UHMW Alternative

So a customer of mine is designing and planning a small production run of various parts of a snowmobile for high performance hill climbing.The list is long of what he is changing,but I am stuck on this one part.
Let me first disclose I do not know anything about snowmobiles,just the machinist and sometimes help with design.
So this part is 2 wheels that help keep the track in place
His design calls for a wheel and more importantly a bearing of certain size that will fit in his design.
Hence,not a store bought item.
I know this vague,but so is my understanding of the whole thing.
My question is,what would be a good substitute for material instead of UHMW?
Probably someone out there knows what that wheels actually does and the requirements it must meet ?
The bottom line it is a bitch to machine and especially the bore to hold the bearing when he is asking for like 100 parts
He is open for alternatives in material as long as it meets the criteria for what it needs to do.
Someone please be an Einstein,I hate this part

UHMW is desirable for a number of reasons: it's quite tough, self-lubricating, and under the right conditions it will out-wear hardened steel parts. I can't say that I know the part you're talking about well enough to suggest an alternative, but I can say that UHMW (where its use is really warranted) is not something that can be casually substituted. You might be out of luck

yeah,that crossed my mind.Guess labor goes up and time to get some HSS tools out of hiding.
It is doable,but time consuming.Love the stringy mess.

You talk of bearing bore tolerances, .............what holds the bearing in the bore?

What material does the wheel run against? a rubber track, or something metal? If rubber, try aluminum and have him test it.
Where does this run, only in snow or all season?
UHMW is notorious for changing size, I doubt the bore will stay a press fit for a bearing.

You might look at acetal. Much more friendly to machine than uhmw

Tolerance on a bearing bore in UHMW?

The bore could be a mile small and you could
still press the bearing in.

Just thinking out loud here. I'm assuming this is an idler of some sort?
I wouldn't trust a bearing in UHMW. If it was me, just going by
your description, I'd probably use an aluminum hub to hold the bearings.

UHMW SUCKS!!!!! Its like machining bubble gum.
My personal philosophy on life. If it can be made
out of Delrin, make it out of Delrin. All parts should
be made out of Delrin, and if that isn't strong enough,
then onto 2024 or 7075 (6061 if you must). If it still
needs to be stronger, then it should be made from 303,
stronger than that and it should be made from 17-4..

I'd be a horrible materials engineer.

uhmw is the poor man's teflon . teflon is 10x the cost , and equally shitty to machine . maybe nylatron
could be an alternate.

one thing i've learned over the years is not to make other people's decisions . use what is in their design
and specs...let them have that . if you spec something that doesn't work out, it becomes your fuckup and
you lose . let the engineers fail....it's their risk , not the machinist's.

light press fit and retaining ring for bearing

Aluminum is a no go because I was told it would ice up

yes,the wheels g against the rubber track

Delrin too soft,,,but I love machining Delrin

Aluminum hub would be killer,but I would have to figure out how to mount a "tire" of some sort that comes in contact with the track.

Hence,probably have to figure out the best methods to get this part made from UHMW.

It is what the industry uses,,but they look casted or something

Everything else will be expensive

nylatron
delrin
rulon
kel f

I think only delrin is useful, only twice the price!

jrmach said:

Aluminum hub would be killer,but I would have to figure out how to mount a "tire" of some sort that comes in contact with the track.

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Google "pulley lagging".

tnmgcarbide said:

one thing i've learned over the years is not to make other people's decisions . use what is in their design
and specs...let them have that . if you spec something that doesn't work out, it becomes your fuckup and
you lose . let the engineers fail....it's their risk , not the machinist's.

Click to expand...

That's the sad reality, isn't it? No good deed goes unpunished. Transfer of liability is a big deal.

Another example: Bags get jammed up on a running conveyor at the airport? Don't try to be helpful. The second a guy tries to clear the jam, stop the conveyor or tell someone about it everything that happens afterwards is automatically his fault. Bags didn't make it on the plane before it left? Your fault. Someone files a damage claim afterwards and you were seen on camera trying to be "helpful"? Your fault. Conveyor didn't restart afterwards because you forgot to go to the controller and push up up, down down, left, right, left, right, B, A, Start? Your fault. Some guy gets cranky because he has to turn off his phone, get off his chair, climb up into the catwalk and fix a jam that already cleared itself while you were telling him about it? That one's *especially* your fault!

If it's not explicitly your problem to deal with then stand back and let it burn.

Escalator step rollers have the bearing snap into the bore. Both ends of the bore are undersized. The portion of the bore where the bearing fits is a proper fit for the bearing. I presume the plastic roller is warmed up before pressing the bearing. The bearing is pushed through the tight end of the bore until it snaps into place. I don't know the plastic that is used nor do I know the dimensions of the bore. I think I have one laying around that I could send you. It would give a good example of how to fit and retain a bearing in a plastic wheel.

