3D Printing

3D Printing is an additive manufacturing method that involves laying down thin layers of materials (mostly plastic) in order to create products with minimal preparation needed. Albeit time-consuming, 3D printed parts revolutionized prototyping and they are also used in scenarios where conventional molding and tooling aren’t able to deliver desired outcomes (i.e: in generative design). We can provide most 3D printing jobs in 5 days. You need to provide STP/STEP files or an equivalent for us to print from. Sometimes we print one-off designs as proof of concept. It’s also possible to see parts of 20-30 coming from our industrial 3D Printing vendors for larger-scale design confirmation.

Supported 3D Printing Methods

While there are new 3D printing technologies coming out regularly, we use a number of tried and tested technologies in or manufacturing:

1. Fused Deposition Modeling (FDM),
2. Stereolithography (SLA), and
3. Selective Laser Sintering (SLS).

Fused Deposition Modeling (FDM)

FDM is especially popular due to how cheap and easy it is to use. It’s also open-source and has large communities on the internet such as Thingiverse where you can download a large number of community-maintained designs. FDM works like this:

1. The machine’s nozzle heats up and melts the thermoplastic (commonly FDA and ABS) filament inserted during the setup.
2. The melted filament drips and deposits on the base.
3. The nozzle is then moved by the motor controller following a predetermined track.
4. The process is then repeated for the next layers until the 3D model is done.

Since 3D printing is done by depositing layer over layers of resin, any part created on top of the structure must be well supported by the structure underneath. Hence, while creating overhanging parts or bridges, temporary supporting structures are needed to prevent the part from dropping.

Once finished, the support will be removed from the part, and the part will be polished. To remove the roughness of the printed object, sandpaper with the help of water is rubbed onto the product. The choice of sandpaper could be 180 for rough polish, 240 for standard polish, and 320 for finishing.

You shouldn’t expect superb visual quality from FDM parts. Your primary goal for using FDM parts should remain testing product functionality, not aesthetics.

Stereolithography (SLA)

Stereolithography or SLA printing involves the selective exposure of liquid resins to light in order to form very thin solid layers that stack up to create one solid object. The resins used in the SLA process are light-reactive thermoset liquids, not thermoplastic. The liquids are initially monomers and/or oligomers which are then exposed to UV to form polymer bonds. Since the starting resin is liquid, parts that come out have superb smoothness. It’s highly recommended for manufacturing pieces with tight tolerances and smooth surface requirements. Although usually more brittle than FDM parts, SLA is great for demonstrating the visual aspects of your final product.

Once printed, you should remove excess uncured resin from the printed model surface. This could be done directly by hand or by using an additional tool such as tweezers and pliers.

Using an isopropyl alcohol bath or equivalent can also clean the uncured resin. We can also offer post-curing to add more tensile strength to the SLA products.

Selective Laser Sintering (SLS)

source: H. Petterson and G. Flodberg, "Mechanical performance of polymer powder bed fused objects", DOI:10.1016/j.addma.2018.10.009

SLS uses a high-power laser to sinter polymer powder particles together to form a solid structure. The process uses granular resin or thermoplastic polymers such as Nylon 12 which are initially heated below their melting points.

1. A feeder places a thin layer of polymer powder on the printing platform.
2. A laser scans the area, checks the contour, and shoots the heated beam on the printing locations to allow the powder particles to sinter (bind together).
3. Once the layer is done, the feeder reapplies another layer of powder, and the procedure continues until the solid structure is finished.
4. Cool down the structure for around 12 hours.
5. Clean the structure using media blasting.

SLS products have better and more consistent mechanical properties, than when done by FDM or SLA printings. SLS is also a more environmentally friendly process since all of the unsintered grains of polymers can be reused (SLA can only recycle 50%).

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