Different types of 3D printing technologies continue to drive innovation wheels in the design, manufacturing, and distribution sectors. If you are an industry player, your understanding of how these technologies work and differ from each other is critical. In this post, we compare Selective Laser Sintering(SLS) with Direct Metal Laser Sintering(DMLS), or simply SLS vs. DMLS.
In the post, we compare their advantages and disadvantages. We also expound on their various industry applications.
Finally, to guide you in your decision-making process, we provide you with a summary table that compares the similarities and differences between these two 3D printing processes.
1. SLS vs. DMLS – General Overview
SLS and DMLS are additive manufacturing processes and are common types of Laser Powder Bed Fusion (LPBF) Technology. How do they work and what makes them different or similar to each other? Let’s find out!
1.1 SLS 3D Printing Process
SLS is one of the most widely used additive manufacturing processes in which your selected plastic powder material is heated and with the help of a focused laser beam, particles are atomically bound together layer-by-layer to form a solid component.
In simple terms, the sintering process does not involve the melting of the powder materials. Instead, it uses heat and pressure to combine the particles to form a solid product.
SLS 3D printing is usually associated with printers that work specifically on plastic powder materials.
Interestingly, you can still use the SLS 3D process to print some parts by combining plastic powder with certain metal powder.
For instance, Alumide which is a combination of Polyamide(nylon) and aluminum particles can be used to produce sturdy prototype parts, illustrative models, or functional components.
1.2 DMLS 3D Printing
In terms of the process, DMLS also referred to as Direct Laser Metal Forming(DLMF), or Laser Metal Fusion (LMF), works based on the same technology as SLS, but uses selected metal powder which has to be melted by high-power laser then fused to form solid parts.
So, for DMLS printing, you will require a special 3D printer capable of printing your desired metal powder materials.
1.3 SLS vs. DMLS – Common Powder Materials
1.3.1 Common SLS Printing Materials
The most popular materials to consider for your SLS 3D printing processes include:
- Nylon or Polyamide 11
- Nylon/Polyamide 12 -CF/GF
- Polyetherketoneketone (PKK)
- Polypropene/Polypropylene (PP)
- Polyamide & Aluminum particles – Alumide
- TPU (Thermoplastic Polyurethane)
1.3.2 SLS Material Characteristics
The commonly used SLS materials are known for their durability, and desirable mechanical and thermal properties. They are also resistant to a wide range of chemicals.
1.3.2 Common DMLS Printing Materials
Some of the most common powder materials you will find suitable for your DMLS 3D printing project include
- Stainless Steel
- Titanium
- Aluminium
- Nickel Alloy
- Inconel
1.3.3. DMLS Material Properties
You will notice that the most commonly used metal materials for the DMLS 3D printing process have properties that suit the applications of the printed parts.
These properties include but are not limited to:
- Hardness
- Ductility
- Stiffness
- Heat Distortion Temperature
1.4 SLS vs. DMLS 3D Printers – Material Specifications
No single SLS 3D printer or DMLS printer works with all their powder materials.
For instance, certain SLS 3D printers will only be suitable for specific types of plastic powder materials.
Likewise, different DMLS printers are designed for specified types of materials
1.5 Related 3D Printing Comparisons – SLS vs. SLM & DMLS vs. SLM
Some of the related 3D printing processes you must not confuse with each other are SLS vs. SLM and DMLS vs. SLM.
To easily distinguish these printing methods, simply take note of the following:
- As already described, for SLS and DMLS, the powder materials (plastic and metal powder respectively) are simply atomically fused layer-by-layer by laser energy. No prior melting of materials is required.
- In Selective Laser Melting(SLM), metal powder is first heated to its melting point by a high-energy laser before being fused to form a solid product.
2. SLS vs. DMLS – Advantages & Disadvantages
2.1 Advantages of SLS In Comparison to DMLS
2.1.1 Versatility of Products & Materials
SLS provides you with higher product versatility as it can produce a wide range of products compared to DMLS. It also allows for the creation of more complex components, or prototypes than DMLS.
Further, SLS allows you to use a wider range of powder materials such as plastic, ceramics, and metal
2.1.2 Cost-effective production
SLS vs DMLS cost, is more cost-effective when it comes to the production of complex components or prototypes. In terms of equipment, SLS 3D printers are much cheaper compared to 3D DMLS printers.
Further, SLS uses much cheaper materials. It also does not require additional tooling expenses, and its post-processing cost is much lower.
2.1.3 Faster Production Capability
While there is no remarkable difference in the printing speed of SLS and MDLS, the overall production capacity of SLS is faster.
This is because of its lower heating requirements. Because it requires no printing support, and post-processing requirements are not complex, your production time will be used more efficiently.
2.1.4 Higher 3D Print Volume
With SLS 3D printing, you get a higher 3D print volume than DMLS. This means you can produce much larger products or components than you can achieve with DMLS.