Follow the advice given earlier: Let the customer come up with the final design them make the parts to his print.

Oh shit, UHMW isn't hard to machine if you get good tooling and figure out how to use it. In fact is great to machine once you get there. What else can you run .05"+ chip loads with such ease? As far as the bearing bore I would think .003"+ press fit would be in order, just heat the rollers up to 120-140 degrees before dropping the bearing in. The bore is going to match the bearing soon anyway, ever hear of plastic deformation? UHMW has little resistance to it. I was wondering how the bearing would stay put but snap rings answer that question.

I think polyethylene/ UHMW is the best plastic for this application with its toughness, wear resistance, and price. Acetal is no substitute for polyethylene, there is no comparison in wear resistance or resistance to chipping, which I figure this application needs, but is great for dimensional stability. Nylon is the next best plastic to use, but much more expensive and will change size quite a bit as it absorbs water and drys out, more so if it's 6/6. When you pick the plastic to use keep in mind saying nylon, acetal, or UHMW is like saying aluminum or steel. Do you want 1018, S7, or D2 that's been heat treated? That is how much difference there is when you start modifying the base resin. Also if you get UHMW with recycled content it's my experience that you can get anything that melts and mixes with polyethylene so beware. For the parts I make I make sure it's all virgin so my tools don't wear.

If you're doing enough volume then you would injection mold them. 12 parts a minute, or more, while using half the resin at 1/5 the price or less that you pay for bar, with a simple 4 cavity mold.

uhmw is crap for an application like this. There are many injection molded parts already being made for the rear idlers and the bogeys. Aluminum is also popular, it wears against rubber so life is good. I would be careful putting to much time into reinventing this wheel as there are may aftermarket options already available unless you are going to production. He is probably going after the "big wheel" 7' or 8" rear idlers. they look cooler than the stock but don't offer more than bling. do a google search, lots of people already doing such foolishness.

After rereading your post I would be choosing aluminum for the rear idlers. you can do cool shapes and it holds bearings well. people that buy this stuff want the bling. curious as to why he didn't come to you with a complete plan.

I ride in the mountains as often as i can, over 300 miles so far this year.

jrmach said:

Aluminum hub would be killer,but I would have to figure out how to mount a "tire" of some sort that comes in contact with the track.

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There are quite a few places which will cast urethane tires on metal parts. Also bumpers, recoil pads, contact surfaces, etc. For 100 parts, you might even learn how to do it in-house. Make sure your urethane supplier understands the usage and helps you pick an appropriate formulation (there are hundreds, no, thousands of urethane compounds on the market).

seiner said:

uhmw is crap for an application like this. There are many injection molded parts already being made for the rear idlers and the bogeys. Aluminum is also popular, it wears against rubber so life is good. I would be careful putting to much time into reinventing this wheel as there are may aftermarket options already available unless you are going to production. He is probably going after the "big wheel" 7' or 8" rear idlers. they look cooler than the stock but don't offer more than bling. do a google search, lots of people already doing such foolishness.

After rereading your post I would be choosing aluminum for the rear idlers. you can do cool shapes and it holds bearings well. people that buy this stuff want the bling. curious as to why he didn't come to you with a complete plan.

I ride in the mountains as often as i can, over 300 miles so far this year.

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I have worked with this guy doing custom motorcycles,Race boats as in K-Boats,and now snow mobiles.We have a great work relationship.So I try to help satisfy his needs when asked.As far as riding goes I have zero miles but he has done it since the age of about 3.We rolled out a partial package of what he is trying to achieve about 3 weeks ago.Top ranked hill climber in the World demo it and gave the thumbs up.Injection molding in the long run has been a though,but not yet.Not re-inventing the wheel,just need the bearing size and wheel size to fit to his scheme of things.

aluminum doesn't need a tire to run on a track, it's better without.
he's building for a race called hillclimb, the most well known is the Jackson hill hillclimb. youtube has some great videos of it. COMPLETELY different from mountain riding like I do. Although a good hillclimber will probably excel in the mountains I will fail badly on their track.

some pictures from this winter
My daughter on her 800 summit 154
my 850 summit 165 in a tree well 11' feet deep
sunset looking north over Thompson Pass

jrmach said:

I have worked with this guy doing custom motorcycles,Race boats as in K-Boats,and now snow mobiles.We have a great work relationship.So I try to help satisfy his needs when asked.As far as riding goes I have zero miles but he has done it since the age of about 3.We rolled out a partial package of what he is trying to achieve about 3 weeks ago.Top ranked hill climber in the World demo it and gave the thumbs up.Injection molding in the long run has been a though,but not yet.Not re-inventing the wheel,just need the bearing size and wheel size to fit to his scheme of things.

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I was under the impression that uhmw cannot be injection moulded anyway?

gregormarwick said:

I was under the impression that uhmw cannot be injection moulded anyway?

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I have never heard of anyone successfully injection molding uhmw.