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DMLS vs SLM - What is' the difference?

Written by Abigail    2022-05-13

Laser technology, computer technique, mechanical engineering technology have been flourishing since the 1990s. 3D Printing, also known as additive manufacturing, was thus emerging. There are lots of different technologies in 3D Printing, while metal 3D Printing attracts most attentions in the industry. However, metal 3D Printing can be divided into multiple parts. In this article, we will learn two metal laser 3D Printing technologies, DMLS and SLM.

 

Part 1. Brief introduction of 3D printing, DMLS and SLM

When we print a document, what we get is the text or 2D images on paper, whereas 3D Printing is to print 3D objects by adding material layer by layer according to 3D designs. Besides, printing 2D document uses carbon powder as printing material. 3D Printing uses various material to shape an object, such as liquid, plastics, metal, etc. Take metal 3D Printing as an example, it uses metal powder to produce 3D objects.

Direct Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM) are types of metal 3D Printing. To be specific, both DMLS and SLM are using laser energy to add metal powder together rapidly. Featuring high energy density, laser light can manufacture metal parts directly which is considered difficult to realize. DMLS and SLM can manufacture complex structure metal parts with various printing materials, such as titanium alloys, super alloys, iron-based alloys, aluminum alloys, refractory alloys, amorphous alloys, ceramics and gradient materials, etc., and have applied in aerospace, automobile, and medical industry.

3d printing, dmls and slm

Image Source: zeal3dprinting

Part 2. What is DMLS Technology

DMLS, also known as Direct Metal Laser Sintering, is a type of metal 3D Printing technology that uses a high-energy laser light to melt the metal powder directly, and solidify the fused materials layer by layer in order to produce parts with high density.

There are two ways to lay metal powder for DMLS Printing, coaxial powder feeding and roller powder feeding. The coaxial powder feeding technology is suitable for the manufacture of objects with a layer thickness of more than 1mm and large metal parts. While roller powder feeding is suitable for small parts manufacturing. However, DMLS manufactured parts are prone to be spheroidized and thermal deformation during the manufacturing process. The spheroidization phenomenon is a deformation process of the interfacial tension between the liquid metal and the surrounding half-solidified part, the shape of the liquid metal surface changes to a spherical surface. Spheroidization will make the metal powder unable to solidify to form a continuous and smooth molten pool after melting, so the formed parts are loose and porous, resulting in printing failure.

In order to solve the issue of spheroidization phenomenon, we can use multi-component metal powders with different melting points for DMLS parts. The multi-component metal powder solution is generally composed of high melting point metal, low melting point metal and some additive elements.

 direct metal laser sintering

Image Source: Moulds Asia

Part 3. SLM 3D Printing Service

SLM, Selective Laser Melting, is also one type of rapid prototyping of metal powder, which can directly produce metal parts close to full density. To be specific, SLM 3D Printing is a technology that uses metal powder to be completely melted under the heat of laser light with high energy, then the parts are cooled and solidified layer by layer. In order to completely melt the metal powder, the laser energy density is required to exceed 106W/Cm2. The molding principle of SLM technology is to spread a layer of metal powder on the print bed with a scraper, and then use laser light to rapidly melt the powder according to certain coordinates under the computer-controlled scanning systems, so that the first layer is done, and then the print bed is lowered to the same height as the previous layer deposition thickness, while a new layer of powder is laid for laser scanning processing again. This process keeps repeating until the entire part is formed. If you are looking for more information of SLM 3D Printing, discover more here Introduction to SLM 3D Printing Service.  

 

selective laser melting

Image Source: Aluminium Today

 

Part 4. Comparison

As we have learned the process of both DMLS and SLM, it is not difficult to find out that both technologies are using laser light to fuse and melt metal powder in which the processes are similar. So, let’s see what is the differences between DMLS and SLM.

  1. The process of heating metal powder is different. SLM is to melt the metal powder completely, while DMLS will not melt all metal powder.
  2. Material flexibility for DMLS is better than SLM. Basically, SLM uses single metal powder during printing, while DMLS is being able to use a combination of different metal powder to ensure metal part's mechanical properties.
  3. The process of laying metal powder while printing may be different. As mentioned above DMLS has two ways powder feeding, whereas SLM only has one choice to do so.
  4. The mechanical properties of SLM parts are better than DMLS parts. As SLM is to melt and solidify the material layer by layer completely, it can create parts is about to full density.
  5. The surface finish of SLM parts are smoother than DMLS parts.

 

dmls vs slm

Image Source: H3D

 

Part 5. SLM Printing Service at Wenext

The latest 3D Printing service in Wenext is SLM Printing, which was launched in March this year. With massive experiences in 3D Printing services such as SLA, SLS, ad MJF, Wenext guarantees reliable services in SLM Printing as well. From order, manufacturing, post-processing, delivery, and after sales service, Wenext provides high efficiency and transparency to our customers. We strive to support our clients 24/7. Besides, with high in-house production capacity, self-developed supply chain management systems and instant quoting engine, Wenext delivers online 3D Printing as easy as online shopping. More importantly, we will help our customer to check the SLM 3D model STL files to ensure successful printing. Wenext would like to serve our customer worldwide in a versatile and efficient way.

 

wenext slm 3d printing

 

Please feel free to try instant quoting on our website or contact us hello@wenext.com if you are interested.

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