Which 3D printing technology produces the strongest functional prototypes?

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For plastic functional prototypes, SLS with Nylon 12 (PA12) produces the strongest parts with 48 MPa tensile strength, 10-20% elongation, and excellent fatigue resistance. For metal prototypes, SLM produces fully dense parts with properties matching or exceeding wrought materials (316L stainless: 530 MPa tensile, Ti64: 950 MPa). MJF (Multi Jet Fusion) nylon is comparable to SLS. FDM in PC or Nylon is also strong but anisotropic (weaker in Z-direction).

SLS Nylon - Best Plastic Strength

SLS Nylon 12 (PA12) is the material of choice for functional plastic prototypes due to its balanced mechanical properties. Tensile strength: 48 MPa. Flexural modulus: 1,700 MPa. Elongation at break: 10-20%. Impact strength (Izod): 53 J/m. Heat deflection temperature: 90°C. Parts are isotropic (equal strength in all axes), making SLS superior to FDM for load-bearing prototypes. Glass-filled Nylon (PA12-GF) increases stiffness by 50% at the cost of reduced elongation.

SLM - Metal Prototypes

Selective Laser Melting produces fully dense (99.9%+), solid metal parts. Mechanical properties match or exceed wrought/cast equivalents: 316L stainless: 530 MPa tensile, 40% elongation. AlSi10Mg aluminum: 440 MPa tensile, similar to cast A360. Ti6Al4V titanium: 950 MPa tensile, equivalent to wrought. Inconel 718: 1,050 MPa tensile. SLM parts can be heat treated, machined, and surface finished like conventional metal parts.

FDM in Engineering Materials

FDM with engineering filaments offers good strength at lower cost. PC (polycarbonate): 68 MPa tensile, 135°C HDT. Nylon 12: 38 MPa tensile, high impact resistance. ULTEM 9085: 71 MPa tensile, flame retardant, aerospace-grade. However, FDM parts are anisotropic -- Z-direction strength is only 50-70% of XY strength. For parts loaded primarily in XY plane, FDM in PC or ULTEM can match SLS strength.

Why Choose SOMI Custom Parts

At SOMI Custom Parts, we offer SLS, SLA, FDM, and metal printing services. Our engineers help you select the right technology and material for your functional testing requirements. For prototypes that will undergo physical testing, we typically recommend SLS nylon for plastic parts and SLM or CNC machining for metal parts.

Case Study

A drone manufacturer needed 50 functional prototype motor mounts for flight testing. The parts required high strength-to-weight ratio, fatigue resistance, and UV stability. SOMI recommended SLS with glass-filled Nylon 12 (PA12-GF). The mounts achieved 70 MPa tensile strength at 50% lower cost than CNC-machined aluminum, and weighed 60% less. The drones completed 200 flight hours without any mount failures.

Industry Data

SLS Nylon 12 is the most widely used material for functional 3D printing prototypes, accounting for 35% of all professional 3D printing material consumption (Wohlers Report, 2025). Metal 3D printing (SLM/DMLS) is the fastest-growing segment at 28% CAGR, driven primarily by aerospace, medical, and automotive applications.