Metal 3D Printing
How Does 3D Metal Printing Work?
Metal 3D printing is a rapidly growing area of technology in the additive manufacturing world. A lot of focus and funding has been pumped into developing a 3d printing service that can create metal parts, due to the fact the properties of metal make it more suitable for high strain engineering/construction uses (when compared to polymers etc.). On this page please find information on the history of 3d metal printing, what is metal 3d printing, the different types of metal 3d printing and the future for metal 3d printing.
During late 1980s, a professor at the University of Texas, Dr. Carl Deckard, developed the first ever SLS machine for polymers. This is one of the first advanced 3D printers and it paved the way for metal printing.
In 1991, Dr Ely Sachs of MIT started developing a new, radical way of creating metal parts, this process is better known as Binder Jetting. Binder Jetting involves ‘gluing’ metal powder together and then heating it up to fuse the metal together.
The first ever patent for laser melting of metals was created in the mid 90s by the Fraunhofer Institute (Germany). This stimulated a lot of interest and lead to the technology being heavily invested in.
During the early 21th Century Metal 3D printing saw a slow down in the growth of innovation. However by 2012, when the patents expired, the industry boomed as other companies were able to compete.
Today we are beginning to see Metal 3D printing becoming more accessible as the technology is cheaper and the results of the printing are high. In 2017, the Metal 3D printing industry was estimated at $720m, and sales for that year increased by 80%.
Different types of metal 3d printing technologies
Powder Bed Fusion
Metal Powder is heated and fused together via a laser
A chamber is filled with an inert gas (to stop the metal oxidising) and it is heated to a temperature only just below the melting temperature of the metal powder.
A thin layer of metal powder is spread over the build platform. A laser scans the surface of the powder to selectively bond the powder particles.
When the area is bonded, the platform moves down a layer and the process repeats until the shape is complete.
Allow time for the print to cool uniformly (so to shrink proportionally). Sometimes post machining, polishing or heat treatment is required.
Built layer by layer by extruding material through a nozzle
Metal extrusion is a 3 step process; printing, de-binding and sintering.
Firstly, the raw material comes in a filament form, the metal will consist of a binding material (polymer or wax). The material will be printed just like any normal FDM polymer.
Once printed you are left with the ‘green’ part, this part is then washed in solvent until all the binder is washed awaye.
The final part then needs to be sintered in an oven to fuse all the metal powder particles together. The parts tend to shrink by 20% during this process.
'Gluing' Metal Powder Ready to be Sintered
A thin layer of metal powder is spread across the build platform. A nozzle then travels over the metal powder and deposits a binding agent (wax or polymer) on areas of the powder which will be bonded together.
When a layer is complete, the platform will drop down a layer, more metal powder is added and the process is repeated until the shape is complete.
The part will then need to be washed in solvent until the binder is removed and it will sintered to fuse the remaining powder particles.
Cost and Benefits of metal 3d printing
Have a look at an overview of the cost and benefits of metal 3d printing
The Benefits of 3D Printing
- Geometric complexity at no extra cost
- Optimised lightweight structures
- Increased part functionality
- Merging assemblies in to a single part
- Simpler manufacturing supply chain
- Excellent material properties
Costs of 3D Printing
- Higher cost than traditional manufacturing
- Limited economies of scale
- A unique set of design rules
- Post-processing is normally requried