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Understanding The Advancements and Applications of Direct Metal Laser Sintering (DMLS)

Advancements in product design and development have made it easier to develop fresh, effective prototypes. And, it has been interesting seeing how some of these concepts work. 

However, over the years, not many product manufacturing techniques have gotten as much acclaim as direct metal laser sintering. In this piece, we’ll look into what makes this method so impressive and how manufacturers can make the most out of it. 

What is Direct Metal Laser Sintering?

Direct metal laser sintering (DMLS) is a popular form of additive manufacturing technology that is used to manufacture components and parts made of metal. One of the many forms of selective laser sintering (SLS) available, the direct metal laser sintering DMLS process is specifically designed to operate with metal powders, with manufacturers fusing different powder particles together based on layers using a laser. 

DMLS is among the most popular additive methods for developing metal prototypes. It shares significant similarities to the selective laser sintering of plastic resin, but it differs since it is more useful for operating with a broad range of metals. 

It should also be noted that this material is especially useful for making small metallic components and features. With its additive functionality, you can use a direct metal laser sintering machine to reproduce geometries that traditional manufacturing machines will struggle with. Here, layers can be as small as 20 microns, with tolerances on small features also coming in the range of  ±0.002 inches. 

Then, you should note the possibility of adding treatment processes such as solution annealing and hot isostatic processing (HIP) to improve the mechanical properties of the parts created by the DMLS process. With any of these, you can take out any stress that acts as a by-product of the sintering process, giving way for a product that is both reliable and efficient. 

In general, this selective laser melting process is especially valued for its ability to create intricate product geometries as well as functional metal parts that come with impressive mechanical abilities. With direct laser metal sintering, you have a process that is useful across multiple industries, enabling quick and effective product prototyping as well as low-volume metal component production without the need for any of the time-consuming traditional manufacturing processes.

The DMLS Process: How Direct Metal Laser Sintering Works

Now that we’ve gone through the direct metal laser sintering definition, let’s take a look into how the process works and what you should expect to get from it. So, how does direct metal laser sintering work?

In general, product manufacturers tend to take different approaches towards this process. So, there’s no one-size-fits-all approach here. Nevertheless, we at KDM Fabrication tend to follow this order for the direct metal laser sintering process:

  • Initial Part Design: To begin direct metal laser sintering services, you start by creating a digital model of the part you’re looking to create. With Computer-Aided Design (CAD) software and a direct metal laser sintering 3D printer, you’ll be able to create a prototype that works for additive manufacturing, with factors like material properties and support structures being put into consideration.
  • Metal Powder Preparation: Next, you get high-quality metal powders – usually in the shape of spherical particles. It is important to consider the material requirements of your desired part when choosing metal powders, with consideration for metal particle shape and size as you work towards building your final product. 
  • Preparation of Build Platform: Clean up the build platform inside the DMLS machine, then coat it with a thin layer of your metal powder. This layer acts as the initial layer of your modeled 3D object, so it is important that you get it right.
  • First Layer Deposition: For this step, your DMLS machine will spread a particular layer of metal powder across the build platform with the use of a recoater blade. You will have to set the machine’s specifications to determine the layer’s thickness, so be mindful of that.
  • Laser Scanning and Fusion: The powder layer is brought in contact with a high-powered laser beam. In most cases, the beam is made of fiber or carbon. With the data being fed into the CAD controlling it, the beam melts and joins the metal powder particles based on the current layer’s cross-sectional pattern.
  • Solidification and Bonding: During the scanning process, the laser heats the particles to a temperature that is close to melting point. With this action, the metal particles seamlessly fuse together and solidify into one layer.
  • Layer-by-Layer Building: Following the completion of the first layer, the build platform is lowered, making space for the next metal powder layer. A roller applies another layer of metal powder on the first one, and the laser scans the new one. The process is repeated, creating another layer that is joint to the one below. 
  • Cooling and Solidification: Now that all layers are joined, the metal part is made to cool in order to prevent any deformation or warping. It is important here to keep a good eye on the cooling rate to ensure that the metal is properly solidified. 
  • Support Structures: If you’re creating a part with an overly complex geometry or an overhang, then you’d need to add temporary support structures to prevent a collapse of the metal powder during printing. 
  • Printing Completion: Keep up with the layer scanning and fusion process until you’ve managed to print the entire metal object. 
  • Post-Processing: Following the completion of the printing process, you can remove the metal part from the build platform and collect any excess metal powder for reuse. Additional post-processing steps could include heat treatment, surface finishing, and any additional finishing processes that help to achieve the right part appearance and properties.

The Most Popular Materials Used in DMLS

One of the most interesting things about the DMLS process is that it works with a broad range of materials. And, as these materials vary, you will be able to find direct metal laser sintering DMLS 3D printers that can create parts while modeling them. 

