Design for 3D Printing

May 5, 2024

Here is an article written by our engineering team that will guide you through the design requirements and guidelines of the most prominently emerging fabrication processes: 3D Printing.

From 1984 when Charles Hull created the world’s first working 3D printer, the technology has gained a tremendous amount of momentum and 3D printers have found their way into an immense number of industries. This could be attributed to the drastic decrease in additive manufacturing (AM) costs.

At Factorem, we offer a plethora of additive manufacturing technologies and materials! And this whitepaper will guide you through the general guidelines to follow when designing a part to be 3D printed.

1. Product Design with Additive Manufacturing

3D printing a part offers significant advantages over traditional fabrication processes.

  • Additive manufacturing offers decentralized manufacturing capabilities due to the portability and compactness of the 3D printers.
    • This reduces logistical expenses and helps reduce the environmental impact of the process.
  • Allows for low volume production without high start-up costs.
  • Facilitates redesigning without high lead times and cost penalties.

Beyond the production advantages, additive manufacturing is not only transforming how industries manufacture, operate and distribute goods, but also is changing the manufacturing consumer experience.

Do take some time to read our whitepaper on 3D Printing Technologies to determine what method suits your prototyping needs here: 3D Printing Technologies.

2. Design for AM — SLA

Fabrication of parts using SLA (Stereolithography) is a type of drawing on the liquid surface of the resin, therefore features that are not directly above a particular layer will require support structures. These will need to be removed during post processing.

Parts manufactured using SLA will exhibit the staircase effect especially at curved or inclined surfaces. As this affects quality, there should be some emphasis on the orientation to be faced up to minimize this effect. Other orientation dependent factors that will need to be accounted for would be anisotropic characteristics, shrinkage, build time, trapped uncured material and nesting.

SLA Printed Part
SLA Printed Part

The post processing of SLA printed parts includes draining all the excess liquid resin. Minimizing narrow passages in the design would negate the risk of liquid getting stranded in narrow passages or niches and solidifying.

Overall, when choosing to fabricate a part using SLA, the constraints that need to be considered are part size to fit in the desired machines, feature size with respect to layer size, type of resin, layer thickness, support removal and secondary processes.

3. Design for AM — SLS

SLS (Selective Laser Sintering) is one of the most straightforward types of additive manufacturing widely available in the status quo. As one of the main value propositions of SLS printing is the wide range of materials available, emphasis must be put into the choice of material during the part design. Despite the common usage of nylon materials for SLS, most available materials are offered by the equipment manufacturers. As such, the SLS machine would, to a certain extent, dictate the choices of materials that can be used.

SLS Printed Part
SLS Printed Part

SLS is best suited for parts with significant material properties. As they do not need support material, SLS is ideal to create complex geometries with inaccessible internal features.

4. Design for AM — FDM

FDM (Fused Deposition Modelling) prints by molten plastic extrusion that hardens layer by layer forming a solid part. The resolution at which the part is printed must be chosen well in advance as the nozzle cannot be changed during the print. Overhanging and isolated features required support material when printed through FDM as well. However, the higher end FDM machines offer a water-soluble material that can be easily removed using an agitated bath.

FDM Printed Part
FDM Printed Part

Overall, FDM is suitable for parts that need to be stronger compared to SLA at the expense of sharpness and surface finish. Over the years of development, the print speed of FDM machines have improved over 500%. New developments have focused on including metals, ceramics and other useful materials into FDM printing.

5. Conclusion

When designing a component, the design goals and features would be critical in identifying the additive manufacturing technology to utilize and the materials to choose from. The desired surface finishing also plays a role in this decision making. While sintered parts would have a grainy texture, FDM fabricated parts would have a ribbed appearance.

The commonly chosen technologies were discussed in this whitepaper, however additive manufacturing encompasses a wider range of methods. While the general guidelines for a 3D printed part design was discussed, each method has its own strengths in different print materials, speeds and finishes. Do keep a lookout for future articles by Factorem and follow us on our journey to #HelpMakersMake.

If you’d like to know more about the manufacturing methods and materials discussed in this paper, do take some time to read our whitepapers published on the following topics available here:

Prototyping Materials

Surface Finishing for Metal and 3D Printed Parts

Tolerance Guidelines for Sheet Metal Design

3D Printing Technologies

Drafting technical drawings for CNC Fabrication

Factorem’s ISO 2768 Machining Guidelines

Factorem’s Welding Whitepaper

Carbon Fibre Design Guidelines

Dowel Pin Tolerance and Fit Standards