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FDM Printing

FDM (Fused Deposition Modelling) printers are probably the most widely recognised from social media posts. This specific technology is also known as FFF (Fused Filament Fabrication).

This technology uses thermoplastic materials that get melted and extruded through a small nozzle. The nozzle moves around the build volume to deposit the material in layers. 

Significant advantage of FDM process is the variety of available materials.

Parts printed using FDM have a unique look as the layer lines are usually easily visible. Material choice and colour also play a key role in how the finished part will look like. It is possible to sand and paint the parts if you require very specific look for the part.

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Yellow 3D Printed Shape_edited.jpg
Pros

  • Wide material selection

  • Cost effective

  • Suitable for production parts

  • Fast turnaround

  • Minimal post processing

  • Can print relatively large parts

Cons
  • Cannot produce small detailed features
  • Visible layer lines
Available materials:

  • PLA

  • PETG

  • ABS

  • ASA

  • PA12-CF (Nylon with carbon fibre)

  • PC

  • TPU

FDM print sizes

The maximum print volumes are dependant on material used.

  • 290X290X390mm - PLA, PETG

  • 290X240X290 - ABS, ASA, PA-CF, PC​

How to design parts for FDM printing?

Like any other manufacturing technique, 3D printing has it's own best practices and things to be aware of. 

Below we have highlighted some key design considerations for FDM printing specifically. 

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Print Orientation

Orientating the part for printing is an important consideration for design. Here are some key things to consider:

Part strength

As FDM print deposits material in layers the parts are weaker in the direction of the layer lines as the layers can separate from each other.

Print bed contact area 

During printing it is important that the print is attached to the print bed on the printer and does not move. The design should provide adequate contact area for printing. Sometimes it is not possible to optimally orient the part. In these instances printed support structures can be used. However, these also come with downsides like extra post-processing and worse surface finish.

Surface finish

Part orientation plays a big part in the final look of the finished component. Steep overhangs and supports should be avoided for best surface finish. 

Unless you provide us specific instructions on how to orientate your parts, we will orient it for best printing performance.

Overhangs

As layers get produced by the printer, the top layer has to be connected to the layer below it. It is not possible to print in the air without having support from the previous layers.

If the part has an overhang that is greater than about 50 degrees, then a support structure is needed. Ideally the the design should not have steep overhangs, but that is often not possible. If the overhang is too steep, then a support structure can be used to allow printing. This however has the downside of degraded surface finish on the part.

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Overhangs_edited.jpg

Tolerancing

Generally the tolerance for FDM printed parts is +-0.5mm at the lower end. Generally the tolerances are less than this, but this is heavily dependant on the material, geometry and specific printer used.

For connected parts/features that need to sit inside each other we recommend minimum of 0.5mm clearance.

If you are looking to produce a batch of parts with close clearances we always recommend getting a sample printed for fit trial first.

Thin walls

We recommend that your model do not include any sections thinner than 1.0mm. Even at 1.0mm the walls are generally weak with very little strength. We recommend that wherever possible you use minimum wall thickness of 2.0mm.

Please note that although we do carry out checks on all models for printability, we cannot ensure that thin walls under 1mm are printed correctly.

Holes

Our experience with various printers over the years has shown that holes tend to print slightly smaller than what is specified by the model. We have found that generally, increasing the hole diameter by 0.2-0.3mm has given us good results - this is not a guarantee for your design though. Keep in mind that if the hole ends up being a bit too small you can always drill it larger. However, it is not easy to make it smaller. (Note: given that 3D prints are not generally solid internally re-drilling a significantly larger hole in the part can result in a weaker part.)

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We also do not recommend printing holes smaller than 2.0mm in diameter. If your design includes holes smaller than this, we can print it, but we cannot guarantee the dimensional accuracy of it.

Pins

If you want to print pins as part of your design we recommend minimum diameter of 3.0mm.

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