Buckshott00
Bioengineer
Hello All,
Sorry for the cross-post thought maybe there might be more visibility here.
I'm looking for tips to improve over-molding of two very similar grades of Hytrel. I'm trying to improve the molding or other process parameters to get better bonding between extruded tubing of Hytrel 4056 and the Injection molded 3078, hopefully resulting in better component performance.
My application is every harsh with a steady state RPM of 2500-5000 for up to 3.25hrs. The good news is the component is intended for single use. I just need to make the part resilient enough to resist elongation-delamination-trib "death cycle". It just needs to last a bit longer than current state.
Currently the part is partially surviving ~1-2hrs, but with unacceptable elongation (post-delamination) resulting in abrasions w/unacceptable amounts of particulate. I believe that some amount of delamination and particulate is unavoidable, but maybe there are things I could do to improve its performance?
We're not getting great bonding between the extruded tubing and the overmolding. We're communicating with Celanese (formerly Dupont) but hoping the someone on here has 1st hand experience.
We do peel testing as a indicator to check the end point of the overmolded section, and the results are not nearly as consistent as we would like. Currently in the early stages of a DOE to see if there's a best spot for our specific application, but advice is appreciated.
[ul]
[li]We use a pretty harsh chemical etch to prep the surface of the extrusion, but that has shown improvement in the bonding.[/li]
[li]Cross-section shows partial or incomplete bonds between the surfaces, I think these are the likely delamination initiation points[/li]
[li]Material is at or very near optimum dryness before molding[/li]
[li]Have not tried post molding Annealing cycle, cannot find literature[/li]
[/ul]
Before I can convince my management to redesign the tool or look at other materials, they (understandably) want to exhaust every possible process setting in trying to improve the performance of the ovemolded assembly.
Also any base material test methods that could be used to help me assess the performance without actually throwing it into our machine would be helpful.
Thanks Everyone!
Sorry for the cross-post thought maybe there might be more visibility here.
I'm looking for tips to improve over-molding of two very similar grades of Hytrel. I'm trying to improve the molding or other process parameters to get better bonding between extruded tubing of Hytrel 4056 and the Injection molded 3078, hopefully resulting in better component performance.
My application is every harsh with a steady state RPM of 2500-5000 for up to 3.25hrs. The good news is the component is intended for single use. I just need to make the part resilient enough to resist elongation-delamination-trib "death cycle". It just needs to last a bit longer than current state.
Currently the part is partially surviving ~1-2hrs, but with unacceptable elongation (post-delamination) resulting in abrasions w/unacceptable amounts of particulate. I believe that some amount of delamination and particulate is unavoidable, but maybe there are things I could do to improve its performance?
We're not getting great bonding between the extruded tubing and the overmolding. We're communicating with Celanese (formerly Dupont) but hoping the someone on here has 1st hand experience.
We do peel testing as a indicator to check the end point of the overmolded section, and the results are not nearly as consistent as we would like. Currently in the early stages of a DOE to see if there's a best spot for our specific application, but advice is appreciated.
[ul]
[li]We use a pretty harsh chemical etch to prep the surface of the extrusion, but that has shown improvement in the bonding.[/li]
[li]Cross-section shows partial or incomplete bonds between the surfaces, I think these are the likely delamination initiation points[/li]
[li]Material is at or very near optimum dryness before molding[/li]
[li]Have not tried post molding Annealing cycle, cannot find literature[/li]
[/ul]
Before I can convince my management to redesign the tool or look at other materials, they (understandably) want to exhaust every possible process setting in trying to improve the performance of the ovemolded assembly.
Also any base material test methods that could be used to help me assess the performance without actually throwing it into our machine would be helpful.
Thanks Everyone!