2.1.5 Multiple Color Printing | Coloring & Dyeing Ease
Because SLS involves heating and binding of particles together, you can easily configure it to print different colors on different parts of a single component being produced. This is not possible with DMLS.
Because SLS produces porous parts, dyeing and coloring of your printed products can be done more effectively.
2.1.6 No Printing Support Required
When using SLS, you do not require any 3D printing support. This is because the unused powder within the printing chamber provides adequate support for the parts being printed. And so, this saves you production costs.
2.2 Disadvantages of SLS
SLS printing has the following limitations in comparison to DMLS:
2.2.1 Plastic Components Limitation
Choosing to adopt the SLS process limits you to only using plastics as the main printing material. And so, due to this limitation, the range of products you can produce or create is also limited.
2.2.2 Less Stronger & Low Heat-resisting Parts
Components made through SLS are less strong compared to DMLS. This is because of the nature of the raw materials used which is mainly plastic.
Therefore, produced components are not suitable for applications that demand high precision, high strength, or high-temperature resistance.
2.2.3 Lower Printer Resolution
SLS printing produces components with lower resolutions. Therefore, your produced parts will be less detailed compared to the DMLS process.
2.2.4 Lesser Recyclability of Production Powder
The rate at which you can recycle unsintered powder is lower than in the DMLS printing process. More than 80% of unsintered powder cannot be recycled.
So, this means you will require more powder for your printing projects leading to higher expenditure on production materials.
2.2.5 Produces More Powder Dust
The SLS printing process exposes you to more dust compared to DMLS. This can have negative impacts on either your health or that of your printing machine operator.
2.3 Advantages of DMLS Compared to SLS
Here are some of the key advantages you will derive by choosing DMLS printing over SLS:
2.3.1 Multiple Materials Can Be Printed
Unlike in SLS printing where you will be limited by material choice, DMLS provides you with a wide range of options when it comes to material selection. Therefore, it allows you to produce a wider range of complex components.
2.3.2 Superior Mechanical Property of Components
Because DMLS uses metal powder material, parts produced by the 3D printing process are superior in terms of mechanical strength.
The parts produced are also more dense and homogenous. This is mainly because of the higher laser temperatures and power that are required to melt and fuse the parts
2.3.3 Higher Printing Resolution
Compared to SLS, the DMLS 3D printer can print higher-resolution products. This is more desirable if you are keen on producing components with finer details or with more intricate features.
And so, this makes the DMLS a better option if your project requires a higher level of accuracy with richer printing details.
2.3.4 Higher Recyclability of Used Powder
When using the DMLS printing process, you can recycle 100% of used metal powder material which is not the case with SLS. This is primarily because the unused powder is not exposed to oxidation during the printing process.
And so, in terms of material use, DMLS is a more cost-effective 3D printing technology.
2.4 Disadvantages of DMLS Compared to SLS
Despite its various advantages, DMLS also has its fair share of drawbacks that you must take note of. These include:
2.4.1 Higher Production Cost
When choosing DMLS as your 3D printing option, you must be ready to incur more costs in acquiring its 3D printer and the materials in comparison to SLS.
DMLS printing is also a more complex process and demands higher production energy. So, it is again more costly in terms of power consumption, and based on its maintenance requirements.
2.4.2 Requires Printing Support
Being a complex process, DMLS printing requires that you have support structures in place. The creation and removal of these structures require more time and make the production of parts higher than in SLS.
2.4.3 Only Prints in Metalic Color
With the DMLS product process, your printed components will be only in metallic colors.
This is because the 3D printing technology cannot print your desired colors on different parts of your components.
2.4.4 More Porous Components
Unlike SLS, parts produced by DMLS are more porous compared to other 3D printing processes. This has a more negative effect on components’ durability, mechanical strength, and thermal stability.
2.4.5 Smaller Print Volume
Compared to SLS, the printing volume of DMLS 3D printing is smaller which limits it to the production of smaller parts.
3. SLS vs. DMLS – Applications
3.1 SLS 3D Printer Applications
The following are some of the major sectors and industries where the SLS printing process is applied:
3.1.1 Medical and Healthcare Sector
Selective Laser Sintering 3D printing is used in the medical and healthcare sectors, especially in the dental, orthopedics, and neurological surgery fields.
The technology is widely used for functional prototyping, and production of surgical instruments, tools, implants, prosthetics, orthotics, and anatomical parts among others.
3.1.2 Electronics Industry
SLS 3D printing also has its footprint in the electronics industry where you find it used for the production of a wide range of components such as customized electronic equipment, electronic instruments such as electric saxophones, connectors, and complex enclosures for electronic devices.
3.1.3 Packaging Industry
In the packaging industry, the use of SLS 3D printing is quickly gaining traction, especially in the food production sectors.
For instance, food processing companies use the technology to produce plastic prototype containers as samples for assessment of their products by their target customers.
3.1.4 Military Sector
Certain components of military equipment such as weapons, vehicles, bankers, and other fighting machines have complex parts that are produced using SLS 3D printing technology.
