I.Materialise Article – An Introduction to 3D Printing For Metal

Today we have a special guest blogger — i.materialise’s Community Manager Roxy Maas will be giving us a basic overview of how gold, silver, brass and titanium are 3D printed.

For those who do not know, Belgium-based i.materialise is one of the big names among 3D printing service bureaus. With over twenty years of experience with 3D printing for product design and specialised knowledge in 3D metal printing, Roxy believes they are in a unique position to provide readers with an “inside scoop” on how the process of 3D printing works with metal, as well as how to best prepare your own CAD work for 3D printing.

i.materialise 3D printed model designed by Bathsheba Grossman

An Introduction to 3D Printing For Metal

Research about 3D printed metals is ongoing, so printing methods vary. This is a general overview of how metals are 3D printed, including some of the most popular metals used for jewelry design: gold, silver, titanium, and brass.

Some Basic Facts About 3D Printed Metal

  • A layer-by-layer printing process called stereolithography is used to make 3D printed metal models.
  • Finished models can be sandblasted, sanded, and polished.
  • Brass models oxidate in a greenish way unless they are plated or varnished
  • Models can be asymmetrical.
  • Allergy-friendly (does not trigger common allergies.)
  • Biocompatible (for titanium)
  • Models do not have thick jagged seams, but might have light marks from the removal of support structures.

Start of the Process

imaterialise_design-montage

The 3D printing process begins when you submit your 3D CAD model (usually an .STL file) to us. You can make such a file using any sort of product design CAD software, such as the ones in our gallery of free software.

There are many different types of CAD software. From browser-based “easy” softwares like JWEEL and Sketchup to fully-featured software suits like 3DS Max, Blender, or Rhino. Any one of them can create a 3D printable piece of metal jewelry.

Engineers cancel files that are not printable. This keeps costs down, and also prevents customers from being charged for a design that cannot print.

If the file is printable, then the technician starts to process it:

Pre-Production Processing Stages

  1. First, the technician orientates the file to ensure it prints in the best way possible.
  2. Second, they add support structures if a model needs them. Support structures prevent models from warping or caving in during the printing process. Adding supports is more or less an automated process, and the cost of support structures are included in the cost of printing.
  3. Third, the technician slices your digital model into paper-thin digital layers, and uploads it to the 3D printer.
horse-3D-print_UST-China
An example of different types of Support Structures, courtesy of 3Ders.org and the University of Science and Technology of China.

Depending on the material you select, there are two basic ways your design can be printed. These basic techniques are currently being used in the field, but we are always researching new and better methods:

Direct Metal Laser Sintering (DMLS)

direct-metal-sintering-diagram

Commonly Used For: Titanium, Stainless steel, and Bronze

DMLS was developed by the EOS firm of Munich, Germany. Similar to the selective laser sintering technology used to make 3D printed plastics from polyamide powder. But instead of using polyamide powder, Direct Metal Laser Sintering (DMLS) uses fine metal powder.

During the printing process, the printer builds your model up layer by layer out of this exceptionally fine, smooth metal powder. During the print, these exceptionally thin layers are sintered and solidified by a laser beam that moves over the powder

Once your model is finished printing, it is then lifted from a bed of fine powder. It is carefully cleaned off using strong gusts of air pressure. And depending on the metal, it is then sintered in an 1300°C oven.

During processing, workers also manually remove and clean away any internal support structures, and this service is included in the cost of your print.

The finished parts have high accuracy and resolution. They require no special tooling, but we offer additional polishing, sandblasting, or sanding for aesthetic reasons.

Lost Wax Casting (LWC)

3d-print-lost-wax-casting-diagram

Commonly Used For: Gold, Silver, and Brass.

A combination of 3D printing and lost wax casting are commonly used to make Gold, Silver, and Brass.

The Lost Wax 3D Printing process begins when your file is submitted to the 3D printer. The 3D printer uses a process called stereolithography to print your design in a wax-like resin, one thin layer at a time.

