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I need to replace the lid of my water kettle and am searching for a filament, that is suitable for this purpose. The requirements are:

  1. Stable at 100°C (212°F)
  2. Resistant to steam/moisture
  3. Food-safe

Has anyone experimented with this or similar purposes?

Trish
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typo
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    You may need to provide some information about your printer's capabilities, or if you're hoping to use a specialist manufacturing service. – Sean Houlihane Jul 27 '18 at 11:52
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    Once you find a material with high-enough melting point, you might consider printing and then applying a waterproof, food-safe overcoat of some paint-like material. – Carl Witthoft Jul 27 '18 at 13:21

3 Answers3

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Referring to the table provided in 0scar's answer, the key challenge with high temperature materials is the gap between the glass transition temperature (bed temperature) and the extruder temperature.

Polycarbonate for example is listed as usable up to 121°C, printing on a bed at 80-120°C, but requiring an extruder temperature of 260-310°C. This extruder temperature is potentially going to challenge the mechanical, thermal and measurement properties of a printer.

In this application, you don't strictly require 100°C operation, so Nylon (80-95°C) and ABS (98°C) might be worth trying. Even if one side of the part is at this temperature, immersed in steam, the opposite side is exposed to air and convection cooling. Providing there is sufficient thermal insulation and internal rigidity, the upper shell of the part is likely to support it. However, if the inner face does start to flow it may take some time before a problem is apparent.

So long as the material is not soluble, absorbing moisture may not be a major issue.

When it comes to being food-safe, this is a huge can of worms, and you're really looking to investigate 'how much of a risk' rather than get a go/no-go answer.

Sean Houlihane
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    I agree -- there's a lot of plastics which aren't FDA "food-safe" but which you could chow down on regularly without any medical risk. – Carl Witthoft Jul 27 '18 at 13:22
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    @CarlWitthoft: the danger is not always the material; 3D prints often have tiny gaps between layers where microbes can live and grow. these pathogens can be hard to wash away and can leech into food stored in such prints. As the lid to a steaming teapot, it's not likely a concern as steam disinfects, but it's worth mentioning here... – dandavis Jul 27 '18 at 21:01
  • You don't adress the "food safe" issie: ABS and Nylon are not "food safe" AFAIK – Trish Jul 29 '18 at 20:30
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There are few materials that go up to that temperature and beyond.

A very nice generic overview is given by Simplify3d:

This figure shows an overview of many of the used materials in 3D printing enter image description here

When looking closely, and without pointing to specific brands (to avoid a commercial posting), your best chances for appropriate filaments for your application is to look at Nylon, Polycarbonate (do not consider Polypropylene; that is very difficult to print) or (not mentioned in the overview as they are more recent filaments) Co-Polyester polymers.

0scar
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I recommend PEEK if you are able to print around 400 °C.

From Wikipedia - Polyether ether ketone

Wikipedia's property chart

As requested in comments, here is the setup I use to print small PEEK parts:

  • Hyrel3D Engine, Standard Resolution (ESR): $2500 list
  • Hyrel3D MK1-450 print head for 1.75mm filaments between 300 °C and 450 °C: $450 list

Please note that larger parts will require (and all parts will benefit from) a heated build chamber.
Also note that annealing PEEK parts after printing (we use a circuit board reflow oven) recrystallizes (strengthens) the PEEK (and is recommended, but not required).

Here is one of our videos from 2015 showing the 410 °C prototype for this head printing PEEK: YouTube - Introducing Hyrel's MK1-450 Printing PEEK and PC

I work for Hyrel 3D. The company page is linked in my profile.

Greenonline
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Davo
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  • That's a seriously high temp for stock hotends! – Carl Witthoft Jul 27 '18 at 13:20
  • Why not add ULTEM (PEI) which is easier to print. This is not something that normal "hobby" printers can print out of the box. Also the bed temperatures associated for printing these materials are pretty high for such printers to reach. – 0scar Jul 27 '18 at 13:40
  • @0scar - we're not restricted to hobby printers here, and I think it is often useful to see the 'high end' answer to these questions - it can help to drive innovation. – Sean Houlihane Jul 27 '18 at 15:30
  • @CarlWitthoft I agree about limitations, if the OP has an plus $ 8k machine capable of +360 °C I'll take back my comment and I'll secretly be very jealous :-) – 0scar Jul 27 '18 at 19:04
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    Why $8k? I have a $2500 machine with a stock $450 head that prints PEEK at up to 450C. And I find PEEK much easier to print than PEI. – Davo Jul 27 '18 at 20:14
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    @0scar This might be of interest to you, if you haven't already stumbled upon it: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170000214.pdf – typo Jul 28 '18 at 14:16
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    @Davo Nice setup! Very interesting, please share your machine and print head in the answer! – 0scar Jul 28 '18 at 14:27
  • @typo Very interesting stuff that you can find on NASA's technical report server! Thanks for sharing, very much appreciated. Also please update your question to include the printer you have, this may limit the amount of filament options. – 0scar Jul 28 '18 at 17:25
  • @0scar Details added. And note that Hyrel equipment is mentioned in that NASA article, even though we're not open-source. – Davo Jul 29 '18 at 15:47