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3D Printing Tolerances: What Do You Need To Know?

3D Printing - 5 July, 2024
3D Printing Tolerances: What Do You Need To Know?
Author
Vicki May
Date
5 July 2024
Category
3D Printing
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Tolerances are key in any manufacturing process, and additive manufacturing is no exception to this rule.

Whether you’re looking to connect multiple components together or provide enough of a clearance gap for another component, tolerances are crucial.

While you’re probably very familiar with including tolerances in your designs, there are some more factors to consider during the additive manufacturing process to ensure your design tolerances are just right. This guide delves into the intricacies of 3D printing tolerances, providing you with the knowledge necessary to achieve optimal accuracy and functionality in your printed components.

What Are 3D Printing Tolerances?

3D printing tolerances refer to the acceptable deviation from the specified dimensions of a part. These deviations can result from various factors, including material properties, wall thickness, uneven shrinkage of materials and layer thickness, for example.

Understanding and managing how the material responds to being printed and how this might affect your part geometry ensures that parts fit together correctly, function as intended, meet industry standards and that the production process goes as smoothly as possible.

Key Factors Influencing 3D Printing Tolerances

Printer Technology

Different 3D printing technologies offer varying levels of precision:

Fused Deposition Modeling (FDM) – Generally provides tolerances around ±0.5 mm. It is less precise compared to other methods but suitable for prototypes and less intricate parts.

Selective Laser Sintering (SLS) – SLS provides tolerances of ± 0.3mm for parts under 100mm and ± 0.3% for parts over 100mm making this type of printing ideal for complex geometries and functional parts.

Multi Jet Fusion (MJF) – Achieves tolerances of ±0.2 mm, making it suitable for parts needing a high level of dimensional accuracy and a fine surface finish.

Material Properties

The choice of material significantly impacts tolerances:

Thermoplastics – Commonly used in FDM, these materials can shrink or warp, affecting dimensional accuracy.

Resins – Used in SLA, resins generally offer better dimensional stability but can be brittle depending on the resin used.

Powdered Materials – In SLS and MJF, powdered polymers provide excellent accuracy but require careful post-processing to achieve tight tolerances.

Design Considerations

Design features play a crucial role in managing tolerances:

Wall Thickness – Thin walls can warp or break, while thick walls may not print accurately. Optimal wall thicknesses vary with the technology used and part requirements.

Overhangs and Bridges – Unsupported structures can sag, requiring support material or design modifications. 

Holes and Slots – These features often print smaller than designed due to the material’s behaviour during cooling and solidification – requiring additional steps in the manufacturing process to ensure accuracy. 

Best Practices for Managing 3D Printing Tolerances

Design for Manufacturability (DFM)

Incorporate DFM principles to optimise your designs for the specific 3D printing technology and materials. If you aren’t too sure what material your printed part should be printed with, speak with one of our engineers. They can recommend the best material and printing process for your part depending on variations permitted, usage etc.

Changes to your model can include:

  • Build orientation
  • Wall thickness 
  • Feature size 
  • Need for support structures 

Use Tolerance Analysis Tools

Employ CAD software tools that simulate 3D printing processes and predict deviations. These tools help in adjusting designs proactively to meet tolerance requirements. Our engineers use this type of software to ensure that all parts are printed as accurately as possible, and can recommend changes to your parts to ensure they are printed within specified tolerances.

Material and Process Selection

Choose the appropriate material and printing technology based on the required tolerances and the part’s functional requirements. For example, use SLA for high-detail components or SLS for larger parts.

Iterative Testing

Create prototypes and conduct iterative testing to refine designs and processes. This is a great opportunity to test different materials and processes too. This approach helps in identifying and mitigating tolerance-related issues early in the development cycle.

Once you find the design you’re happy with, the build set up can be documented and then referenced during the manufacturing of parts in the future.

Final Thoughts

Understanding and managing 3D printing tolerances is vital for producing high-quality assemblies and components, especially in demanding industries like motorsport, medicine, and energy.

From nozzle diameter to printer settings, there are a lot of different things that need to be factor into a successful print! Thankfully we have additive manufacturing engineers and experts ready to help you!

Need some help? Prototal are here from you! We have a state-of-the-art additive manufacturing facility here in the UK, and can help you produce parts to the highest quality standards!

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