Food-Safe 3D Printing Guide 2022
FDM, SLS and SLA
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3D printing is a manufacturing process that allows designers to develop creative and unique designs for plastic products.
Creative designers understand the potential 3D printing could have for food-related applications. However, there are various health barriers that they have to overcome to be successful in this space.
Food safe 3d printing is possible, and more and more materials are becoming available every day. However, there is a lot of confusion on what is considered “food safe.”
This guide aims to address 3d printing food safe best practices, what materials can be used, and considerations that must be made to meet food safety requirements in Australia.
Food Safety Requirements
Food safe is a term used to describe equipment that does not impose a safety hazard when in contact with food. According to Australian government food standards, for food equipment to be food-safe, equipment must:
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Not cause food contamination
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Be easily cleaned and free of cracks, chips, ridges and grooves
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Be made out of material that will not contaminate food
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Be unable to absorb grease, food particles and water to cause contamination.
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Be well maintained
3D Printing Food Safety Considerations
Bacteria Build-up:
Bacteria build-up is an important consideration to make for 3D printing food equipment. Harmful bacteria such as E.coli and salmonella can hide within layers and cause potential harm.
This is not an issue for disposable items, but if you intend to keep the 3d printed part for an extended period, using a food-safe coating is highly recommended.
Food Safe Equipment:
Equipment used during the 3D printing process should be food-safe and not cause contamination
Design:
Correct design can assist in minimising bacteria build-up. The primary design considerations include:
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Avoiding sharp corners.
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Using smooth edges.
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Printing without support if possible (FMD)
Heat:
Depending on your method of 3D printing, heat could potentially become a problem. Due to having a low deflection temperature when exposed to high temperatures, 3D printed parts are at risk of softening, distortion or potentially breaking.
If you intend to use a dishwasher or hold hot liquids with your design, make sure to double-check the chosen materials properties.
Material Contamination:
Not all 3d printing materials are food safe. Many contain chemicals that could be potentially harmful.
Food-Safe Stereolithography (SLA)
Is SLA resin food safe? Unfortunately, no.
SLA printing can potentially leach chemicals, even when cleaned and cured. Although the chance is slight, we would never recommend using SLA prints for food products.
However, there are alternative ways to use SLA to still get that unique, custom design that you would like.
Using SLA Printed Parts as Molds:
One way to leverage the benefits of 3D SLA printing is to 3D print vacuum moulds. While SLA prints themselves are unsuitable, these moulds can be vacuum formed using a safe plastic alternative to create stunning designs without coming into contact with toxic materials.
Ceramics:
Ceramic SLA painting materials can be used to create unique ceramic 3D printed parts. Once fired in a kiln, the SLA printed model can burn out the resin, leaving a smooth, heat-resistant, strong part. However, to use these parts long term, food-safe glazing should be applied to decrease the likelihood of bacteria collection and make the part chemical resistant.
Food-Safe Fused Deposition Molding (FDM)
Is 3D FDM printing food safe? Sometimes.
As FDM parts have tiny ridges and voids, they can sometimes become a breeding ground for harmful bacteria. For disposable or short-term use, these parts (if created using correct practices) can be used as food-safe products. However, these parts become unhygienic in the long term.
Food safe epoxy or polyurethane resin can be used to stop potential bacterial buildup. However, not all coatings are dishwasher safe or safe for prolonged use.
Another consideration when using FDM printing to create food-safe products is heat. Many plastics used in an FDM printer will soften and distort at around 60-70 degrees celsius. So if you are making an FDM printed teacup, you are going to have a bad time.
FDM Food safe 3D printing materials:
Many 3d printing materials could potentially contain toxic chemicals and are therefore not food safe. When designing 3d parts that will come in contact with food, ensure that they are certified for food safety. Some food-safe materials include:
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ABS
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PLA (without additives)
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PETG
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Natural Grade Nylon
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Polypropylene
NOTE: If you intend to print for long term use, it is highly recommended to use food-safe coatings/sealants.
For more information about food-safe 3d printing materials, refer to formlabs guide to food-safe 3d printing.
How to ensure your FDM 3d printer is food safe:
As particles from the 3d printer may become fused into 3d parts created, the printer must be food-safe before printing. Some considerations to make include:
The material of the nozzle:
Generally, many FDM printers will be fitted with a brass nozzle as it offers excellent heat transfer at a low cost. Unfortunately, these brass nozzles are made up of 2% lead, which could contaminate your design. Although unlikely, there is still a chance, so it is always better to take precautions. Stainless steel nozzles are a safer alternative and have been accepted by organisations such as the FDA as food-safe.
Cleaning the drive gears:
Before a filament change, it is always good practice to clean your FDM printer’s drive gears/rollers. This is because it could potentially contain powder from previous filaments that could contaminate your print.
NOTE: lubricant used should also be food-safe, even if it does not directly contact the filament.
Cleaning of the PTFE tube:
When changing filaments, be sure to remove the string and push out any leftovers using the new filament.
Food safe 3D Printing with Selective Laser Sintering (SLS)
Are SLS printed parts food safe? Mostly.
SLS printed parts are graded as food-safe but do not deal well with moisture very well. Parts printed using this method are typically made of nylon or similar material, which do not deal well with mould. To combat this, food-safe coatings are suggested to increase the prints water resistance.