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HDPE (3D Printing Material) – All You Need to Know

Picture of Melanie Griffin
by Melanie Griffin
Jun 10, 2019

HDPE (3D Printing Material) – All You Need to Know

HDPE is a type of plastic that is turning the 3D printing world towards a more sustainable future. It's a great recyclable filament, but it's not without its quirks.

HDPE & 3D Printing The Basics

HDPE can be recycled from plastic bottles into 3D printing filament.
HDPE can be recycled from plastic bottles into 3D printing filament. Source: Scientific Fabrication Laboratory

HDPE stands for high-density polyethylene, and though that name might not ring a bell, we guarantee that you know what we’re talking about. This is the recyclable plastic that holds your grocery store milk, your laundry detergent, your bottled soda, and millions of other common products across a wide variety of industries.

One of the reasons HDPE is so ubiquitous is its high strength-to-density ratio. As a thermoplastic polymer made from ethylene, it’s super strong yet light enough to float, which makes it useful in a huge variety of scenarios.

In addition to holding consumer products, it’s also frequently used for corrosion-resistant pipes, liquid-permeable membranes used in biology settings, and lumber made out of recycled plastic. 

This also highlights another plus of HDPE and why it’s gaining popularity as a 3D printing material: It’s easy to transform into new material through recycling. You can do your part to clean up the Earth by keeping recyclable plastics in rotation, and using HDPE as a 3D printing filament benefits you and the planet at the same time. 

To make this transformation, HDPE containers like plastic drinking bottles are shredded, then melted together and guided into a thin string-like shape. This second step is kind of like making pasta noodles, and once the newly strung HDPE cools, it’s spun onto filament spools for your 3D printing use. 

HDPE & 3D Printing What to 3D Print

A boat 3D printed with melted milk jugs (HDPE).
A boat 3D printed with melted milk jugs (HDPE). Source: solidsmack.com

Its strength, low density, and non-toxicity make HDPE ideal for a wide range of 3D printed objects. Below are a few common application areas.

Objects that Float

Because HDPE’s density is low, it can be 3D printed into objects that retain their buoyancy even at large sizes. Add its ability to not absorb water, and you have a great excuse to make your own boat!

If you don’t want to go to the trouble of 3D printing a full-sized canoe, you can still take advantage of how well HDPE floats by using it to 3D print bath or pool toys – anything you want to take into the water without worrying that it will sink.

Complex Objects

Given that HDPE can be dissolved in limonene, you can use it as a filler material for geometrically complex objects. Immerse your entire print into a vat of limonene and save yourself the hassle of breaking off hard-to-reach supports.

Food Containers and Lids

Does anyone actually have a full set of matching Tupperware and lids? Make up for whatever storage solutions magically disappear by 3D printing your own. They’ll be non-toxic and won’t dissolve or absorb water, so they’re great for drink accessories like coasters and koozies too. Just be sure to hand wash them so they’ll stay as neat as when you first print them.

Medical Objects

This is more of an industrial use and best left to experts, but we want to mention it as an example of HDPE’s versatility as a 3D printing material because it’s changing the medical field for the better.

HDPE has proven to be a great material for medical containers for the same reasons it’s a good food container filament – it’s certified as non-toxic by the FDA and resistant to water absorption. But industrial medical supply makers have also been experimenting with making more invasive medical objects from it, such as replacements for lost pieces of bones. Its strength and lightness make it ideal for these kinds of medical needs, and its sustainability as a material drives down cost and opens up its accessibility. 

HDPE & 3D Printing Advantages

You can print your own milk jugs with HDPE!
You can print your own milk jugs with HDPE! Source: 3D_molier International / Turbosquid

3D printing with HDPE lets you take advantage of its best properties for your own projects: 

  • Watertight: One reason HDPE is used so much as a liquid container is that it’s not soluble in water. That characteristic translates into its 3D printing filament form, too, which makes it great container material. 
  • Lightweight yet strong: The composition of HDPE keeps it from “branching,” or splitting at the molecular level, and that’s where its high strength relative to its mass comes from. As a 3D printing material, HDPE gives you great support for extensive designs without weighing them down too much to work. 
  • Dissolvable: HDPE is dissolvable by limonene, which makes it ideal for 3D printing support material. If you have a design that requires a lot of overhanging details or gaps between sections, HDPE can be printed as temporary scaffolding to hold those sections as they’re printing. Once the object is done and cooled, dunk it in limonene and the HDPE will dissolve, leaving just your design in perfect shape. 
  • FDA approved: This filament is rated as food safe, which means it’s so non-toxic you can eat off it. The FDA’s approval also means it can be used to 3D print medical objects without worrying about the filament contaminating biological material.
  • Recyclable: HDPE’s most famous advantage is how easy it is to recycle. Making it into 3D printing filaments creates a new use for the millions of tons of waste humans produce when they use this type of plastic. Plus, when you use HDPE for 3D printing filament, you can recycle your unused filament and finished objects as well if you get tired of them. They’ll go towards new filament for someone else, containers for consumer goods, pipes to help get clean water to people, or any number of other helpful uses. 

