3D Printing Technology: Selective Laser Melting – SLM

Selective Laser Melting, SLM for short, is a metal additive manufacturing method that is also known as Direct Metal Laser Melting (DMLM). It is commonly used interchangeably with Direct Metal Laser Sintering (DMLS) even though the two technologies differ slightly. You can find out more about DMLS 3D printing technology here.

How Does Selective Laser Melting Work?

SLM starts with the build platform covered by a thin coat of laser powder which is deposited using a powder deposition system. After which, a coater arm sweeps over the build plate to evenly distribute the powder. A laser is then used to melt the powder together to build the part up layer by layer. The concept is similar to welding, however, before the start of the whole process, the build chamber is filled with an inert gas to control the atmosphere inside.

What Materials Does Selective Laser Melting Use?

Metals have to be used for this 3D printing technology. However, a wide variety of metals have been developed such as:

• Steel powder
• Copper powder
• Titanium powder

For a more in-depth look at the materials, click here.

Advantages

Wide Range Of Metals Available

Since the development of SLM 3D-printing technology, many metal materials have been developed. This provides different mechanical properties for varying use cases and needs.

Reduced Lead Time

As metallic parts have much higher mechanical strength, a rapid prototype part can be used as a functional part. This reduces the amount of lead time to manufacture the part as compared to traditional subtractive methods.

Complex Structures

SLM allows for complex internal structures to be printed where subtractive methods are unable to reach or too complex to obtain. This allows lattice structures and different optimisation of parts to reduce additional material that are not needed.

Recyclable Material

The powder that has not been melted can be reused which results in lesser powder being wasted. This reduces the cost per part.

Disadvantages

Expensive

The cost of an SLM 3D-Printing Machine is extremely high making it difficult to obtain. Furthermore, if the parts are not optimised, the cost of the part will be high. The removal of the part off the build plate also requires additional equipment. If a desired surface finishing is required, an additional machine is also needed.

Requires Skilled Workers

The SLM 3D-Printing Technology requires skilled and knowledgeable workers in order to optimise the design for the process and to operate the machine with the correct parameters.

Small Parts

The size of the build plate is currently very limiting which constrains the part size.

Post Processing

As previously mentioned, the part must go through a process to be removed from the build plate. Support structures may also be required to be removed which is very time consuming and at certain areas, difficult. Moreover, if a desired surface finishing is required, additional processing must be done to obtain that finishing.

Messy and Handling

If the powder is not managed carefully, it could get everywhere and create a mess. Personal protective equipment is also required when handling the materials and operating the machine.

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