DESIGN TIP: Choosing Industrial 3D Printing for Production Parts

Using 3D printing for fully functional end-use metal and plastic parts is becoming increasingly common in rapid manufacturing with industrial-grade processes like direct metal laser sintering (DMLS) and selective laser sintering (SLS).

Industrial-grade 3D printing is well suited to produce organic shapes, like this nylon turbine (left) and end-use production parts such as this titanium drill component (right).

With an expanding material selection and improving material properties, designers and engineers have another good option for small quantities of production parts.

Accordingly, our monthly design tip covers this emerging trend.

This month’s tip discusses:

  • Choosing the best 3D printing process for your application
  • Selecting the right thermoplastic and metal materials
  • Designing part geometry for 3D printing
  • Using SL, SLS, and DMLS for end-use production parts

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INDUSTRY SPOTLIGHT: Commercial 3D Printing for Production Parts

Technology in the 3D printing space is advancing at the speed of light—everything from support structure software to material options and properties to ever improving processes. Some simply take these advancements as small steps in the overall progress of 3D printing, but these improvements are significant attributes that add value across industries and applications. 

Nylon handheld device 3D printed with SLS.

Medical and Health Care Development
Industries are adopting this technology for varying applications at very different paces. The health care industry has embraced nearly all forms of printing, but has particularly grasped onto direct metal laser sintering (DMLS). As we discussed last month, DMLS has a solid advantage over other 3D printing processes since it produces functional, production-quality parts from metal powder.  When plastics are concerned, selective laser sintering (SLS) is another additive manufacturing process with production in mind.

Product developers, designers and engineers in the medical and health care industries use many different types of 3D printing technologies, but why?

  • concept modeling and prototyping during early phases of product and device development
  • iterating design often to get parts in hand fast
  • reducing financial and design risks
  • building high-quality assemblies for end users to evaluate and influence human factor designs

TIPS WITH TONY: 3D Printing Living Hinges

Did you know that living hinges are possible with 3D printing? Here are a few things areas to keep in mind when designing hinge functions so your part’s functionality and integrity remain intact.

Process
We offer two processes for 3D printing thermoplastic or thermoplastic-like materials: selective laser sintering (SLS) and stereolithography (SL). But only SLS will produce parts with the functionality required for a living hinge.

An SLS part with living hinge functionality.

Material
Anytime we see the potential for a living hinge in a 3D-printed part, we will strongly guide you to SLS. SLS uses nylon thermoplastic, primarily PA 850 Black, which is a nylon 11 material. PA 850 has an increased EB of 14-51% followed by ALM PA 650 with an EB of 24%.

However, you can’t take a part that was produced in PA 850 or ALM PA 650 and expect it to function as a living hinge without a secondary process first. When you have a living hinge, we need to know what direction or the range of motion in which the hinge may function. This is critical as we anneal the part by heating it to 250-275°F and flex the hinge in the intended range of motion. This extends the life of the living hinge by stretching the material instead of fracturing the links of resin.

SL offers thermoplastic-like materials, but they are not be recommended for living hinge applications. Somos 9120 is our most flexible material of all SL resins with an elongation at break (EB) of 15-25%.

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TIPS WITH TONY: Can 3D-Printed Parts Take the Heat?

Here’s a question that’s often asked: How do materials used in 3D printing compare to injection-molded thermoplastics when the temperature rises? To answer that, I’ll briefly dissect the materials used in stereolithography (SL) and selective laser sintering (SLS) processes as these are commonly compared to injection molding.

Stereolithography
SL involves a thermoset resin that is solidified by an ultraviolet laser, followed by a UV post-curing process to completely solidify the resin. As far as material properties, the big takeaway is that SL parts are built from thermoplastic-like resins, so they do break down over time in direct UV light.

SL uses materials that mimic ABS, polypropylene and glass-filled polycarbonate, and they offer an array of material properties still exist. But today we’re concerned with the thermal properties of the materials that are best suited to handle the heat — 3D Systems Acura 5530 and DSM Somos NanoTool. Both are offered in post-cured states and there’s an additional process for thermal post-curing that increases the operating temperatures.

The chart shows optimal heat deflections for SL materials. The other materials offered in SL have a much lower heat deflection ranging from 120˚F to 177˚F.

Material

UV Post-Cure

UV Post-Cure +
Thermal Post-Cure

3D Systems
Accura 5530

85˚C (185˚F)

250˚C (482˚F)

DSM Somos NanoTool

225˚C (437˚F)

263˚C (506˚F)

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3D Printing Fully Functional Parts with Selective Laser Sintering

Selective laser sintering (SLS) is an industrial-grade 3D printing process. It builds durable nylon prototypes and functional parts using a laser that “draws” slices of a CAD model in a bed of material, fusing micron-sized particles one layer at a time. The result is fully functional plastic parts that might have been otherwise challenging to manufacture using machining or injection molding.
This month’s tip discusses:

  • Properties and applications of various nylon materials
  • Managing the SLS build process
  • Design elements to improve eventual moldability
  • Surface finishes and post-processing
  • Maximum part size, achievable tolerances and other considerations.

Read the full design tip here.