TIPS WITH TONY: Shedding Light on Clear Materials

Designing luminaires or lenses with clear materials? Our tip this week looks at the material selection and surface finishes available for prototyping and low-volume production of lighting applications.

Prototype built in clear WaterShed XC 11122 material with stereolithography.

Additive Manufacturing
If you haven’t considered using additive manufacturing (3D printing) for your lens design, you may want to check it out. Proto Labs offers stereolithography (SL) with three options for clear parts.

  • Somos WaterShed XC 11122 — ideal for lens and high-humidity applications
  • 3D Systems Accura 60 (10 percent glass-filled) — creates a clear part with slight blue tint and high stiffness
  • 3D Systems Accura 5530 — high temperature resistance, suitable for under-the-hood applications

TIPS WITH TONY: Additive Manufacturing for Microfluidics

Prototyping small volumes of microfluidic parts has traditionally been difficult using CNC machining or injection molding, but Proto Labs offers microfluidic fabrication through additive manufacturing (3D printing) for just this purpose.

Microfluidics typically requires very flat surfaces, and clear and thin/shallow features that are difficult to produce in a mold that is milled and hand polished. These tiny features are not easily distinguishable, requiring careful polishing and injection molding pressures can sometimes role the edges even further, not to mention the effect that the ejector pins have on the part surface. Ejector pins play a huge factor in removing the part from the mold and can cosmetically impact microfluidic parts that are molded. We will continue to injection mold microfluidics, but please first discuss these projects with a customer service engineer at Proto Labs.

Additive Approach
Additive microfluidics changes all of this as ejector pins are a non-factor. We use stereolithography (SL) to produce parts using an ultraviolet laser drawing on the surface of a thermoset resin, primarily our Somos WaterShed XC 11122 material. High-resolution SL is able to produce features as thin as 0.002 in. layers to provide the fine detail that microfluidics require. We recommend channel sizes of 0.025 in. square cross sections with a minimum wall thickness of 0.004 in. for X and Y dimensions and 0.016 in. for the Z dimension. Of course, we can produce features smaller than this, but it would need to be carefully reviewed by our engineers before the build begins.

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TIPS WITH TONY: Fine-Tuning Your Additive Resolution

When you’re watching an epic movie filled with sweeping cinematography, you probably want the highest on-screen resolution possible with, say, a Blu-ray disc or high-definition stream. But if your children are watching old Disney movies in the playroom while arguing with each other over Legos, a standard picture from a classic DVD will probably suffice. The point: Don’t overpay for something that isn’t really necessary.

Normal resolution.

Normal Res
The same thought can be applied during 3D printing when you’re prototyping with stereolithography (SL). Proto Labs uses three resolutions that range in cosmetics and functionality. Normal resolution (NR) provides the lowest cost, but lacks fine detail. With NR you get a layer thickness of 0.004 in. with a minimum feature size of 0.010 in. — but that might be all you need in early prototyping.

High resolution.

High Res
If your part requires an elevated level of precision, there’s high resolution (HR). Here, you get a layer thickness (0.002 in.) and minimum feature size (0.004 in.) half of NR. It costs more, but the boosting the part quality may be well worth it depending on your intended application.

Micro resolution.


Micro Res
You can even step up to a higher level of precision, which most manufacturers are unable to provide. Micro resolution (MR) — the Blu-ray of additive resolutions, if you will — can provide optimal part detail on the smallest of part features. With MR, you get a layer thickness of 0.001 in. and minimum feature size of 0.002 in. Yes, that is an actual life-sized ant (not an evil oversized ant) atop a microscopic chess board. You can even see the staircase inside the rook!

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Why Stereolithography is Built for Prototyping

Stereolithography (SL) is an established additive manufacturing process that can quickly and accurately create complex prototypes. Parts are built by curing paper-thin layers of liquid thermoset resin with an ultraviolet (UV) laser that draws on the surface of a resin to turn it from a liquid to solid layer. As each layer is completed, fresh, uncured resin is swept over the preceding layer and the process repeated until the part is finished.

SL offers a range of plastic-like materials to choose from with several types of polypropylene, ABS and glass-filled polycarbonate available. Normal, high and micro resolutions are achievable at Proto Labs, meaning very fine details and cosmetic surfaces are possible. As a result, minimal “stair stepping” is seen compared to printed parts such as fused deposition modeling (FDM).

SL parts can also be built to a max size of 29 in. by 25 in. by 21 in., giving it the edge over other additive processes like selective laser sintering (SLS).

Our latest design tip looks at these and other manufacturing considerations for the stereolithography process.

An Inside Look at Advanced 3D Printing

We’ve watched a design move from 3D CAD model to final part. We’ve stepped inside high-speed CNC machine. And we’ve looked at how injection molding can produce quick-turn plastic, metal and liquid silicone rubber parts. We’re closing our video series with topic of many manufacturing conversations as of late: 3D printing.

Additive manufacturing (aka 3D printing) is increasingly being used to rapidly build prototypes and even functional, end-use parts. Proto Labs employs three advanced additive processes: stereolithography (SL), selective laser sintering (SLS) and direct metal laser sintering (DMLS). Check out our short video to see how additive manufacturing at Proto Labs can help on your next project.