Support structures are automatically generated and printed along with some models, which keeps them from warping or caving in during the printing process. These structures are removed after the printing process. This is part of the normal printing process, and does not cost extra.

After the support structures are removed, your model is carefully cleaned and prepared for casting.

3d-print-casting-spru-tree
This is one example of what a sprue can look like. They resemble drinking straws, but the sprues used for metal injection molding are usually more sturdy. Photo courtesy of Bluetooth 07 on Wikipedia.

To prepare the print for casting, technicians attach at least one wax sprue to your model. Sprues are tunnel-like passages through which liquid material, such as gold, are poured during casting.

This twig-like sprue is then attached to a wax “tree” of sprues, each belonging to someone else’s model. This bulk processing speeds along the casting process, lowers costs, and results in an even, quality finish. Finally, the wax sprue “tree” is placed in a flask and covered with fine plaster. When the plaster solidifies, it forms a mold used to cast metals, such as gold and silver.

From this mold, your designs are cast.

Because of the production techniques, links or chains cannot be made with this process. Neither can structures such as a ball inside another ball.

3d-printed-post-production-finish
3D printed metals can be sand-blasted, sanded, and polished for a “handmade” or “hand-finished” look. Here is an example of what these different finishes look like for silver.

Basic 3D CAD Design Tips For Better Rapid Prototyping

  • Keep costs down and create a striking piece by designing a piece with a lot of holes or cutouts.
  • Keep in mind that large designs with a great deal of hollow space inside need support structures.
  • After you finish designing something, check your design to ensure it prints. We offer Minimagics as a safe, free software for that purpose.

For more information or any questions for Roxy Maas or the i.materialise team, you can reach her at the I.materialise blog.

3 thoughts on “I.Materialise Article – An Introduction to 3D Printing For Metal

  • 25 August, 2014 at 10:21 pm
    Permalink

    Can the metals be plated? Is stainless infused with bronze? I’m trying to print rings thatbdont varnish or rustbwhen on the finger. I have a nickel plated steel ring from shapeways and bit rusted leaving a stain on my finger in one day. :/

    Reply
    • 26 August, 2014 at 12:02 am
      Permalink

      Hi Mike:

      My answers to your questions in the order you’ve asked them:

      1.) If a given particular alloy can be plated normally, then a 3D metal sintered version of that alloy should be able to be plated. In short, MLS steel should in theory plate as well as ordinary steel.

      2.) 3D printed stainless steel and bronze are separate alloys, if that’s what you’re asking. I don’t know if anyone’s ever tried to alloy the two together, but I don’t imagine it would work that well (given the substantial difference in melting points). But I’ll ask i.materialise just to be sure.

      3.) From my experience working with jewellery, stainless steel is not a particularly good material to use for rings full stop (whether its 3D printed or otherwise). Not only do you have problems with rust, but a stainless steel ring would not “give” the same way soft metals do. This means that as your fingers and joints get bigger with age, the ring will not stretch or accommodate, so it’s only a matter of time before the ring must be removed (or even cut and pried off the finger). This toughness and lack of bendability is also the reason why you cannot to my knowledge effectively resize stainless steel rings.

      Perhaps if you’re looking for that particular greyish colour of metal without issues of rusting, have you considered palladium?

      Jack

      Reply
      • 26 August, 2014 at 12:32 am
        Permalink

        Hey there! Thanks! What i meant as far as stainless is my experience with Shapeways. They use a liquid binder in steel powder and in its green state, then infuse it with bronze. This does two things, depending on the amount of bronze towards the exterior of the item it can be slightly discolored and also can make the metal tarnish. Ive been creating a fidget ring that spins in a track and printing it using my PLA/ABS printer. I want to move it into a metal but dont want it to be crazy expensive. Ill look in to the palladium. What is that like?

        Reply

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