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Solutions To A Plastics Problem?

Solutions To A Plastics Problem?

(OP)
We use what is called a skidding system for moving heavy (100 ton range) transformers off of trailers and onto foundations in substations.
This is a similar concept but different design: http://www.enerpac.com/en/heavy-lifting-technology...
Ours is essentially 2 rails made from heavy I-beams. Each beam has a yoke with holes that pins go into, the pins go through the web and reinforcing plates of the beam to push against, and then cap channels ride on top of the beams with the load on top of them. Mounting points connect the yokes to the cap channels via large hydraulic cylinders. When activated they push or pull the cap channels along. The sliders are, with extensions, 18'6" long and have a 6" contact surface with the beam (roughly) so I'm figuring 110 psi at best case with 100 ton on it, sometimes they only fit in 8' of the slider however at which case we're looking more at 350 psi. The unit itself moves very slow, the rate of travel over the plastic is only maybe 2'- 2.5' a minute.

In the past we've used soap flakes as a lubricant but we lost access to those. So we changed to liquid soap by the barrel, but in summer the heat causes it to turn into more of a tacky glue than a lubricant, so we went to grease on top to lower the coefficient of friction. Due to environmental concerns the client would prefer we move to a non-grease system, and due to messy clothes we'd prefer that too, but other lubricants aren't much of an option as this system performs in direct sun on 100 degree days and covered in snow in -15 degree days all depending on when things have to be done. So far none of the lubricants have worked as well in all situations.

So we decided to hire a plastics company to choose the proper plastic for us so we could line the top of the beams. I don't have any paperwork as this was a few years ago, and the plastics company has since went out of business, but we finally got the system downed long enough to switch over to the mounted plastic. The plastic is grey, supposedly has lubricants embedded into it, and seems to be very dense, but I was told it was not UHMW as that was brought up in a meeting and they suggested this instead. Based on that I have no clue what it is. They said it was used as turntable wear pads for heavy equipment like draglines but I find that hard to believe given how hard it's moving for us.

What I do know is that when we started doing a test slide with only 50,000 lbs, the whole system began to chatter wildly. The test load was bouncing slightly. I also know that if the plastic gets wet, instead of becoming slippery it turns more into a tacky surface. We tried lubricating the surface with silicone spray as that's "less messy" in the customers view, but it had no effect.

My questions are threefold:
1) Does anyone have an idea what plastic this is based on the little info I have?
2) Is there a different option we could be trying for lubrication on the plastic that might work better than grease/silicone spray without being super messy that will work with the plastic instead of fighting it?
3) Is there a different plastic we could try given the loading that will perform in all temperatures without the need of grease (or without any lubricant?)?

RE: Solutions To A Plastics Problem?

Have you considered using Delrin? That's plastic with lube built into it. It isn't messy to the touch. Nothing gets on your fingers. It machines beautifully and is commonly had.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Solutions To A Plastics Problem?

(OP)
This might actually might be Delrin, that name sounds very familiar.

RE: Solutions To A Plastics Problem?

How did you lose access to soap flakes? You should be able to order from a variety of sources, for about US $5 to $7 per lb.

These guys sell up to 400 lbs. in bulk:

http://www.soapgoods.com/Soap-Flakes-p-1449.html

A few bars of soap and a cheese grater would seem to do in a pinch as well?

As far as the plastics go, you should probably try virgin teflon; it should work ok at the bearing pressure you quote. But any plastic is going to abrade pretty rapidly with those loads and what I imagine is a fairly dusty/muddy environment. I'd think soap flakes with whatever your gray material is would be a pretty darn good lubricant based on what you've said. Any way to incorporate rolling element bearings, or even just steel rollers?

RE: Solutions To A Plastics Problem?

(OP)
I should clarify, it's not just access to soap flakes that we lost, it's access to "good" soap flakes. We've bought bulk like you suggest but they just don't work the same as the old Ivory flakes we used to get. Something in what they're using to make the soap causes them to ball up and not lubricate quite the same. They work great in winter, but for some reason not so well in summer, to me I'd think it'd be the opposite as they get softer and more-readily spread in summer, but what do I know. We used to get, before flakes, Ivory soap beads and I guess these things were the cats pajamas but they stopped making them and made us switch to flakes. Then they stopped selling flakes (which also ticked off a lot of rock polishers, as many were using ivory flakes to clean the rocks and their drums for rock tumbling).

