3D Printing process: Selective Powder Deposition (SPD)
Build volume: about 285x248x100mm (or any custom size)
Pourer diameter: 1mm, 2mm (or any custom size)
Layer height: 0.1 to 1.0mm (user configurable in GUI)
Min width of a detail: one pourer diameter
Min height of a detail: one layer height
Powders cost: $2 to $12 per kg.
What metals are supported?
In theory, SPD should work with any metal combinations where the infill metal has lower melting temperature than the powder. So far, we have tried carbon steel, copper-iron, and copper-nickel. All metals that are not oxidizable by carbon oxide (CO or CO2) should work with kilns with air atmosphere. For example: iron, copper, silver, gold, nickel, platinum. Others metals, like aluminum, stainless, titanium, would require more research and a kiln with controlled atmosphere, like vacuum and nitrogen or argon.
What's the shrinkage?
There is no shrinkage. The metal powder is not sintered, but infused with infill metal. So, the size and shape is preserved.
What's the print time?
Print time very much depends on the size and complexity of the object. Rough average would be about 24 hours.
Is there any post-processing required?
Yes. After filling the crucible with the powders, you would need to bake it in a kiln.
What's the baking temperature?
The baking temperature must be in-between melting temperatures of the infill metal and the metal powder. Pure copper infill metal melts at 1084C. Pure iron powder melts at 1538C. So, to print with copper-iron the temperature must be between 1084C and 1538C. For example 1184°C. For carbon steel, the melting temperature of the infill metal depends on the carbon content. There are many resources on the Internet that assist with calculation of melting temperatures of different alloys. For example this one: this one. For example, for carbon steel infill metal with 4.3% carbon, the baking temperature must be between 1147C and 1538C. For example 1250°C. The carbon content of the resulting 3D print is the proportional average of the carbon content of the powder and the infill. For example, with iron powder with apparent density of 3 g/cm3, and infill metal with 4.3% carbon, the carbon content of the resulting 3D print would be around 2.6%
What's the baking hold time?
The hold time should be sufficient for the heat to get to the middle of the crucible and melt the infill metal. The minimum hold time depends on the size and thermal conductivity of the crucible, the mass, and the difference between the melting temperature of the infill metal and your baking temperature. For copper-iron or copper-nickel, with baking temperature of 1184°C, and the crucible shown in the video, the hold time of 2 hours was sufficient.
What kind of kiln is required?
For copper infill metal, your kiln should be able to go above the copper melting temperature, which is 1084C, so most pottery kilns would work. A kiln with programmable digital controller is preferred, because it can be programmed to go slowly though quarts inversion temperature, which is useful if you use a clay crucible. A new pottery kiln might cost you about $1000. A used one you might find for a few hundred dollars on Craig's List, if you look for a while. For carbon steel the minimum required temperature would depend on the carbon content, from 1147C to 1538C.
How can I buy the printer? How much does it cost?
You can order the printer by email. The standard size costs $5000 plus shipping. The price of a custom size printer depends on the size. It's likely that in the near future we'll have a second standard size with print volume of 610x610x380 mm.
Where can I buy the consumables? (metal powders, support powders, infill metal, and crucibles)
You can buy consumables from 3rd parties. The powders should be able to flow though 0.9mm hole. For that, they should be spherical enough, and have particle size of about 50-100 microns. The powders and the infill metal shouldn't have too many impurities. For example, oxygen cause babbles in the printed object. The crucibles should be able to withstand the baking temperature. It's probably better to buy consumables specifically intended for SPD process. We prefer consumables from TriDPrinting.com - please contact them directly. Their phone number is on their home page.