it nearly impossible without breaking the mold. The discussion highlights concerns about the cost implications of using alternative molding methods, suggesting that they could be significantly more expensive than traditional processes. Additionally, the feasibility of inserting and turning the bottle top without tools raises practical design issues, particularly regarding the engagement of threads. Suggestions for alternative designs include snap fits or interference fits, which may simplify the manufacturing process. Overall, the complexities of the current design make conventional molding methods impractical.
Blokle
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Hi,

1) Can this thing be molded using methods and materials that are used to mold conventional plastic
1.1) bottles?
1.2) jars?

2) How much more expensive will it be (percentage and/or absolutely ) compared to 1.1/1.2?

3) In a case that it is impossible or much more expensive than conventional bottles/jars - do you have ideas for alternative design to achieve the same functionality?

Thanks
 

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I think this is pretty much mpossible, because of the re-entrant (or internal) screw threads. Once you have filled the mold, the only way to get the bottle out would be to break the mold. That would be OK for casting with a sand mold that is only used once, but you can't "unscrew" a re-useable mold from the bottle.

Apart from that, I don't understand quite how your "mid height" connectors are meant to work. How can you insert the "bottle top" and then turn it without using tools, since you will finish up with no free space between the bottles except the thickness of the "nut" between the two opposite-direction threads? And if the two threads don't engage at the same time on both bottles, one side is going to be fully screwed in before the other.
 
How about snap fits? might be much easier to make. Or an interferrence fit.
 
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