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I need to fasten pieces of HDPE together but I’ve heard gluing HDPE is difficult (after all, glue comes in HDPE containers, and the glue doesn’t get stuck in the bottle).

Using mechanical fasteners make sense, but can these fastening systems be made of HDPE as well?

I have in mind recycling HDPE, and need to, say, fix plates together to form a small box (approximately shoebox sized).

If I use mechanical fasteners made of metal, the end product won’t be easily recyclable for another go-round at the end of the product’s expected usable life. The metal pieces would have to be separated in some way.

If the fastening system is made of HDPE as well, the whole thing could go into a shredder for another recycling cycle.

I don’t expect there will be much tension at these joints, but there might a little, perhaps.

In any case, if screws were made of HDPE, and the receiving plastic pieces were predrilled and machined with matching threads, would this work?

Anyone have any experience with HDPE screws and threading in HDPE, and using HDPE for mechanical fastening?

Thanks.

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    $\begingroup$ How are the glue bottles sealed? $\endgroup$
    – Solar Mike
    Jun 13, 2021 at 18:40
  • $\begingroup$ Generally, I think glue bottles have screw on tops, and a sliding mechanism to allow access to the glue. Think Elmer’s glue from grade school. But, a screw on top, made of HDPE, so at least much works ... $\endgroup$
    – Bruce Simonson
    Jun 13, 2021 at 19:00
  • $\begingroup$ How about the other end of the bottle????? The screw cap was too blindingly obvious. $\endgroup$
    – Solar Mike
    Jun 13, 2021 at 19:02
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    $\begingroup$ Please clearly indicate your application. At this time, your description is quite confusing and does not make sense, if HDPE stands for High-Density Polyethylene, a type of plastic. $\endgroup$
    – r13
    Jun 13, 2021 at 19:15
  • $\begingroup$ I've reread this a few times and I think when OP says "HDPE mechanical fasteners", he actually means "mechanical fasteners for HDPE". All the more confusing because later OP uses "metal mechanical fasteners" to refer to fasteners made of metal, not for metal. Inconsistent, conflicting verbiage. $\endgroup$
    – DKNguyen
    Jun 13, 2021 at 19:37

3 Answers 3

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Two pieces HDPE can be welded together with heat. You can use filler rod for this but it is also possible to do this with just heat. Additionally you can ultrasonic weld HDPE but this itself is a bit tricky in my experience. Any one of these should be sufficient for your application.

You can obviously try to glue HDPE, its possible. But the glue itself degrades the recyclability of your product. Screws work offcourse as would rivetting. I would use the later as they are readily available.

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    $\begingroup$ You can consider using rods and heat welding them at the ends kind of like rivets. Simpler than machining screws. Similar to heat staking (or you could just outright try heat staking). $\endgroup$
    – DKNguyen
    Jun 14, 2021 at 14:26
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A google query “hdpe book binder screw sets” revealed a product made of hdpe which consists of a screw and matching sleeve. This item shows that hdpe can be used as a screw or bolt, with tapped threads in hdpe as well.

Finding a product which has appropriate dimensions for my project will take additional work, but it’s good to see that hdpe can be used for screws or bolts, and tapped threads and possibly nuts, to hold hdpe items together. This mechanical solution will not require glues, solvents, or hot welding.

Rivets made of hdpe probably also exist, and might also work too.

Thanks. Onward!

hdpe binder post

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You should research things yourself instead of "hearing" that things don't work.

Bonding Low & High Density Polyethylene with Industrial Adhesives.

Superglue (CA glue)

Cyanoacrylates Cyanoacrylate adhesives can be used along with primer Permabond POP. Cyanacrylates set almost instantly and provide good adhesion to HDPE provided the surface is pre-treated with Permabond POP primer. The bonds have good resistance to non-polar solvents but do not fair as well with polar solvents. Standard ethyl cyanoacrylates are brittle and do not have good impact resistance. If impact resistance is needed contact Permabond about Flexible Cyanoacrylates.

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  • $\begingroup$ Sorry for the confusion. I wish to bond 1/4” plates of HDPE in a 90 degree corner. I have researched the net, and have found superglue and some epoxy solutions, but all of these seem to have some negative reports. (There is even a hack that suggests using baking soda with super glue.) My question is more general: does anyone have experience making HDPE screws with matching threads in HDPE? Or perhaps even making matching nuts and bolts from HDPE, and using these as fasteners? $\endgroup$
    – Bruce Simonson
    Jun 13, 2021 at 22:42

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