Accuracy for 3D Printed Plastics

Please use the following guidelines for tolerances and accuracy of 3D printed (additive manufactured) components. Note that this is based on typical results.

  • SLS: +/- 0.005" or +/- 0.002" per inch, whichever is greater, is typical. Build area up to 13 x 13 x 20" (13" max dimension preferred)
  • HP MJF: +/- 0.012" or +/0.003" per inch, whichever is greater, is typical. Build area up to 15 x 11 x 15" (14 x 11 x 13" is the recommended usable area)
  • FDM: +/- 0.004" or +/- 0.002" per inch, whichever is greater, is typical. Build area up to 24 x 36 x 36"
  • SLA: +/- 0.004" or +/- 0.001" per inch, whichever is greater, is typical. Build area up to 29 x 25 x 21" (up to 58" is available through custom requests)
  • Carbon DLS: +/- 0.005” for the first inch is typical, plus +/- 0.002” for every inch thereafter. However, Xometry does not guarantee tolerances on the first attempt of a new design. Tolerance expectations can vary across different materials (e.g. elastomeric versus rigid materials).
  • PolyJet: +/- 0.004", or +/- 0.001" per inch, whichever is greater, is typical. Build area up to 19 x 15 x 7"

Additional notes:

  • All processes: Stresses during build, support strategy, and other geometry considerations may cause deviation in tolerances and flatness. Parts with thicker geometries, flat or broad parts, and parts with uneven wall thicknesses may be prone to significant deviations or warp. Improved tolerances may be possible with a manual quote review, after successful completion of a prototype build, and must be approved on a case-by-case basis.
  • SLS (Selective Laser Sintering): Note that thicker geometries, large broad parts, and parts with uneven wall thicknesses may deviate due to thermal shrinkage and stress. This can look like warping or twisting. Even wall thicknesses and similar design guidelines as injection molded parts are encouraged. Very small gaps and holes may be tighter than designed, a 0.006" offset of small gaps and holes will help these features achieve closer to CAD results. SLS prints in 0.0047" (120 um) layers.
  • HP MJF (HP Multi Jet Fusion): Note that thicker geometries, large broad parts, and parts with uneven wall thicknesses may deviate due to thermal shrinkage and stress. This can look like warping or twisting. Even wall thicknesses and similar design guidelines as injection molded parts are encouraged. Very small gaps and holes may be tighter than designed, a 0.006" offset of small gaps and holes will help these features achieve closer to CAD results. HP MJF prints in 0.0031" (80 um) layers.
  • FDM (Fused Deposition Modeling): FDM works well for mechanical geometries, larger parts, and parts which may not require ultra-fine features. Very narrow pegs and lips may not resolve due to the bead thickness deposited. We recommend minimum feature size, including text features, to be at least 0.035" (0.045" is safest). FDM prints in 0.010" layers (254 um), 0.013" layers (330 um) on parts over 16" max dimension.
  • SLA (Stereolithography): SLA is a very fine detail and accurate process with a high variety of photopolymers that can mimic different properties. SLA materials can range from flexible (polypropylene-like), general purpose (ABS like), rigid (polycarbonate-like), and even highly stiff composite depending on the chosen material. SLA is a reliable option for testing fit prior to injection molding, getting a part with a smooth surface finish, or highly detailed features. SLA prints in 0.004" layers (100 um) with standard resolution and many materials have a high-resolution option at 0.002" (50 um) layers. 
  • Carbon DLS (Digital Light Synthesis): Carbon DLS is a very fine detail and accurate process with thermally cured engineering materials. The cured materials are often urethane-based, such as flexible, rigid, and elastomer materials (FPU, RPU, EPU). There are also materials that behave like silicone, such as the urethane-based SIL material. Cyanate ester (CE) is a stiff and highly thermal resistant material. Urethane Methacrylate (UMA) is a general-purpose single-stage resin. Although curing is continuous, expect 0.004" layers (100 um). This process works best for end-use applications that require a good blend of mechanical use and surface quality.
  • PolyJet (Polymer Jetting): PolyJet is a very fine detailed and accurate process. Although the material is not as robust as the FDM or SLS thermoplastics, the rigid and rubber-like photopolymers have the highest detail resolution for features like text, surface, and lip seals. PolyJet prints in 0.0012" layers (30 um). This process works best for final fit-checks before molding, over-mold prototypes, and parts that are used as sales models.

Click here for Xometry's Manufacturing Standards.

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