Polypropylene molding
Polypropylene molding
(OP)
Hi, I have been experimenting with "molding" polypropylene. I have been using a polypropylene suture material that is 0.010" and 0.007" in diameter. I have been tightly wrapping the suture around a fixture I made and then heating it in the oven to about 350 degrees F to keep its shape when removed from the mold. This has worked but does not keep its shape as well as I would like. I have done some research but could not find properties for just PP suture (I am assuming that the properties are different than raw PP). I also realize that this is a softer plastic and can be deformed easily but it seems to be deforming easier than I want. Is there anything that can be done to harden this PP suture after being "molded"? Keep in mind it is a product that will be used in a surgical procedure. I have tried coating it in a silicone with little improvement.
I am also currently looking to get this injection molded, knowing that is the route that we will go with it eventually, but having issues finding a vendor due to its complex shape and small size. If anyone has vendors that may be up to the challenge let me know.
Thanks.
I am also currently looking to get this injection molded, knowing that is the route that we will go with it eventually, but having issues finding a vendor due to its complex shape and small size. If anyone has vendors that may be up to the challenge let me know.
Thanks.






RE: Polypropylene molding
Mike Halloran
Pembroke Pines, FL, USA
RE: Polypropylene molding
You are unlikely to mould .010 diameter PP longer than about an inch - maybe two long (gut feeling). Polymers have defined calculable maximum flow lengths.
You will not be able to "harden" the PP.
I always assumed sutures were nylon?
H
www.tynevalleyplastics.co.uk
It's ok to soar like an eagle, but weasels don't get sucked into jet engines.
RE: Polypropylene molding
At this point I am in desperate need of an injection mold company that can work with me with getting this part molded. Most companies I have tried says that it is too small and complex or they just don't do parts like this. I may just have to figure out a way to mold it myself.
RE: Polypropylene molding
Would your part be producible with a 3d printer - type process? Without more detail about what your part looks like (maybe a picture would help) and what features of the wrapped part need to be preserved, it would be difficult to give any advice regarding molding.
RE: Polypropylene molding
On the bright side, after further searching I was able to find a handful of micro molders, in which some are specific to the medical field. Some of these companies are:
http://www.mtdmicromolding.com/
http://www.micromoldinginc.com/
http://www.micromolderie.com
They were very anxious to help!
RE: Polypropylene molding
So, before abandoning this make sure you get some manufactured PP fiber which is readily available.
Dr. Chris DeArmitt - FRSC
www.linkedin.com/in/chrisdearmitt/
RE: Polypropylene molding
Thanks
RE: Polypropylene molding
Dr. Chris DeArmitt - FRSC
www.linkedin.com/in/chrisdearmitt/
RE: Polypropylene molding
Dr. Chris DeArmitt - FRSC
www.linkedin.com/in/chrisdearmitt/
RE: Polypropylene molding
Now that you have found some molders who interested, this would be a good time to back up a bit, and figure out what properties you actually need, and start designing a product within the limitations of the processes you can get.
Mike Halloran
Pembroke Pines, FL, USA
RE: Polypropylene molding
Dr. Chris DeArmitt - FRSC
www.linkedin.com/in/chrisdearmitt/