A few bars of soap and a cheese grater would be a mess, we need to lubricate, at times, several hundred feet of track. ;)

I thought about rollers but the problem there is height. Every little bit we add is more height that we have to jack these loads up into the air. In some situations that's a big problem since we're restricted by overhead lines or structures in the substations.

Teflon I think would work great but the abrasion is definitely a concern, as is cost. What we're currently using is 3/4" thick and I'm seeing prices of $300/sqft. We'd be looking at roughly 60-80 sq ft to cover the kit, so $24,000. For a material that *might* work and *might* last. Hence my fear.

RE: Solutions To A Plastics Problem?

Test 5' of it right in the middle of your current track... if it holds up to abuse, you have your new material. If it doesn't you've only lost a few hundred $s.

I would also think a boatload of Ivory bar soap in an industrial grinder would provide soap beads out the wazoo.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Solutions To A Plastics Problem?

(OP)
Can't get away with just 5'. Due to the length of the kit just to support the test weight I'd need something like 40' to verify motion, beam to beam transfer, etc. Which has me wondering why it was put on the beams to begin with rather than the bottom of the slider pieces themselves. several hundred feet >> 40 feet. Maybe I'll try decking out just the main units that way, then I'd only need to test 24' or so.

RE: Solutions To A Plastics Problem?

Sorry, but I was thinking teflon pads under the machine, not coating the rails. And yes, any plastic is going to have a fairly short life due to abrasion.

Does your gray plastic have a mottled, silvery appearance? Might be MDS-filled nylon. Spraying graphite or MDS spray on the rails might help keep stiction down, but I'm not a fan of the stuff.

RE: Solutions To A Plastics Problem?

(OP)
A-doy. Should have done that from the get-go. My bad.

This is a closeup of the plastic.


This is the plastic stacked above the parts that actually slide on the plastic.


These are a small assortment of the beams that the plastic gets bolted too.

RE: Solutions To A Plastics Problem?

Man, sure seems like roller bearings or recessed wheels are the way to go here. Certainly no thicker than the plastic already being added, if done correctly.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Solutions To A Plastics Problem?

(OP)
Might seem that way, but once you see how the jobsites are and how fast those would get dicked up with debris just from the airspaces you'd see that's a bad idea. The nice part of sliding is that its surface to surface so there's not any room for anything larger than a flake of rust to really get under the kit. With rollers we'd have to worry about gravel, mud, cement, and other stuff. These are used in some pretty messy job sites outdoors.

RE: Solutions To A Plastics Problem?

UHMWPE is a better bet. It is tougher than Delrin and much tougher than Teflon.

RE: Solutions To A Plastics Problem?

(OP)
When I see 'UHMW' listed, is that the same as UHMWPE and it's just shortened or are they 2 distinct products? We use UHMW a lot around here for crane boom slides and other things.

RE: Solutions To A Plastics Problem?

Adalius,

Didn't you ask these same questions in 2013 ( see thread404-357260: Grease Alternative .) . Were the answers then not adequate?
I am presuming that the Oakey Duck Butter is the stuff that is turning to sticky glue.
B.E.

You are judged not by what you know, but by what you can do.

RE: Solutions To A Plastics Problem?

Interesting how so many of the answers back then are the same now... from grinding soap bars to bearings and air...

Considering the problem (and suggested solutions) hasn't changed in 3.5 years, I'm less inclined to spent more time on this.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Solutions To A Plastics Problem?

(OP)
Jeebus. I guess I forgot I had asked this back then. Guess I'll go review that thread too.

RE: Solutions To A Plastics Problem?

Well...the main difference of Ivory to other soaps is what? It floats. It does so because the manufacturing process entrains air into the the soap bars, i.e. it becomes something of a foamed soap. Perhaps those air bubbles are helping your lubrication problem? So, try stuffing ivory soap bars through a cheese grater like this one (below), and see if you get the results you want. Or, try other methods of generating a foamed soap/grease (put the duck butter in a blender?).

https://www.amazon.com/SLC-Vegetable-Interchanging...

or if you don't want to get tired arms, this one:

https://www.webstaurantstore.com/light-duty-stainl...

Or, contact me and for the low low price of $15 per pound, I will manufacture grated ivory soap flakes for you and ship them to your job site.

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