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I've been looking into the viability of manufacturing a replacement part for a kitchen blender that has a broken part. I found this page that talks about what makes a print food safe. One of the items mentioned was:

... a brass extruder may contain lead, and lead contamination can cause some nasty health problems. ...

I own an Ender 3, and I haven't replaced the nozzle yet. How can I tell if my printer is capable of creating food safe prints in its current state?

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    $\begingroup$ Note that the concern about lead is mainly theoretical; nobody has demonstrated that you can actually detect the lead in finished prints. The nozzle has around 2% lead. How much of that makes it into the print, and then how much of that makes it from the print into your food? Probably not that much... $\endgroup$ – Tom van der Zanden Sep 18 '18 at 6:37
  • $\begingroup$ While mainly theoretical, food packaging manufacturing standards are very complex. $\endgroup$ – Trish Sep 18 '18 at 9:11
  • $\begingroup$ I'm voting to close this question as off-topic because this is a metallurgy question, not a printing question $\endgroup$ – Carl Witthoft Sep 18 '18 at 14:52
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    $\begingroup$ @CarlWitthoft Sure, but it is directly related to 3D Printing, How is that not applicable here? $\endgroup$ – ifconfig Sep 18 '18 at 15:09
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    $\begingroup$ When you say "manufacturing a replacement part", are you talking about something you would do commercially and sell the part, or just a repair for your own blender? If the former, your question is about regulations; if the latter, it's about understanding any risks well enough to make an informed decision. $\endgroup$ – Dan Hulme Dec 12 '18 at 10:46
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Food packaging needs to comply with regulations. One certification agency informing about these (and their service to certify for them) is TÜV Süd, another is SAI global. A summary of the GFSI can be found here. Inform yourself about the standards you wish to apply! The stack can not give legally binding answers.

No

The Ender 3 is not approved to produce food products (and not usable for them out of the box) for lack of certification. In the design it comes from the box, you need to replace a lot of parts for food rated ones:

  • The whole print head/bed need to be swapped out for food rated parts due to the exact composition being not known. They might contain banned materials. As a result:
    • You'll need an all-metal hot end that can be taken apart for cleaning up to the standards if needed.
    • You'll need a food rated PTFE tube.
    • You'll need a stainless steel nozzle that complies with food grade manufacturing demands.
    • The extruder gear should be stainless steel as well.
    • You'll need to add some part to prevent filament shreds/flakes from the extruder to enter the print area as they might act as contaminants or carry germs.
    • Similar measures have to be taken for the wheels on the hot end carriage, as it might shred.
    • As you include a volume of air into the print, you are likely to be demanded to print under a protective atmosphere to make sure no germs are inside the print.
    • We do not know the composition of the build platform, so you'd need to replace the back surface with something that is food rated.
  • You'll need to post-process your prints as smooth as possible, especially because of the small edges at the layer boundaries, which can and will act as spots where germs can grow.
    • This can be achieved with a material that is smoothable in some way.
    • Alternatively, a sealing lacquer/coating that is food safe might help here.

Remember, safety first:

Printed plastics that are rated for food are not necessarily food safe because of the quality or blend of the material. PLA and ABS can be made food safe, but that is usually pure material. We usually don't know what kinds of fillers or coloring is in our filament. The heating process might destroy the colors or fillers, which in turn might make it unsafe.

Indirect manufacturing

If you are stone set you want/need, you can use indirect manufacturing: you don't print the actual object, you print a mold that makes the actual object. Clay and other ceramics can be made food safe very easily and they can be shaped with plastic molds.

Boxing

There is also another way to facilitate food safety in a 3D printed container, and that is checking where the food will actually make contact. For a lunch box, that is the inside. We could line this inside with a food safe surface, for example placing a steel cup in our plastic cup-holder. Accessories like a cup holder or a decorative container for the actual food container do not need to adhere to the food packaging regulations themselves.

Exposure time

I know this is all looking at industrial food rated production. The Primer given in the question does include a point about time the product gets into contact with the food - if there is just a short exposure, you might get away with it, but it doesn't make it certified food safe. Another good read in this regard is this short discussion about the Pros and Cons.

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    $\begingroup$ they specify how a process has to be in some sort. When foaming boxes for food transport, this has to be done under protective atmosphere for a rupture of the foam would release trapped germs or contaminants. Whenever something could be brought into the product, it needs to comply, so my understanding $\endgroup$ – Trish Sep 18 '18 at 9:05
  • $\begingroup$ @TomvanderZanden Also, most of the points I mentioned are in the pimer the OP mentioned. $\endgroup$ – Trish Sep 18 '18 at 9:20
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    $\begingroup$ But there is a huge difference between "Certified food -safe" and "is actually perfectly safe for you to use at home" . $\endgroup$ – Carl Witthoft Sep 18 '18 at 14:54
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Yes you have to change brass nozzle it contains lead. If you are planning to print in PLA don't do that because PLA filament we are using in 3D printer are not food safe it contains some nasty colour dyes which are not food safe. Consider some special food safe filaments available in market. I think extruder gears are also made up of brass. Consider also changing them. Steel extuder gears are available in market like below

Exduder gear

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  • $\begingroup$ Nice note about the contributions of brass extruder gears, but the question was specific to the Creality Ender 3.and whether or not it would need new extrusion hardware. $\endgroup$ – ifconfig Sep 18 '18 at 3:46
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    $\begingroup$ Ender 3 nozzle and extuder gear are made up of brass.Before printing any food safe print you have to change nozzle and extuder gear. $\endgroup$ – Himanshu Sep 18 '18 at 4:59
  • $\begingroup$ Just not scientifically correct. $\endgroup$ – Carl Witthoft Sep 18 '18 at 14:53
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Parts printed in pla are food safe, as pla is usually made from corn starch. However, most 3d printed parts would not be food safe for they have many crevices where bacteria can grow. Also, if you printed with materials other than pla with that nozzle, traces of the material (which would make it into the print.

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    $\begingroup$ Do you know what kind of paints and colors are in PLA? Pure PLA is food grade, but you get a PLA blend as a spool. This goes for all materials btw: while ABS is generally food safe, Printing filament isn't always. $\endgroup$ – Trish Sep 18 '18 at 11:18
  • $\begingroup$ great point about sub-layer pockets, which create a hazard even if the parts and material are food-safe $\endgroup$ – dandavis Sep 18 '18 at 21:05

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