HDPE & 3D Printing Disadvantages

HDPE 3D printing filament tends to shrink as it cools.
HDPE 3D printing filament tends to shrink as it cools. Source: MohG / SoliForum

3D printing with HDPE can be tricky if you don’t know how to adjust for its quirks. Here are its major issues:

  • Easy warping. HDPE has a reputation of being difficult to print with because of its tendency to warp while printing. That’s an unfortunate side effect of its low self-adhesion: Layers don’t stick to each other well. Without careful supervision of the printing process, this problem can knock a design out of whack.
  • Poor self-adhesion: HDPE’s low level of self-adhesion also affects your final objects printed with it. Since the layers don’t stay together as well as other 3D printing materials, like PLA or ABS, you may want to brush a layer of glue on the outer planes of your projects to give them extra hold. However, know that this step may affect the non-toxicity of HDPE. Think about what you’re using it for before you commit to any sort of extra finish on top of the filament. 
  • Shrinkage: As a 3D printing filament, HDPE also shrinks when it cools down, which can cause major usage issues with your final project if you’re not expecting it. Your best bet is to design and print a test object with HDPE, then measure the shrinkage and adjust your design upward accordingly. This will help you combat some of HDPE’s warping properties.

HDPE & 3D Printing 3D Printing with HDPE

3D printers that are compatible with ABS filament are also compatible with HDPE.
3D printers that are compatible with ABS filament are also compatible with HDPE. Source: Tiertime

The good news is that the basic method of 3D printing with HDPE is your standard FDM process. Unfortunately, it’s not considered a particularly easy material to print with.

You don’t need to buy a new rig to make sure you can 3D print with HDPE. But make sure the 3D printer you do have is compatible with ABS because, for the most part, those are the settings you’ll need for HDPE as well. Fortunately, ABS is one of the most common 3D printing filaments out there, so if you’re shopping for a machine, you won’t have any trouble finding one that will fit both its needs and HDPE’s.

High Nozzle Temperature

HDPE takes a slightly high temperature, between 230 and 260 °C, to flow consistently through an extruder. However, if you let it get too high, the material starts to put out a toxic smell. Be exact with your extruder temperature when using HDPE as a filament.

Heated Print Bed

Because it has self-adhesion and shrinkage issues when cooled, HDPE filament works best when printed on a heated bed. This keeps the material stable and warm enough to keep its shape throughout the printing process, and it also gives a bit more stickiness to your object’s foundation.

Limonene

This is strongly recommending if you’re going to be rocking any intricate designs that need support material to stay in shape while being printed. HDPE is great for that because it won’t dissolve for just any liquid. You don’t have to worry about wrecking your supports if you accidentally spill water on HDPE, for example. But limonene works like a dream to take away all traces of support when you’re ready for your design to stand alone.

HDPE & 3D Printing Where to Buy It

With a 3D printing filament extruder, you can make your own HDPE filament.
With a 3D printing filament extruder, you can make your own HDPE filament. Source: 3D Printing Media

Unfortunately, ready-to-go HDPE filament isn’t so easy to come by. Nevertheless, here are a few places you can try:

  • Filaments.ca ($25.92 per 1 kg) is based in Canada, so you may pay more to get this, but its quality is worth it. Plus, they don’t pull punches on the challenges of 3D printing with HDPE just to sell you something. Their website is definitely worth checking out.
  • Filaments.Directory lets you shop their HDPE ($42 per spool) and ship it from their store closest to you.
  • Yourself! The Filabot EX2 Filament Extruder ($2,699) lets you make your own HDPE with recycled plastic. You can even use failed HDPE prints to recycle them into improvements.

Feature image source: Re3D

License: The text of "HDPE (3D Printing Material) – All You Need to Know" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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