3D Printed - Stainless Steel
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.
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. You can see what this looks like in the image of the ring above.
The minimum recommended wall thickness for Stainless steel is 3.0mm and minimum detail size is 1.0mm. (It may be possible to produce objects with wall thicknesses smaller than 3mm. However, this will only work on parts whose overal size is small and it is very important that these objects are able to support themselves during the infusing process.) Features that extend and converge to a point (eg a cone) should be at an angle greater than 10 degrees.
Because of the post-printing step of firing and infusing the model with bronze, there are specific design requirements.
Nested objects (objects floating within another object), hinged parts, and interlinking parts 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.
Before models are 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.
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.