CAD software discussion forum > 3D CAD/CAM > Nothing to do with VX but I have to ask!

Nothing to do with VX but I have to ask!

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Kevin

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Registered: 2004-4-26

Message 1 of 9

 Nothing to do with VX but I have to ask!
14-03-2005 03:22 . pm | View his/her posts only
This has nothing to do with VX aside from the fact that I'm designing parts using it! I'm designing a medical component system right now that uses a syringe element in it. Standard syringe barrels tend to be made in polypropylene with zero draft angle on the inside. My question is how do they mould that?? Every moulder I've asked that I use doesn't have a clue.

My experience of PP as a material is that it shrinks like crazy onto the core so a zero draft "core" is asking for trouble.

Any ideas anyone? Its not critical to the project but as a curious designer I'd really like to know!

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ChrisWard2k2

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Registered: 2011-11-22

Message 2 of 9

14-03-2005 07:44 . pm | View his/her posts only
Hi Kevin


There is a (VX User) company in the UK that produces this kind of medical equipment. Ask IDS for a contact if you find you need some help with your project.

How do you know the draft is zero? It might be possible to have the inner seal design accomodate say, a 0.25deg draft. The PP used - must be a well developed formulation for this type of product, since there are other factors involved concerning function etc. A standard syringe barrel incorporates a shoulder. Maybe the cores therefore are pins, with the shoulder formed in the cavity, allowing a core-side stripper plate to eject the parts.

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Kevin

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Message 3 of 9

15-03-2005 04:29 . am | View his/her posts only
Thanks Chris, once again a mine of great info!

I'll give IDS a call and see who the company is.

Thanks

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OldForumPost

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Registered: 2012-1-14

Message 4 of 9

18-03-2005 04:57 . pm | View his/her posts only
Kevin,

Could you please post your findings, I am curious now too! I think I have an idea but I design blow molds, not injection.

Thanks,
Steve T

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Steve

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Registered: 2004-10-9

Message 5 of 9

19-03-2005 11:39 . am | View his/her posts only
Chris is correct in his assumption. We've created tools similar to this, EXACTLY as Chris has suggested for medical part molders. Stripper plates are a PITA!

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Kevin

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Registered: 2004-4-26

Message 6 of 9

19-03-2005 03:39 . pm | View his/her posts only
Yes, Chris and Steve are right. I've got a contact in Australia who designs these things and he said exactly the same.

Now the only problem is doing the soft tools. My toolmaker has plans of doing the device side on with a manual side core for the barrel. I'm not sure how good this will be - it will be a bugger to get the parts off the core manually. He knows a lot more than me about tooling and moulding so I'll trust him!!

When we get the parts I'll report back!

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Kevin

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Message 7 of 9

21-06-2005 05:23 . am | View his/her posts only
For interest (I did actually mean to do this sooner!) we did an aluminium tool for clinical trials with polished zero draft side pull core (manual ejection) and it worked a treat. Start to finish in 2 weeks, including a part design change after week 1.

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ChrisWard2k2

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Registered: 2011-11-22

Message 8 of 9

21-06-2005 07:16 . am | View his/her posts only
A good turn around, especially since you had a design change too. I'm sure the IDS guys would love to volunteer for the clinical trials........

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Kevin

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Registered: 2004-4-26

Message 9 of 9

21-06-2005 09:12 . am | View his/her posts only
Ha Ha! I very much doubt it Chris......lets just say this thing goes where the sun don't shine :-) and then some!
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