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LIL OT: Urethane Lined Tumbler Tank....How do they line them?

david n

david n

Diamond
Joined
Apr 13, 2007
Location
Pillager, MN
Kinda curious...May help on a project I'm workin' on.....So rectangular tank tumblers......How do they line them? Place a core in the tank and then just pour the urethane in the void? Do they then put them under vacuum to eliminate air pockets and bubbles? Oven cure? And what kinda surface prep for best adherence? Just clean metal or maybe sandblasted first? Tryin' to get edjicated here....................
 
I don't know how it's done at the factory, but I've seen at least one field relining done at a local truck bed liner spray shop.
 
With the right viscosity of the coating material, you could line a rectangular tank using rotational molding or slush molding. The resin can be liquid or powder. Never heard of doing that with urethane, just speaking generally. Liquid resin (PVC aka Plastisol is done this way) would cure as the solvent is cooked away. Powdered resin would melt and fuse. PE is the most common resin molded with way. A thermoset would also be possible.

Jeff
 
Takin' from Mfgr web site..............

"Tanks are 1/2"-5/8" lined with high quality Hot Poured, Uniroyal Polyurethane, that is Oven Cured."
 
So, if HDPE would work, I can answer your questions vis-a-vis rotomolding:

Place a core in the tank and then just pour the urethane in the void? No core needed, temporary lid for molding.

Do they then put them under vacuum to eliminate air pockets and bubbles? Also not needed for a smooth finish, usually 1/8 to 1/4" thick, but thicker no problem, out to maybe 3/4".

Oven cure? Yes

And what kinda surface prep for best adherence? Just clean metal or maybe sandblasted first? Certainly sandblasted would work but not needed.

Another option with a rectangular tank would be just using sheet HMWPE and plastic welding the seams. Easy to replace that way if it wears out eventually.
 
Exactly zero, just an idea based upon looking at the manufacturer's website and assuming this might be a one-off where investing in tooling may be less attractive. "Hot Poured, Uniroyal Polyurethane, that is Oven Cured" could be done with a core, as the OP suggested, or with slush or rotational molding.

Jeff
 
No centifugal process with a rectangular tank, duhhhhh. Plus then, what about the bottom?. The oven cured thing is new to me. My experience with solid urethane is limited to urethane filled tires ( No, it's not "foam") and playing with a "Superball" as a kid. I supppose that it might cure from heat as well as a catalyst. Maybe contact the successor to Uniroyal?
 
They remove the old liner (this can be done by hand or in an oven) then sandblast it clean. Don't try to burn one out (don't ask me how I know). Then they put in a mold and fill the void with liquid urethane. 80 durometer is normal. An upgrade is hot poured/hot cured. Upgraded liners can be up to 90 durometer. Relining is expensive. Spray on truck bed liners don't work as you can see by the $1,700 missing from my billfold.

Rick Seeman
www.vibratoryfinishing.com
 
Shop I last worked in got a 5' diamater tumbler cheap because when they rebuilt the motor they screwed up the liner when baking the motor, integeral motor. My cheap employer then manually removed the old liner and took it to a local shop that did urethane bed liners. They sprayed in a nice 1/4" thick liner than lasted for 5 years before I left. It had worn a little but other than that was perfect and we used the shit out of it including larger, rough steel parts with heavy burrs using landscape rock for media. Looked like it would last another 20 years at least.

Watch out for the spray on bed liner shops using cheap urethane. Exactly what is used can make all the difference! This comming from a customer who did small run cast urethane parts, and his brother did bed liners. I think the difference is the base resin, urea vs something else or something like that.
 
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