UHMW Black vs White (Recycled vs Virgin)

[MikeInOr]

I want to make some slides for a table top to ride back and forth on. The table will be cranked back and forth (by hand) with a screw. I just need the top to move, not move fast nor move frequently. I am thinking about making the slides out of Unistrut and UHMW. Assuming that Black UHMW is the cheaper recycled UHMW is there any advantage to virgin (white) UHMW plastic over the cheaper recycled (Black) UHMW plastic in this slow moving application?

 

[matthewsx]

Should be the same composition. We use lots of it here at work for similar applications and can't see any advantage of one over the other.

John

 

[MikeInOr]

Should be the same composition. We use lots of it here at work for similar applications and can't see any advantage of one over the other.

John

Great! Thank you!

Is there any advantage to putting a lube on the Steel/UHMW contact points? Something like PTFE or Silicone? Or is UHMW slick enough it won't really matter?

 

[C-Bag]

UHMW is slick by itself. The best is the gray UHMW as it has some kind of lube in it. Personally I’d use something like FluidFilm because it’s not petroleum based.

 

[C-Bag]

UHMW is some wonderful stuff. We used it a lot in fruit and veg packing and thats where I became familiar with it. i never saw black UHMW, so never heard it was recycled. White UHMW was used for butcher blocks too. I understood it the white UHMW was used and only black Delrin so we could quickly tell them apart by color.

We were making this new plastic link belt for packing because it could do S shapes and bends that regular belt conveyors couldn’t do. But over time they’d stick if they didn’t have some kind of lube like water. That’s where they came up with the gray stuff. That worked better but without water it would eventually stick too. Looking back with what I‘ve learned here about stiction I’ll bet that was the main problem. As it slides on itself it’s slick as glass.

Before my brother moved back east he was getting rid of everything and he had a 4’x4’x1” thick sheet of the gray UHMW they had picked up when they remodeled the high school bathrooms in Stockton. The school used it as stall dividers! My brother just picked up the one remnant not knowing even what UHMW was much less this was special. I got that piece and several smaller pieces and just so happened used a chunk today as a guide link on the Z axis of the new DRO I’m putting on my drill mill. Love working with this stuff.

 

[RandyM]

With use, white will show dirt and grease, if that is a concern.

 

[C-Bag]

white will show dirt and grease,

True, I think that’s why it’s used in the food industry because you can see the dirt. It’s usually easy to clean but some grease seems to stain. I always thought the stuff was impervious to stuff like chlorine/water as it’s used in pre wash when fruit comes in from the fields and the huge UHMW chain guides would be swimming in that and dirt 24/7 lasting 5x longer than steel keystock!

That was until we installed a radicchio line. Somehow the mix chlorine/water and radicchio schmooz would turn UHMW to granular pellets in a matter of weeks. Ate the whole dump line in only one season. I think that stuff would eat through stainless, and people eat that? Not me.