The technology also allows for the production of customized components to suit specialized military applications such as security surveillance.
3.1.5 Automotive Industry
Another area where you will find SLS 3D printing widely used is in the automotive industry. It is mostly used to create chassis prototypes and in the production of complex but low-volume products such as engine or suspension parts.
3.1.6 Tooling & Creation of Patterns
SLS 3D printing technology is embraced by manufacturers in the efficient production of their required production tools such as modular molds, jigs, grips, and fixtures.
The flexibility of SLS printing also allows for the customization of tools or patterns to suit specific need applications.
3.1.7 Aerospace Industry
Another industry where you will find massive applications of SLS 3D printing is the aerospace industry.
Known for its adoption of additive manufacturing, the aerospace industry uses the SLS process to produce prototypes, cabin interior components, and other complex pasts.
3.1.8 Prototyping of Parts & Design of Research Models
Industries including research institutions use SLS 3D printers to produce prototypes for functional testing or to create awareness of their new products.
Research institutions also use the SLS process to create or customize complex models for their various research undertakings.
3.2 DMLS 3D Print Applications
3.2.1 Prototyping of Parts
Various manufacturers or industries use DMLS 3D printers for cost-effective prototyping of complex components that ordinarily, would be more costly to produce with other techniques.
Therefore, product designers use the DMLS process to produce replicas of parts either for testing purposes or when developing new products.
3.2.2 Production of Production Molds
Manufacturers who require metallic molds with intricate details for their production processes find MDLS the most appropriate 3D printing process to embrace.
3.2.3 Heat Control Systems
Industries especially within the energy and power sector use the DMLS 3D printers to produce heat control systems with intricate geometries.
The flexibility of the process allows for the creation of different cooling channel shapes to suit different cooling system requirements.
3.2.4 Manufacturing of Jigs and Fixtures | Tooling Applications
You will find many manufacturers adopting the DMLS printing technology to develop jigs and fixtures for their various production processes.
Further tooling applications such as the creation of complex production molds are made possible by the DMLS 3D printing process.
3.2.6 Production of Air Ducts and Mounting Parts
Another sector where the DMLS 3D printing process is used is the production of ventilation products such as complex air ducts and mounting parts.
DMLS 3D printing can be used to create complex air ducts and mounting parts for enhanced airflow in homes.
The technology is also used to make conformal cooling channels for different mold designs. It allows designers to create parts with intricate geometries that can be easily adapted to suit a wide range of cooling systems.
4. Comparison Summary Table of DMLS vs. SLS
| Comparison Features | SLS & DMSL | |
| Similarities | ||
| Use of Powder Bed Fusion technology | ☑️ | |
| Use Isotropic Materials | ☑️ | |
| Ability to Produce Large Parts | ☑️ | |
| Uses Laser Energy | ☑️ | |
| Production of Complex Shapes | ☑️ | |
| Layer-by-layer Printing | ☑️ | |
| Cooling After Printing | ☑️ | |
| Printing of Parts With Internal Structures | ☑️ | |
| Ability to print multiple parts in one fell swoop /Used for series production | ☑️ | |
| Differences | ||
| SLS | DMSL | |
| Cost-effectiveness, Accessibility, & Maintenance | More cost-effective and easily accessible | More costly |
| Production Volume | 550mm X 550mm X 550mm | 400mm X 400mm X 400mm |
| Physical Properties – Hardness, ductility, & Density | Less superior | Highly superior |
| Printing Powder Material | Commonly use plastic powder | Only uses metal powder |
| Energy Requirement | Lower heat energy requirement. Sintering temperature ranges from 160°C – 200°C | High energy requirement. Uses a high-voltage laser with melting temperatures ranging from 1,510°C – 1,600°C |
| Cooling Rate & Post-processing | Require less cooling duration with minimum post-processing | Demanding in terms of cooling time and post-processing |
| Printing Support Structures | Not required. The unbonded powder supports the printed parts | Required |
| Durable, Flexible, & Lightweight | Yes | Parts are durable but are not flexible or lightweight as in SLS. |
| Multiple Parts Coloring during printing | Possible | Not possible. All printed parts have metallic finish |
| Print Quality ( Resolution) | Higher resolution (100 μ) hence more print details | Lower print resolution (154 μ) |
| Recycling of unsintered Powder | Less than 80% can be recycled | 100% can be recycled |
5. Conclusion
Deciding on which fusion powder bed 3D printing option to choose between SLS vs. DMLS depends entirely on your 3D printing requirements. This is because the two processes have their advantages and both can produce high-quality parts with desired properties to suit various industry applications.
If you have budget limitations but are keen on investing in additive manufacturing technology, then SLS will be your most cost-effective option. With the SLS printing process, you will cheaply produce high-resolution components with complex parts.
However, if your industry application demands parts with complex shapes, intricate parts, high mechanical strength, and enhanced application accuracy, then the DMLS process is your most suitable 3D printing alternative.
