Taking the time to understand material and printer capabilities and limitations will allow you to design for manufacturability and set realistic expectations when ordering 3D prints. In this article, we will go over common types of 3D printing and what to expect with each.

Acceptable File Types

You may place a 3D printing order using any of the file types listed under the 3D Printing header in this article. Please note we will not print files that contain multiple bodies. These orders will be rejected and canceled after submittal. 

FDM Process and Materials

FDM: FDM stands for Fused Deposition Modeling. FDM printers create layers by extruding molten thermoplastic material through a nozzle. Because of the nature of FDM printers, certain features may have a very thin string of material that will need to be removed by hand. (Imagine a taking hot slice of cheese pizza from the pie and the tendency of the cheese to stretch.) Parts that feature overhangs or other tricky features will require support material, which may affect the final finish of the part. At Fictiv, we use hobby-grade machines for parts printed in PLA to keep costs low, and professional-grade machines for parts printed in ABS to preserve accuracy and strength. Parts with internal cavities will be printed with a 20% infill density. Due to the low resolution of many part files exported in STL or OBJ format, some curved surfaces will have visible steps and will not appear as a smooth transition. Resolution refers to the layer height, not the dimensional accuracy and ability to hold tolerances.

PLA: PLA is great for early-stage, low-detail prototyping. It is inexpensive and recommended for parts where dimensional accuracy and aesthetic appeal are not as critical as proof-of-concept or basic form/fit. This is a low-resolution material (.2mm) with visible layer lines. Some features may require support material which is manually broken off after printing, potentially leaving noticeable residue. All internal cavities may have support material inside. The minimum wall thickness we can accept is 1mm, however, the minimum wall thickness for guaranteed prints is 1.5mm. We cannot guarantee a successful print of any parts with thinner walls. PLA is used in FDM printers.

ABS: ABS is also a relatively cost-effective material known for its strength. Because of the professional grade printers used for ABS on our network, this material can handle complex geometries, though tolerances cannot be guaranteed. Unfinished ABS prints will have visible layer lines due to the low resolution (.25mm). The minimum wall thickness we can accept is 1mm, however, the minimum wall thickness for guaranteed prints is 1.5mm. We cannot guarantee a successful print of any parts with thinner walls. All internal cavities may have support material inside. ABS is used in FDM printers. 

PolyJet Process and Materials

PolyJet: PolyJet printers work by jetting layers of liquid photopolymer and instantly curing them with a UV light. These machines are capable of creating hi-res prints and can handle complicated geometries with ease. PolyJet printers use a water-soluble, gel-like material to support overhangs and complex geometries. The support material is easily washed away by hand, assuming it is accessible (e.g., not enclosed in an internal cavity--this is strongly discouraged as the material will be trapped). To prevent warping on parts with long, flat features, consider adding ribs to increase support and structural integrity. The materials used in PolyJet printers are VeroBlack/White/Clear, ABS-Like, and Rubber-Like.

VeroBlack/VeroWhite: Vero is great for fit testing late-stage prototypes and creating visual models where aesthetic appeal must be considered. It is a high-resolution material with minimally visible layer lines. The minimum wall thickness for guaranteed prints is 1.0mm; anything below cannot be guaranteed to print successfully. We do not recommend internal cavities when printing with Vero as the water-based support material may be impossible to remove and will expand over time, changing the geometry. Support material that is visible and easily reachable will be cleaned off by our manufacturing partner. Vero is used in PolyJet printers.

VeroClear: VeroClear is a translucent material that can be sanded and painted for increased transparency. It is a high-resolution material with minimally visible layer lines, assuming the print is optimally oriented on the print bed. The minimum wall thickness for guaranteed prints is 1.0mm; anything below cannot be guaranteed to print successfully. As with Vero, we do not recommend internal cavities when printing with VeroClear as the water-based support material will be impossible to remove and it will expand over time, changing the geometry. Support material that is visible and easily reachable will be cleaned off by the manufacturing partner. VeroClear is also used in PolyJet printers.

SameDay Vero: While "SameDay Vero" isn't a specific material other than Vero, it is an option that you will see on eligible parts. Parts printed with the SameDay Vero option will print in either black, white, amber, or clear--this all depends on what color is pre-loaded on our manufacturing partner's printer. To be eligible for SameDay Vero, parts must not exceed a certain size, and orders must be placed by 10am for same-day turnaround. The rules that apply to Vero apply here as well.

ABS-Like: ABS-Like has the same hi-res look as Vero, but is much stronger and more durable. It is great for high accuracy parts. As with most 3D printing materials, a minimum wall thickness of 1.0mm is needed to reduce the risk of breakage during printing and cleaning. Any walls under 1.0mm in thickness are not guaranteed to print successfully. Internal cavities are strongly discouraged as the water-based support material will expand over time, affecting the geometry. Support material that is visible and easy to reach will be cleaned off. ABS-Like is used in PolyJet printers.

Rubber-Like: Rubber-Like is a black elastomer that mimics the flexibility of rubber parts, although it is not as elastic. It’s great for printing overmolds, soft-touch finishes, non-slip surfaces, and water-tight seals. It’s available in shore values ranging from 27A to 90A. Though it is high-resolution, build lines may be more visible due to the nature of the material. Due to the nature of Rubber-Like material, the minimum wall thickness is 2.0mm; anything below cannot be guaranteed to print successfully. As with all other PolyJet materials, we do not recommend internal cavities when printing with Rubber-Like as the water-based support material will be impossible to remove and will expand over time, changing the geometry. Support material that is visible and easily reachable can be cleaned off. 

SLS Process and Material

SLS: SLS stands for Selective Laser Sintering. SLS printers create layers by sintering Nylon powder that is spread evenly on on the print bed. SLS printers do not use a different support material; rather, the Nylon powder acts as the support material during the build. For this reason, we strongly discourage internal cavities and other tight features which may trap the Nylon powder. Unlike our FDM printing standards, SLS printers will produce solid infill.

Depending on the size of the part, the process of cooling the finished parts may take just as long as the print time, which contributes to the reason why SLS Nylon carries a longer lead time than our other offerings. Cooling layers too quickly can result in warpage of large parts. Large, flat parts are especially susceptible to cooling unevenly and warping. To combat this, consider adding ribs to flat parts if possible, and avoiding printing large flat parts with SLS.

Nylon: Nylon is not as hi-res as our PolyJet offerings, but it is still superior to the FDM resolution. Nylon parts are printed on SLS machines, so keep in mind your part should not feature any internal cavities as the unsintered nylon powder will be permanently trapped within your part. The heat emitted by the lasers and subsequent cooling process may cause shrinkage on large parts and warpage on areas that are below 1.5mm in thickness. Nylon is strong, durable, and has some flex, making it great for snap-fit components, brackets, and clips. Nylon is also great for thermal applications, as it can withstand temperatures of up to 177-degrees Celsius (350-degrees Fahrenheit). The texture of Nylon parts is similar to that of fine grit sandpaper with a matte finish. 

Designing for Manufacturability

Please keep in mind we do not offer DFM review for 3D printed parts other than monitoring for walls that are too thin to print reliably, and we cannot control printing orientation. However, with the above capabilities and expectations in mind, you should be able to design for manufacturability and set realistic expectations.

For a more in-depth look at our processes, materials, and finishes, please check out our Capabilities Guide.

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