Metal

ExOne offers digital part materialization in several metals and metal alloys, including:

  • 316 Stainless Steel Infiltrated with Bronze
  • 420 Stainless Steel Infiltrated with Bronze (Annealed & Non-Annealed)
  • Bronze
  • Iron Infiltrated with Bronze
  • Bonded Tungsten

Additional material systems are currently in development, and partnership opportunities are available for specific materials. Please contact us with your requirements. The 3D printing process in metal includes printing, curing, depowdering, sintering, infiltrating and annealing.  

Printing
See how the metal printing process works with this video

Curing
After printing, the build box containing the completed piece or pieces is removed from the machine and placed into an oven for curing of the binder to produce green strength for handling. Depending on the mass of the component(s), the curing operation takes 6-12 hours.

Depowdering
After curing, loose metal powder is vacuumed out of the build box. Air is used to dislodge any loose powder from the part. The excess metal powder is recycled. The part is fragile, but can be handled.

Sintering
The part(s) are placed in a graphite crucible, surrounded by support media, and placed in a vacuum furnace for one 24-36 hour cycle of sintering, infiltrating and annealing. Sintering is performed at about 1100°C to burn off the binder and metallurgically bond the metal particles. After sintering the component is approximately 60% dense.

Infiltration
Infiltration is performed to increase part density to approximately 95% by filling in all remaining voids between the metal particles. Bronze, typically, is wicked into the component through a stilt which is printed into the component and removed after processing. 

Annealing
The final step is to gradually cool the furnace to anneal the part. Annealing lowers the tensile and yield strength, making the part less brittle for post machining such as milling, drilling and tapping operations. The component can also be welded and soldered.

Finishing
After processing, the finish of the component is about a 600 μin Ra (15 μm Ra) with small printing lines remaining visible. Bead blasting improves the finish to approximately 300 μin Ra (7.5 μm Ra). Barrel finishing can improve external surfaces to a 50 μin Ra (1.25 μm Ra). Hand polishing, plating, and anti-corrosion treatments are also available. 

Available Finishes
  • Raw Polished 
  • Gold Plated 
  • Nickel Plated 
  • Antique Bronze Patina 
  • Medieval Pewter Patina
  • Damascus Patina
  • Wheat Penny Patina

Properties 
View 420 SS Material Data Sheet