UHMW

[CatHead]

what does UHMW stand for?

 

[HuFlungDung]

Ultra High Molecular Weight!

Make sure you have a back support on when you lift this stuff!

 

[snowman]

Sorta like HDPE

Ultra high molecular weight

High density polyethylene

Behave very similar, UHMW is a bit more resistant to chemical attack and a little better with friction...also more expensive.

-Jacob

 

[TimH]

Ususally refered to as "Poor man's Teflon" Most of the same characteristics lower heat tolerance, a little harder to machine ( I think at least compared to Teflon)

 

[Steve Stube]

The difference between High Density Polyethylene (HDPE) and Ultra High Molecular Weight Polyethylene (UHMWPE) is the length of the molecule or chain. HDPE might be 100,000 units in length while the UHMWPE starts with a chain length of one million carbon and hydrogen groups. To say UHMW without specifying the particular polymer (such as Polyethylene) is rather meaningless.

 

[andy pullen]

We used UHMW exclusively for the bearings on submarine periscope masts. With a sharp piece of HSS you can really fly through it. We would buy the stuff and set it on the shelf for a year before actually cutting it. The stuff is inherently unstable when it's "new" from the factory. After it's aged for awhile; it's a dream to work with.

I made a bearing for the water plant here at work about 2 years ago out of UHMW and it was inspected by the millwright that installed it a month or so ago and it's still as good as the day I made it. It was eating the nylon bearings about every 6 months.

Andy Pullen

 

[Doozer]

I have made some stuff with UHMW PE. Some spinning stuff, some sliding stuff. I am in a plant, and I can see the results of it in use, and I can say, IT DOES NOT WEAR, at least not measurably so. One application was on our siesmic test bench. The 16" rod hydraulic cylinder is mounted horizontally. Oil anylasis showed some bronze (from the rod bushing). The weight of the ram was so much, it was wearing the bushung. A clevis is usually mounted to the ram. We built a sliding plate of UHMW PE under the clevis, to take the weight off the rod. Future oil anaylasis showed that it worked (no more bronze). The sliding plate still looks new, years later. --Doozer

 

[johnoder]

Great stuff. I have used it where it got overloaded in compression - it just moved out of the way (deformed pin bore). It is also extremely heat sensitive. Too close with a cutting torch and it ran like melted wax. This was one of my more crappy designs the customer (Citgo) had to scrap out in place

John

 

[Billy Boy]

Anyone kno how this stuff is formed in the factory?

I assume that it is extruded using some sort of process.

Why do you have to let it sit?

B

 

[junior machinist]

I used some and needed black. I found out later that there is 2 kinds. 1 regular and 1 is UV proof. So if it is something for outside keep that in mind.

 

[andy pullen]

Uhmw needs to sit for awhile to "age". When you use new material, it's very unstable dimensionally. You take a cut and cut to size and tomorrow it will be a different size. I don't know if it's solvents or what. That's just been my experience. And, I'm sure many others, too.

Andy Pullen

 

[MrWhoopee]

Uhmw needs to sit for awhile to "age". When you use new material, it's very unstable dimensionally. You take a cut and cut to size and tomorrow it will be a different size. I don't know if it's solvents or what. That's just been my experience. And, I'm sure many others, too.

Andy Pullen

I wasn't aware that aging would improve this characteristic. In my experience, "precision" and "UHMW PE" are mutually exclusive terms.