Maurice
23rd September 2016, 05:47 PM
First off I want to make it clear I'm not an injection molding expert. Rather I'm an inventor that is using injection molding for the first time. I'm working with a small scale injection molder in Michigan so I could get custom support. So far he's been doing a great job and the molds turned out great. The problem is now we're getting into an area beyond his expertise and I'm wonder if others in the injection molding community could help out.
The problem is my invention rotates at 800 RPMs and some of the injection molded parts are melting. Below is an image of the design (it's an electric spinning wheel for converting wool to yarn). The central part spins and where it is sitting on that bracket is where it melts. I've been working with adjusting the drive band tension and I can get it working at slightly slower RPMs, but I'm hopeful there is some material change we can do that works for this kind of use case. I have a 3d printed ABS version of the parts that don't melt, but they are also much rougher and I wonder if that has something to do with it?
The things that I think matter are: melting point (higher is better), thermal conductivity (better heat dissipates the better), friction (less is better).
We have tried:
* HIPS w/ 50:1 lube ratio
* HIPS w/ 25:1 lube ratio
* Acetal w/ Teflon lube
* PE w/ Teflon lube
The PE seemed to work best, but only had those for the braces and they did still have melting issues. Basically we are trying to mold a bushing and shaft that doesn't melt. I'm wondering if people here have suggestions on what types of plastics would work best for this? Also if you have ideas on mold geometry to reduce melting that would help that would help too.
152
The problem is my invention rotates at 800 RPMs and some of the injection molded parts are melting. Below is an image of the design (it's an electric spinning wheel for converting wool to yarn). The central part spins and where it is sitting on that bracket is where it melts. I've been working with adjusting the drive band tension and I can get it working at slightly slower RPMs, but I'm hopeful there is some material change we can do that works for this kind of use case. I have a 3d printed ABS version of the parts that don't melt, but they are also much rougher and I wonder if that has something to do with it?
The things that I think matter are: melting point (higher is better), thermal conductivity (better heat dissipates the better), friction (less is better).
We have tried:
* HIPS w/ 50:1 lube ratio
* HIPS w/ 25:1 lube ratio
* Acetal w/ Teflon lube
* PE w/ Teflon lube
The PE seemed to work best, but only had those for the braces and they did still have melting issues. Basically we are trying to mold a bushing and shaft that doesn't melt. I'm wondering if people here have suggestions on what types of plastics would work best for this? Also if you have ideas on mold geometry to reduce melting that would help that would help too.
152