Achieving transparent 3D prints can be tricky, and much care must be taken to get the best results. In this article, we’ll discuss whether full transparency can be reached, transparent FDM filament options, and transparent alternatives to FDM. For clarity, this article will only discuss filament for industrial FDM 3D printing.
Is Full Transparency Possible?
Full transparency requires that light is not refracted, or distorted, as it passes through an object. Unfortunately, FDM 3D printing uses print head nozzles that create parts with rounded layer boundaries as the material is extruded. Given the curved shape, light is easily refracted as it passes through the layers and makes 100% transparency impossible regardless of material, printer settings, or post-processing practices. This means that a part produced with clear material via FDM 3D printing will turn out to be translucent, or blurry, when looked through.
However, by altering printer settings and design specifications, it is possible to control this translucency so near perfect transparency may be achieved. For printer settings, layer height may be adjusted to be larger so that it takes fewer layers to construct the part. With fewer layers, there are fewer boundaries against which light may refract, though using larger layers may mean that smaller features of your part are less defined. These larger layers will also require that the printing speed be reduced to avoid excess oozing or similar errors in accuracy. As for design specifications, reducing wall thickness and the amount of infill can help with transparency as well. This is because when light tries to pass through multiple layers, it only becomes further refracted. Ideally, your walls would be only one layer thick to allow for best transparency. However, this and less infill can both degrade the strength of your finished part.
In post-processing, a part may be sanded, chemically smoothed, or spray or epoxy coated to help increase transparency. The smoother a surface is, the higher transparency it will have.
Clear Filament Options
There are several FDM filament options that will give you satisfactory transparency. We’ve provided a brief description of each below:
ABS is the most common FDM material as it is the simplest material to print industrially and it exhibits excellent strength and impact resistance for moderate stress environments. When printing with transparency in mind, it is important to note that an additive is used in the filament to make it clearer. This material is able to be smoothed with acetone vapor in post-processing for increased transparency.
PET & PETG
PET and PETG are both clear materials. PETG is the combination of PET and glycol, which makes PETG stronger and less brittle than PET. Particularly, PETG is better if you are aiming to make bigger parts that will be under strain.
PLA is made from corn starch and sugar cane, which gives it a natural transparent appearance. However, all PLA filaments have a yellow tinge that may be more pronounced depending on how each company processes the material. For best results, PLA parts are sanded and polished in post-processing. While not likely to warp or shrink during printing, it is often very brittle and is, therefore, best used for cosmetic pieces. This is the only material on this list that may be reliably produced on a desktop 3D printer.
PMMA is better known as acrylic, which, in sheet form, is often used in place of glass like you might find in windows or aquariums. It is strong, impact resistant, and lightweight. While comparable to polycarbonate, it is often preferred because it is cheaper. It may be made smooth with acetone in post-processing.
Polycarbonate is a strong material capable of handling loads where flex is required. For example, when thermoformed in sheets, it is often used to make bulletproof glass. As for 3D printing, to get better optical clarity, it must be printed at extreme temperatures, optimally around 500°F. It can be smoothed with acetone in post-processing for a smooth, glossy finish.
Polypropylene is durable, fatigue resistant, and lightweight. It is naturally a light shade of translucent beige, but it can be made optically clear. However, this material has low transmissivity, and it is suggested that for better transmissivity, PMMA or polycarbonate be used.
TPU is a flexible and elastic material that can be made in varying shore values so as to mimic the qualities of soft rubber, hard plastic, and anywhere in between. While flexible filament is more difficult to print, this material can produce excellent clear parts for many applications that require stretching or compression.
Alternatives to Transparent Filament
If transparent filament doesn’t seem like the right fit, there are a few other options to explore. SLA, PolyJet, and MultiJet 3D printing all use resins to construct parts. With these technologies, layer lines are less visible, so transparency may be more easily achieved. However, these technologies are best used for cosmetic pieces only, not functional parts.
Thermoforming may offer another solution. To produce parts, it heats full sheets of plastic and draws them over a mold. It is commonly used to form parts, particularly containers and glass inserts, from acrylic, polycarbonate, and more.
3D Printing at 3 Space
Here at 3 Space, we offer multiple 3D printing services, including FDM, PolyJet, and MultiJet. We also offer thermoforming and other traditional manufacturing methods. If you have questions or concerns about the transparent materials we carry or need help deciding which technology or material will best suit your needs, our engineers are happy to assist you. For more information, contact us today.