Metal 3D printing is a unique way of manufacturing products. Wherein direct manufacturing of unique complex parts, facilitating tools for conventional manufacturing technologies end to end-use parts can be produced using this technology by reducing cost and time. This method is also called as SELECTIVE LASER MELTING (SLM) and DIRECT METAL LASER SINTERING (DMLS).
To clarify, here are the few sample pictures of a 3D printed metal parts.
However, this technology provides the flexibility of 3D printing without causing any harm to the mechanical properties of the metal. Hence due to these features, this technology is widely used in the aerospace industry! where very complex parts are required with better strength to weight ratio. We will look into this technology in detail in this blog.
What’s in it for me?
- How does metal 3D printing works
- Characteristics of SLM and DMLS
- Difference between SLM and DMLS
- Common SLM and DMLS materials
- Benefits and limitations of metal 3D printing.
How Does Metal 3D Printing Works:
The basic fabrication for both SLM and DMLS are similar and here is how it works :
Firstly, the oxidation of the metal powder is minimized by fill the built chamber with inert gases most preferably Argon. Then it is heated to optimal built temperature.
Certainly, a very thin layer of metal powder is spread over the platform which is built and a high power laser scans the cross-section of the component, melting (or fusing) the metal particles together and creating the next layer. The entire area of the model is scanned, so the part is built fully solid.
Once the scanning process is complete, the build platform moves downwards by one layer thickness and the re-coater spreads another thin layer of metal powder. The process is repeated until the whole part is complete.
Once the build process is finished, the parts are fully encapsulated in the metal powder. Here the parts are attached to the build platform through support structures. Support in metal 3D printing is provided using the same material as the part and is always required to mitigate the warping and distortion that may occur due to the high processing temperatures.
After the bin cools out to room temperature. The excess powder is manually removed and the heat treatment is given to the removed parts to relieve the residual stress if any. This heat treatment is done when the part is still in the built platform. Then this part is removed from the built platform by wire EDM or machining and this removed part is sent for the post processing.
What Are The Characteristics Of SLM And DMLS:
In both SLM and DLMS the printer process characteristics is decided by the printer manufacturer itself. However, the layer height of the 3D printer varies somewhere between 20 to 50 microns. Above all, this depends on the flowability, particle size and shape of the metal powder. Moreover, the dimensional accuracy that a printer can achieve is approx 0.1 mm the bed size of printer can vary from 250*150*150 mm to as large as 500* 280 * 360 mm.
Above all, the metal powder used in this process is highly recyclable. To clarify, hardly 3 to 4 % of the material is wasted. However, the remaining powder is mixed and topped up with the new metal powder to the printer and the next part is printed.
Giving support to the structure while printing is very very important. So that 3 or 4% waste which comes out is from the support structure itself.
Almost most of the metal SLM and DLMS parts have isotropic, mechanical and thermal properties.
Metal printed parts are more harder stronger and flexible when compared with that of traditionally manufactured metal parts. But these parts are more exposed to fatigue.
Support Structure And Part Orientation:
Support structure is very crucial while printing using a metal powder. As we know that 3D printer prints the parts layer by layer it is necessary to provide the support structure while printing. Due to very high temperature, support structure for metal printing is given by lattice structure.
However, apart from acting as a support platform for the next layer to built upon. It also acts as a heat sink and absorbs heat from the parts allowing it to cool in a much better way. Always an angle is decided before keeping the part to print in such a way that more strength is available to the much critical areas of the design. Moreover, this will help in reducing the material being wasted unnecessarily in creating support to the area where there is no much support required. This will help in reducing the cost as well as the time required for printing.
Above all the cost for this type of printing is very high. The manufacturers always go for the simulations before printing! so that they can predict the behavior of the part during the printing process. Topology optimization algorithms are also used not only to maximize the mechanical performance and create lightweight parts but also to minimize the need for support structure and the likelihood of warping.
Hollow Section And Light-weight Structure :
Unlike polymer powder bed fusion hollow sections are not widely used in metal printing because support structures cannot be removed easily.
Moreover, as an alternative to hollow sections parts can be developed by using cores, cores are processed using different laser power and scan speed, resulting in different material properties.
