How to 3d Print Metal

There have been lots of talks about 3D printing metals such as steel and bronze. But the question on people’s minds is, how does it work? 3D printing with metal has lots of applications in the industries such as medical, jewelry, dental, and manufacturing. 

However, most of these applications above are focused on corporate usage only, but companies are working currently on making it possible for many consumers to the 3D print metal on their desktop printers.

Whenever you consider additive manufacturing for business and industrial applications, you’ll notice that 3D printing with metal is the first thing that comes to mind. 3D print metal is one of the most heavily invested and currently the fastest growing technologies in the manufacturing industry. 

It is not only used together with other manufacturing technologies, but 3D printing with metal is capable of producing prototypes and finished products all by itself. Most times, 3D printed objects on metals come out as good as machined parts. 3D print metals are mainly used in prototyping, mechanical engineering, aerospace, specific tools, and more. 

What’s Metal 3D Printing & How Does It Work? 

3D print is an umbrella term for several families of technologies. To simplify it, it is any technology that creates metal objects layer by layer using melting, sintering, and welding which would be called metal 3D printing.

Here’s how it works:

1. The build chamber of 3D print metal is first filled with inert gas (for example argon) which will reduce the oxidation of the metal powder and will be heated to the optimal build temperature.
2. There’s a thin metal powder layer that will be spread all over the build platform and also high power laser scans on the cross-section of the component, which will melt (or fuse) the metal particles together and then create the next layer. Note that every part of the model must be scanned so the part is built fully solid.
3. Whenever the scanning process is completed, the build platform will move downwards by one layer thickness and the re-coater will have to spread another thin layer of the metal powder. These processes will have to be repeated until the whole part is complete.

Whenever the build process is complete, the parts will be fully encapsulated in the metal powder. Note that support in 3D print metal is built using the same material as the part and is always needed to mitigate the warping and distortion that may happen because of high processing temperatures.

Whenever the bin cools down to room temperature, the excess powder will be manually removed and the parts are typically heated while they are still attached to the build platform. This is to relieve any residual stresses. After that, the components will be detached from the build plate through machining, cutting, or wire EDM and will be ready for usage or further post-processing.

How To 3D Print Metal

To 3D print metal, here are the top 3 methods you can use.

1.    Metal binder jetting 

3D Print metal begins like every other printing process, which comes with an awesome 3D design and a slicer that informs the printer where the print head should deposit material. So instead of the plastic being extruded, the metal powder will be deposited or rolled on in a thin layer and a kind of glue binding substance will be removed from the printing head on top of every layer. 

There will be an alternative layer of powder that will bind the fuse together and start to build upwards to create the object. However, some printers have overhead heaters that can allow the layers to dry up and the binding solution allows the powder to melt in places where it was deposited. Note that this process will be repeated until all the layers of the object are completed from the bottom up. Though it can take several hours to complete.

The powder within your design that is not fused will act as a support and it will be separated from the model after it is completed. Once completed, the models will be very fragile; they are filled with air and very porous. But you can place the completed model in a curing oven where they should be kept at 350 Fahrenheit for 24 hours. Note that this heat will evaporate any moisture and harden the glues that are binding the layers of metal powder together. 

However, after they are fully hardened and cooled, they can be filled with material like bronze filler which gives the model enough strength. Though when you don’t fill the inside with another metal substance, the model will still be weak and this is not recommended for creating functional parts. 

The binder jetting method doesn’t allow for color printing, but it works with polymers and ceramic material. This method is faster compared to other additive manufacturing methods, though it can take several hours to complete.  

2.    Powder bed fusion  

The powder bed fusion process method is very similar to the metal binder jetting method except that instead of a binder being deposited to fuse layers of metal powder together, a higher temperature laser or electron beam will be used. 

The laser will maximize the temperature of the powder in places where the design is being built, which will fuse the metal powder and create a solid layer. Note that this process will continue till the entire model is completed. The powder bed fusion method can be performed with one of several different techniques, which includes: 

• Selective laser melting (SLM),
• Selective laser sintering (SLS) 
• Direct metal laser sintering (DMLS)
• Electron beam melting (EBM). 

Below are the difference between all these methods:

• Selective Laser Sintering (SLS): This type uses a laser to fuse layers of metal powder.
• Selective Laser Melting (SLM): This type goes a step further than fusing the powder and can melt the powder. However, it works well-using composites made of one material such as pure titanium or steel vs. many mixed together like most plastics.
• Direct Metal Laser Sintering (DMLS): This type uses the same process as the SLS, but it is used when referring to the process of sintering metal alloys, glasses, and ceramics. 
• Electron Beam Melting (EBM): These layers of powder are fused with an electron beam to melt metal powders. The support structures are needed for this method. Note that this type of method provides a lot of strength to the model due to the temperature of the layers during the fusion.

3.    Directed energy deposition 

This type of method in 3D print metal uses two different types of material, which are metal wire or metal powder. It has a nozzle that moves in multiple directions to extrude wire material or metal powder layer by layer. After the materials are deposited, they will be melted with a laser or electron beam. 

So this process will continue and the object will be built up layer by layer. But this process is normally used to repair and maintain existing metal material, it can also be used to create objects from scratch.

The Advantages of 3D Print Metal

Many people think that CNC machining is capable of almost any kind of work. It's not true. The main advantage of 3D print metal is that it’s almost boundless whenever one considers manufacturing objects with a complex shape. The advantages of 3D print metal include:

• The cost of 3D print metal is cheaper when compared with conventional methods of manufacturing.  
• 3D printers can print complicated details faster than traditional methods of printing.  
• With 3D printing, it’s possible to create precise objects with very small details. However, this depends on the chosen technology.
• With 3D printing, it’s possible to 3D print details in assembly, it will save you time and money
• With more complicated forms, this means that the parts can be lighter in weight without sacrificing strength. This is the reason why 3D-printed parts are high in demand in the aerospace industry. 
• 3D print metal doesn’t waste your material

So we highly recommend 3D printing for intricate parts where other types of technology are inefficient or difficult to use. 

Conclusion

3D print metal processes can be used to print complex, bespoke areas with geometries that the traditional printing methods cannot be able to produce. The material and printing costs of the 3D print metal are very high, so these technologies are not too good for parts that can be easily printed with traditional printing methods.

However, note that the build size of the metal 3D printing systems is limited, and this is because precise manufacturing conditions and process control are needed. Additionally, all already existing designs might not be good for 3D print metal and may need to be altered.