Multi Jet Fusion (MJF)

Multi Jet Fusion (MJF) produces strong, isotropic nylon parts with fine features and smooth surfaces, ideal for functional prototypes and short-run production batches.

Overview

Multi Jet Fusion (MJF) is a powder-bed plastic 3D printing process that uses inkjet-deposited fusing agents and infrared energy to create dense, isotropic parts. It excels at producing functional nylon components with good surface finish, fine detail, and consistent mechanical properties in all directions. Parts typically come in a uniform gray or black, with optional dyeing and basic finishing.

Choose MJF for functional prototypes, fixtures, and low- to mid-volume production parts where strength, accuracy, and repeatability matter more than high gloss cosmetics. It handles intricate geometries, internal channels, and nested part layouts efficiently, making it cost-effective for trays of small parts. Tradeoffs include a relatively limited material set (mostly nylon-based), moderate dimensional tolerances compared to machining, and porous surfaces that may require sealing for fluid handling or airtight applications.

Common Materials

  • Nylon PA12
  • Nylon PA11
  • Glass-filled PA12
  • Nylon PA12 with carbon
  • TPU 88A

Tolerances

±0.010" to ±0.015"

Applications

  • Functional snap-fit housings
  • Jigs, fixtures, and assembly aids
  • Manifolds and lightweight ducting
  • Custom brackets and mounting hardware
  • Robotics and automation components
  • Short-run consumer product enclosures

When to Choose Multi Jet Fusion (MJF)

Pick MJF for nylon parts that need good strength, near-isotropic properties, and consistent quality across batches, especially with complex geometries or many small parts. It fits functional prototypes, fixtures, and low- to mid-volume production where injection molding tooling is not yet justified. It also works well when you want nested production of many different parts in a single build.

vs Fused Deposition Modeling (FDM)

Choose MJF over FDM when you need better dimensional consistency, finer features, and more isotropic mechanical properties across X/Y/Z. MJF also scales better for trays of many small parts and yields more uniform surface finish without visible filament lines.

vs Stereolithography (SLA)

Choose MJF over SLA when functional strength, toughness, and temperature resistance matter more than ultra-smooth, glossy surfaces. MJF nylon parts generally hold up better under load, in snap-fits, and in real-world testing where brittle resins can crack or creep.

vs Selective Laser Sintering (SLS)

Choose MJF over SLS when you want faster turnaround on batch builds, more consistent part-to-part properties, and typically smoother surfaces with crisper fine details. MJF is also well-suited when you need repeatable production runs using the same material and print settings across time.

vs Digital Light Processing (DLP)

Choose MJF over DLP when you prioritize mechanical robustness, impact resistance, and functional testing over very high-resolution surface detail. For fixtures, housings, and mechanical parts in nylon-like materials, MJF offers more durable, less brittle components than most DLP resins.

vs PolyJet

Choose MJF over PolyJet when you need durable, production-like plastic properties rather than aesthetic multi-color or rubber-like concept models. MJF parts usually have better long-term stability, mechanical performance, and lower part cost for batches of functional components.

Design Considerations

  • Maintain minimum wall thickness of ~1.0–1.5 mm for structural walls and increase thickness for large flat spans to reduce warping
  • Avoid large solid masses; use internal lattices or ribs to save material, reduce cost, and improve thermal behavior during printing
  • Design powder escape holes (≥3–4 mm diameter) for enclosed cavities so technicians can remove unfused powder
  • Specify critical dimensions and mating interfaces clearly; plan to post-machine tight-tolerance bores, shafts, and sealing surfaces if you need better than standard MJF capability
  • Add generous fillets at internal corners and around bosses to reduce stress concentrations and improve print reliability
  • Group many small parts into a single build volume and keep Z-height compact to reduce per-part cost and lead time