How strong is an SLS-printed part?

Three factors determine final strength: material choice, print parameters and build orientation. Material has the biggest effect — PA12 hits 45 MPa, PA11 hits 54 MPa, fibre-reinforced variants exceed 56 MPa. Build orientation matters less for SLS than for FDM, but for fibre-reinforced materials it still counts.

Our print parameters (laser power, scan speed, bed temperature, lay-down density) are calibrated to maximise density — typically 98-100% of theoretical solid material. Higher density means higher strength and better sealing properties. Our EOS P500 dual-laser machines deliver a consistent thermal environment across the entire build.

For PA12, SLS tensile strength (45 MPa) is in the same range as injection-molded PA12 (~50 MPa) — within ~10%. For most functional applications that difference is not decisive. FDM-PA12 sits at around 35 MPa and is anisotropic (weaker in the Z direction), making it mechanically less predictable.

In practice: SLS PA12 parts are used in industrial end-products — automotive aftermarket, medical devices, agricultural machines, ATEX installations. The materials are certified and the process is repeatable. For regulated applications (medical, food contact) we offer PA12 Blue MD with FDA + EC1935/2004 documentation.

A few design choices improve the mechanical performance of your part:

• Minimum wall thickness 1.5-2 mm for load-bearing parts (1.2 mm is enough for supporting structures)
• Reduce stress concentrations: rounded transitions (R ≥ 0.5 mm) at internal corners
• Avoid large solid volumes: shell with 2 mm walls and internal ribs for better cooling and lower thermal stress
• Choose a fibre-reinforced material for structurally loaded parts — Carbon LW or PA802CF
• For sealing against liquids: post-process with cyanoacrylate infiltration

Our engineers review the design free of charge if you upload it — ask specifically for a DfAM check.