Has anyone played around with HDPE?

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markz   100 GW

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Has anyone played around with HDPE?

Post by markz » Jan 30 2019 1:36pm

I saw a video on a youtuber making a mallet out of milk jugs, seems solid enough. I went to go find what else was made of HDPE

https://www.plasticsmakeitpossible.com/ ... o-popular/
Why so popular? Here’s why:

It’s lightweight yet super-strong. That’s why an HDPE milk jug that weighs 2 ounces can carry a gallon of milk. And why many carmakers use HDPE fuel tanks—lighter weight car parts can help increase fuel efficiency.
It’s impact resistant. Drop the toy truck down the stairs and it bounces.
It’s long lasting and weather resistant, so that plastic lumber deck in the backyard can entertain generations of families.
It resists mold, mildew, rotting, and insects, so it’s great for underground pipes used to deliver water.
And it’s easily molded into nearly any shape, providing one of the primary benefits of most plastics: malleability.
Seems perfect to make a battery box out of. Milk crates are made out of HDPE, so I figure I go on the hunt for some and give it a whirl.

No oven to help melt it, but careful use of blowtorch and some steel plate may work. I also have a thrift store clothing iron that may help.

Of course anytime I go a searching for what others have done, it all comes back as using the bins for storage shelves, tables and what not. When I find something on "Melting" its someone burning the milk crate.

The milk jug videos shows them cutting the jugs up into flakes, onto a tray, into a toaster oven or regular oven until the right consistency

https://www.youtube.com/watch?v=PBRoAoMNYck

dustNbone   10 kW

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Re: Has anyone played around with HDPE?

Post by dustNbone » Jan 30 2019 2:01pm

It's tough stuff for sure.

I had a 4L jug of milk fall off my rack a couple days ago at about 20MPH (I kinda dropped the ball strapping it down with a 10kg bag of cat food, almost made it home lol).

Luckily it landed bottom down, and to my surprise it didn't even put a pinhole in it.

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amberwolf   100 GW

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Re: Has anyone played around with HDPE?

Post by amberwolf » Jan 30 2019 2:47pm

It has a fairly low melting point, not far above the temperatures it gets here in summer on the hottest few days of the year, late June usually. The temperatures on the roads and sidewalks can easily be above it's melting point even on other summer days, so you may see deformed and shrunken HDPE bottles and containers laying around from that. (never seen a puddle of one yet; doesn't stay hot enough long enough).

So you can just use a doubleboiler. Then there's no risk of fire from igniting vapors. ;)

You might also look up Friendly Plastic; comes in pellets designed specifically for this use.

The main problem is you can't glue it together; you have to form it directly into whatever you want it to be (you might be able to make a block and machine it).


Some posts about melting HDPE
https://endless-sphere.com/forums/searc ... mit=Search

markz   100 GW

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Re: Has anyone played around with HDPE?

Post by markz » Jan 30 2019 8:09pm

Another idea was Lowes is selling their big buckets for $2.50, those gotta be HDPE as well, be easier to work with then stealing milk crates.

Cut off the bottom, cut off the ridges, do one cut and spread it out, warming it up to flatten it. Easier to do then trying to melt stolen milk crates. For a good edge, I will have to build a clamping mold.
lowes bucket.jpg

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Dauntless   100 GW

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Re: Has anyone played around with HDPE?

Post by Dauntless » Jan 30 2019 11:04pm

No, I haven't played around with it, I studied it in school. It does not have a low melting temperature, it has a low FORMING temperature. Which makes it friendly in some ways. Such as boiling it in water to soften it up. Much like metalsmithing, you can work pieces together when you get them hot enough. You compression mold with it, that requires some planning. But I think it was Toyota had HDPE body and interior parts sagging on them recently.

You can also plastic weld.

When you find the number 2 or 4 on the bottom that is high density and low density. Think plastic grocery bags tend to be polyethylene. Oil at the auto parts store, many juices, there's lots of it out there. Mattel toys calls their variant of polyethlene 'Tuff Stuff.' Let's not forget Tupperware.

Then there is uhmw. Ultra high molecular weight polyethlene. Strong enough to be used for surfaces in assembly line equipment, etc., It's the 3rd slipperiest surface know to man. In a lot of ways replacing sheet metal with maybe 5 times the thickness in uhmw can be stronger. It is certainly impact and abrasion resistant.
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marty   10 MW

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Re: Has anyone played around with HDPE?

Post by marty » Jan 31 2019 3:08pm

Heat gun and leather gloves. Shape the plastic to what ever ya dreaming of.
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