Hello all.
I am looking to implement a polymer insert in a load bearing hook in an effort to address corrosion being worsened by fretting in the interface. The hook is constructed of stainless for stength and corrosion resistance in a submerged marine environment. The passivation layer on the stainless holds up well on non-stressed points, the problem only lies within the hook which interfaces with a glass-filled nylon covered shoulder bolt. I attached a REAL rough 2-second drawing of what the insert may look like just to help with the visualization.
I am hoping a small polymer insert will be a low cost solution by reducing friction and eliminating oxidized metal from the contact surfaces, which promotes the vicious circle of corrosion. The key properties of of the insert would be its ability to withhold the load without cracking (two separate products experience loads of 350lbs and 2500 lbs respectively), not succumb to deforming or cradling the load pin (operation includes freeing the pin by releasing the hook) and be able to stay in place (looking to use a high grade adhesive if possible).
Unfortunately I do not have as much design experience with engineering grade plastics. I have worked with Delrin, but something in my intuition tells me it is too soft and will deform. I have no hard evidence to back this up, but I am aware of much harder polymers which would seem to work better as long cost doesn’t get too prohibitive. A quick material property search with Delrin as the baseline (85 Rockwell ‘M’, Compressive strength 18ksi) yielded many results with hardness level above 110 Hardness and 30ksi Strength. Results included: Ultem (PEI), Celazole (PBI), Torlon (PI), Ketron (PEEK) just to name a very select few that I have at least heard of before. I was hoping this forum could give me some insight to these and similar materials beyond just the hard data sheet numbers. Also I am aware that nylon based composites can be used as self lubricated load bearings and wear pads. However, mechanical properties show them acting closer to Delrin. Could this mean my initial reticence about Delrin was misplaced? My brain would tell me there also may be some adhesion problems if the wrong polymer is used.
I know this a somewhat long post, but I have seen such excellent results, both for myself and others from these forums. Hey, if someone needs some hydrodynamics help down the road, I may be able to return the favor ?
I am looking to implement a polymer insert in a load bearing hook in an effort to address corrosion being worsened by fretting in the interface. The hook is constructed of stainless for stength and corrosion resistance in a submerged marine environment. The passivation layer on the stainless holds up well on non-stressed points, the problem only lies within the hook which interfaces with a glass-filled nylon covered shoulder bolt. I attached a REAL rough 2-second drawing of what the insert may look like just to help with the visualization.
I am hoping a small polymer insert will be a low cost solution by reducing friction and eliminating oxidized metal from the contact surfaces, which promotes the vicious circle of corrosion. The key properties of of the insert would be its ability to withhold the load without cracking (two separate products experience loads of 350lbs and 2500 lbs respectively), not succumb to deforming or cradling the load pin (operation includes freeing the pin by releasing the hook) and be able to stay in place (looking to use a high grade adhesive if possible).
Unfortunately I do not have as much design experience with engineering grade plastics. I have worked with Delrin, but something in my intuition tells me it is too soft and will deform. I have no hard evidence to back this up, but I am aware of much harder polymers which would seem to work better as long cost doesn’t get too prohibitive. A quick material property search with Delrin as the baseline (85 Rockwell ‘M’, Compressive strength 18ksi) yielded many results with hardness level above 110 Hardness and 30ksi Strength. Results included: Ultem (PEI), Celazole (PBI), Torlon (PI), Ketron (PEEK) just to name a very select few that I have at least heard of before. I was hoping this forum could give me some insight to these and similar materials beyond just the hard data sheet numbers. Also I am aware that nylon based composites can be used as self lubricated load bearings and wear pads. However, mechanical properties show them acting closer to Delrin. Could this mean my initial reticence about Delrin was misplaced? My brain would tell me there also may be some adhesion problems if the wrong polymer is used.
I know this a somewhat long post, but I have seen such excellent results, both for myself and others from these forums. Hey, if someone needs some hydrodynamics help down the road, I may be able to return the favor ?