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3D Printed - Stainless Steel

 

Material description

Stainless steel objects are printed in a hybrid of stainless steel infused with bronze. This is the hardest of all the 3D materials.

The material retains the dark grey color of stainless steel throughout the model.

Orders using this material generally ship in 2-4 weeks. Find out more.

Technology description

Stainless steel objects are made in a 3-step process:

1) 3D printing in stainless steel - A Prometal 3D printing machine uses an inkjet head to deposit an organic binder onto a stainless steel powder surface. Each layer of powder is adhered in succession until an object is formed. After the printing has finished the object is placed in an oven to cure the binder.
2) Infusion - Objects are taken from the ProMetal 3D printing chamber and excess stainless steel powder is removed. These objects are then transfered into a furnace container with bronze. This is heated in a furnace at a high temperature to infuse the bronze into the porous stainless steel objects. This produces a solid metal object that is a hybrid of stainless steel and bronze.
3) Finishing - The object is bead blasted to smooth the surface after the infusing process.

Note: All metal objects will have an area on them where the metal has been ground to remove a sprue. This is the area where the bronze enters your object and cannot be avoided. This needs to be ground off and polished which may look different to the surrounding printed material.

Design tips

3D Printed metal has some very specific requirements.
GEOMETRY:
The minimum recommend wall thickness for Gold plate depends on the size of your design.

Part dimension (x, y and/or z)Minimum wall thickness (inches)Minimum wall thickness (mm)
0.125in - 3in / 3mm - 76mm0.041.0
3in - 6in / 76mm - 152mm0.061.5
6in - 8in / 152mm - 203mm0.082.0
8in - 12in / 203mm - 305mm0.1253.2

For geometry that is not the main structural support, such as: Extruded lettering, Aesthetic surface details or patterns etc
The minimum recommended thickness is 0.03”/0.8mm

HOLES AND NEGATIVE FEATURES:
All through holes and cut details must have a minimum size of 0.04” / 1.0mm

All negative embossing/indents into the part needs to have a minimum size of 0.03”/0.8mm

Holes less than this value will not be successfully depowdered and will be filled with bronze during the infiltration step of the process.

TEXT:
Text needs to have a thickness of 0.03”/0.8mm
Extruded text should stick out from the surface 0.03”/0.8mm
Text cutting into the part should have a depth of 0.03”/0.8mm

INTERIOR CAVITIES:
Interior cavities must be 0.08”/2mm or greater.
Interior cavities must have an area to allow the unbound powder to be removed.
Minimum size of depowdering hole needs to be 0.06”/1.5mm.
Minimum of 2 holes required allowing for airflow through part.
Larger cavities require more and/or bigger holes.

SPRUE AREA:
All parts require a sprue area where the bronze will enter into the printed part.
Min surface area for the sprue area is 0.06”/1.5mm
Generally the printer chooses the area where the sprue is placed. This is placed in an area that will least affect the appearance of the part. EG for a ring they’ll determine the underside of the ring and use this for the sprue area.

INTERIOR EDGES / CONCAVE EDGES:
Inside corners should be radiused to reduce cracking during infiltration and firing. A minimum 0.03” / 0.8mm radius is recommend though this should be increased as the part size increases to match wall thickness minimums.

KNIFE EDGES:
Edges that come to a point will get blown away during depowdering.
Radius knife edges to 0.03”/0.8mm.

Features that extend and converge to a point (eg a cone) should be at an angle greater than 10 degrees.

PART CONNECTIONS:
Where 2 geometries meet there needs to be a smooth transition from 1 to the other.
Where the connection is not smooth the bronze will not flow through the part correctly.
Even wall thicknesses and transitions are recommended. Areas of material that are different thicknesses will heat (expand) and cool (contract) at different rates. These need to be kept as uniform as possible to minimize the chance of cracking during the stage of the process.

NESTED OBJECTS:
Nested objects (objects floating within another object), hinged objects, and interlinking objects like chains cannot be made with this technique. These floating parts cannot be supported and kept separate while the object is being infused with bronze and therefore would be fused together during firing.

SELF SUPPORTING:
Before models are is infused with bronze they are very fragile. It is very important that objects have enough strength to be self supporting. For example, large, bulky geometries connected with thin structures (like a character with a big head on a skinny neck) could break when the model is being handled before infusion. Your object needs to be designed to adequately support itself during this process.

Tips from other designers

None-set-small
tha says:

http://www.sysax.com/ftpauto/

Added about 1 year ago. ( delete )
None-set-small
Peter says:

how come you can't use aluminum powder instead of the steel powder? Is there a aluminum powder for the 3D Printer?
Will the aluminum powder wick up the liquid Bronze?

Added 10 months ago. ( delete )
500px_logo-01_small
Dan says:

Other services can offer a sintered aluminum material. We do not offer it at this stage.

Added 10 months ago. ( delete )

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