Anyone have experience with the particular style of living hinge that's used on shampoo bottles and various condiments?
I think it's known as a Butterfly Hinge because the profile where the hinge meets the cap looks like a butterfly or bowtie.
Basically the cap has two positions (open and closed ... duh! ... LOL) that more or less lock in place.
Any info or pointers would be greatly appreciated.
Thanks in advance,
Willy
I have messed around with idea of living hinge system on some plastic vacumed boxes i was designing but i droped that in favor of regular metal hindges.
As far as i could gather, the point is in making sure tension is moved from hindge line so it doesnt break after a while. My idea was to reinforce hindge center in a way that makes bending deformation spreads to one of the "wings".
Here is some info.
Hi Willy,
No direct experience buy have been involved with a number of flexing plastic parts (the flexing was part of the function) and years ago in a true hinge but that was before this bottle top type was born.
If I was starting from scratch I would get and existing cap that you like or more than one and I would cross section them to look in detail at the profile and sizes involved as these are very important. If you were very keen you could use some sort of edge measure or CMM to pick up the geometry. Obviously there may be some designs covered by patent so you would have to check that aspect.
As far as I know this type closures are all moulded in Polypropylene which has a particular molecular structure that makes it great for spring and hing type applications BUT with the proviso that you need to ensure several things in the part.
There are other materials such as Nylon sometimes used for a single hinge closures but despite its strength the much shorter molecular chains and hydroscopic tendency make it less suitable in my mind.
Not sure if this helps but I hope so.
Regards,
Brent Drysdale
Thanks for the info guys. Every little bit helps.
Turns out our customer, who molds megazillions of caps & closures, bottles and widgets, was not all that enamored
of the elusive Butterfly Hinge due to the shape of this particular cap. It turns out, also, that they can provide some piece
part "go-bys" and old-school tool designs of various styles of hinge that they are still fond of.
It's starting to look like all I'm gonna have to do is wade through a labyrinth of fuzzy paper scans, stand on my head,
and work while looking in a mirror. Can't wait to get started. LOL.
Actually, I'm almost finished with round one. Review this afternoon.
Thanks again, guys.