In order to reduce the print time cores play an important role and they are very useful when manufacturing larger solid section parts these produce parts with high stability and better surface quality. As said earlier that many industries use this technology because of its good strength to weight ratio so to reduce its weight lattice structure is preferred.
What’s The Difference Between SLM And DLMS:
Firstly, we know that 3D printing is an additive manufacturing method SLM, and DLMS are the two kinds of metal 3D printing that belong to the powder bed fusion printing family. Both SLM ad DLMS has a lot of similarities that are in both the technique laser is used to scan and then selectively melt the metal powder particles and then fuse them together by printing layer by layer.
Moreover, the differences between SLM and DMLS is restricted to the fundamentals of the particle bonding process. SLM uses the metal powders with a single melting temperature and will fully melt the particles, while in DMLS the powder comprises of materials with variable melting points which fuse on a molecular level at elevated temperatures.
Certainly, SLM produces parts using a single metal whereas DLMS produces the parts using multiple metal alloys.
To clarify, here there is a small classification provided about various types of 3D printing in a classification tree.
Common SLM And DLMS Materials:
SLM and DLMS can produce parts from large variety of metals and metal alloys from aluminium, titanium, cobalt, stainless steel etc which cover almost every need of the industries from aerospace to medical, even some of the precious metals like gold, silver and platinum can also be processed but it’s a very costly process and its application is very much limited.
A key strength of metal 3D printing is its compatibility with high strength materials, such as nickel or cobalt-chrome super alloys, that are very difficult to process with traditional manufacturing methods.
Here is the list of some commonly used materials provided in the table below.
|Aluminium alloys||Good mechanical & thermal properties Low density Good electrical conductivity Low hardness|
|Stainless steel & tool steel||High wear resistance Great hardness Good ductility and weldability|
|Titanium alloys||Corrosion resistance Excellent strength-to-weight ratio Low thermal expansion Bio-compatible|
|Cobalt-Chrome super alloys||Excellent wear & corrosion resistance Great properties at elevated temperatures Very high hardness Bio-compatible|
|Nickel super alloys||Excellent mechanical properties High corrosion resistance Temperature resistant up to 1200oC Used in extreme environments|
Benefits And Limitations Of Metal 3D Printing:
- For instance, metal 3D printing helps us in producing the very complicated and critical parts which cannot be manufactured using the traditional methods.
- It provides good strength to weight ratio because of the lattice structure being used or even because of the topology algorithms being used.
- Metal 3D printed parts have excellent physical properties and the available material range includes difficult to process otherwise materials, such as metal super alloys.
- The manufacturing cost is very high and is not as simple as that of conventional 3D printing using PLA or ABS so this technique should be used only to manufacture complex parts that cannot be manufactured using conventional manufacturing techniques.
- However, the build size of the metal 3D printing systems is limited, as precise manufacturing conditions and process control are required.
- Existing designs may not be suitable for metal 3D printing and may require some alterations in the design because 3D printing is used to produce some unique parts which cannot be achieved using the conventional methods so it’s good to produce the parts with unique design and difficult to manufacture parts using this technique.
Well by now you might have understood in detail about metal 3D printing its techniques, how to metal 3D print a part, its applications and its benefits.
We will look onto some more interesting manufacturing technologies more specifically about 3D printing in the upcoming blogs.
So here in this blog, we came across what is metal 3D printing how industries are benefited from this technology how we can use it and its advantages and disadvantages. If you want to explore more about 3D printing and want to learn 3D printing from basics about various materials used and its application then you can check out our other blogs as well.
Yes it is strong. It will have same characteristics as that of the conventional metals.
Here you can produce the metals parts at much cheaper price. More complex molds can also be created here.
It was invented in the year 1980s by Charles W.H. HULL
It will cost you around Rs. 37,00,000/- But this is a one time investment.
Yes there are specific printers available particularly for metals. Those are the DMLS printers.
Technically yes! you can print gold using 3D printer! but it will lead to more expensive results.
DMLS stands for DIRECT METAL LASER SINTERING (DMLS).
I am a mechanical engineer very passionate in latest technology and recent advancement in the field of technology and also a active Stock market investor.