HDPE Rotary Hinge Pins
HDPE Rotary Hinge Pins
(OP)
I am trying to make a simple plastic crate where all four side walls will be connected to the bottom face via hinges that allow the walls to rotate to and away (think of the sides of a cube with no top falling down outward and vice versa).
The thing is these hinges need to be purely plastic (HDPE) and look like the hinges of this box cover where there is an extrusion/pin fitted inside a hole, allowing the cover to rotate.
Link
Should I be worried about friction since the pin and hole are both HDPE? Will this be a transition fit? Can't find tolerance charts for this type of arrangement.
The thing is these hinges need to be purely plastic (HDPE) and look like the hinges of this box cover where there is an extrusion/pin fitted inside a hole, allowing the cover to rotate.
Link
Should I be worried about friction since the pin and hole are both HDPE? Will this be a transition fit? Can't find tolerance charts for this type of arrangement.
RE: HDPE Rotary Hinge Pins
TTFN (ta ta for now)
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RE: HDPE Rotary Hinge Pins
Adding metals will introduce other manufacturing headaches haha.
RE: HDPE Rotary Hinge Pins
If you have the type of hinge where two parts actually rub together, then add a lubricant like UHMW silicone to reduce friction, sound and wear.
Chris DeArmitt PhD FRSC
President
Plastic materials consultant to the Fortune 100
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RE: HDPE Rotary Hinge Pins
RE: HDPE Rotary Hinge Pins
The plastic PP hinge idea is cool, but has the drawback of now you have one piece and a much larger mold. Would definitely put a dent in the budget. How are those made? Blow molded? Rotomolded?
As far as a plastic pin, dont mold a solid pin. It will likely be too thick and sink and not work well. Use a cored out design (see pic). The coring keeps the walls reasonable, the cost down, and may act to clean crud out of the joint. Part it on the ZX plane so the parting line is on the small flat on the side, and gate it on the pointy end so its strait and gate embrittlement is not at the head.
Rick Fischer
Principal Engineer
Argonne National Laboratory
RE: HDPE Rotary Hinge Pins
On two walls of the crate, I will have two pins on each side (four total) which interlock into corresponding slots (class LT2 transition fit to account for heat, tolerance). That way, the load that the crates will carry and the load from other crates stacking up on it can be transferred symmetrically. At least, that's how I imagine it would work.
Sure the compression stresses will be higher on the pins, but I can get a decent life out of the box before it goes the way of the dodo haha.
RE: HDPE Rotary Hinge Pins
I don't see the cored out design picture or a link to it. This is new information for me because right now, all my pins are solid and not cored out (I assume you mean slightly hollowed out).
RE: HDPE Rotary Hinge Pins
Not sure how big of a pin diameter you are looking at. Ive seen stuff with larger pins that were molded solid and they didnt work well.
Rick Fischer
Principal Engineer
Argonne National Laboratory
RE: HDPE Rotary Hinge Pins
Thanks for the picture. My pin is definitely not like that but a simple cylindrical solid extrusion formed with the crate with I believe a 1/8" diameter (too lazy to check now).
RE: HDPE Rotary Hinge Pins
and add a lubricant like UHMW silicone to reduce friction.
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