Some of the most prominent materials used in this process include:

  • Stainless Steel: Alloys of stainless steel – ranging from 316L steel to 17-4 PH – are very popular in DMLS processes. With their strength and corrosion resistance, they work well for different applications in various industries.
  • Aluminum: You can also see aluminum alloys such as AlSi10Mg, which lend their lightweight build and impressive thermal conductivity to the DMLS process. In applications that require strong mechanical properties and low weight, they work quite well.
  • Titanium: Titanium and its alloys, like Ti6Al4V (also known as Grade 5 titanium), are known for their exceptional strength-to-weight ratio, corrosion resistance, and more. With direct metal laser sintering titanium, you have an easy manufacturing process that yields multiple benefits.
  • Inconel: Much has been said about the impressive temperature and corrosion resistance available in Inconey alloys. With DMLS and Inconel, you can create products that work well in harsh environments. 
  • Cobalt-Chromium (CoCr): Alloys made of Cobalt and Chromium will also offer impressive wear resistance and biocompatibility. DIY direct metal laser sintering can be complex here, but it’s possible.
  • Tool Steel: You can get tool steel materials like D2 and H13 in the DMLS process. Their hardness and wear resistance makes them especially ideal for tooling functionalities.
  • Copper Alloys: in applications that require high thermal conductivity, copper alloys and the DMLS process work like clockwork.
  • Nickel-Based Alloys: We already touched on Inconel. However, it is important to remember that it is not the only Nickel-based alloy available. Monel, Hastelloy, and others in this category can also go well with the DMLS process, offering similar benefits to Inconel.
  • Precious Metals: At the same time, you have several DMLS machines that can work with precious metals like platinum and gold. In the jewelry space, this is especially prominent. 

All in all, you want to keep in mind that material availability will most likely depend on your capabilities and the specific direct metal laser sintering machine you’re working with. Fortunately, we at KDM Fabrication have the perfect toolset for you. 

If you need any tools or information to help your direct metal laser sintering DMLS technology, get in touch with us today.

Possible Considerations for Material Selection 

As you can imagine, proper material selection plays a critical role in ensuring that you get the best out of your overall DMLS process. With that in mind, here are some critical considerations you might want to keep in mind going forward when choosing a material:

  • Mechanical Properties: First, take the mechanical properties required for the specific application into consideration. This means examining factors such as  tensile strength, yield strength, hardness, and more. Any material that meets or exceeds your requirements should be a lock. 
  • Chemical Compatibility: In situations where the part will need to be exposed to harsh environments, then it goes without saying that you need a material with optimal chemical resistance and compatibility.
  • Thermal Properties: Next, you want to keep an eye on the materials thermal expansion and conductivity. You might notice that some applications need materials with high or low thermal conductivity, especially when the need arises to manage heat transfer efficiently.
  • Biocompatibility: This isn’t for every functionality. However, in the medical field, we recommend looking into biocompatible materials that can interact well with the human body.
  • Weight: Depending on the application, weight may be a crucial factor. Choose materials that offer the required strength and properties while keeping the part’s weight as low as possible.
  • Cost: Of course, everyone wants to save money as they work through their processes. So, work within your budget and choose a material that fits into it perfectly. Find out the direct laser sintering machine cost, as well as other prices associated with the process, and work on how to make a cost-effective process across the board.
  • Printability and Processability: Whatever machine you choose would also need to work well in tandem with the specific DMLS machine you’re having. Not every machine can process every material, so be sure that yours is effective enough across the board. 
  • Powder Availability and Particle Size: Before you begin, you want to look into the material and whether it is available in powder form. Just as well, see to it that you have a suitable particle size distribution.  
  • Dimensional Accuracy and Shrinkage: Variations in material also affect their shrinkage levels during the printing and cooling process. So, when choosing, look into the part’s dimensional accuracy requirements and the possible effects of material shrinkage on the end dimensions. 
  • Surface Finish and Post-Processing: You will find that some materials will need more extensive treatment following processing. Consider the possibility of this, as well as any possible costs that might be associated with it.  
  • Design Complexity: Some materials tend to work better with intricate and complex geometries – while others are limited to simple structure developments. Keep this in mind as you work. 

Advantages & Limitations Of Direct Metal Laser Sintering

As it is with every other manufacturing process, DMLS comes with the good and the bad. And, understanding how each can affect you will be important in the long run. Here is a breakdown of the advantages of direct metal laser sintering and where the material falls short:

DMLS: The Advantages

  • Complex Geometry: With DMLS, you’re able to properly fabricate complex, intricate geometries that traditional manufacturing methods might not necessarily be able to handle. 
  • Rapid Prototyping: DMLS also allows for quick iteration and rapid prototyping, reducing the time and cost required to develop and test new designs.
  • No Tooling Required: Unlike what you get with traditional manufacturing processes, there is no need for specialized tooling when you’re working with DMLS. This means that upfront costs tend to be lower in general.
  • Material Diversity: You enjoy a broad range of material compatibility when it comes to DMLS. This allows for more versatile applications across multiple industries.
  • Reduced Waste: Due to its additive nature, the process doesn’t leave much room for waste. You’d find that only the necessary amount of material powder is used for each part.
  • Customization: With DMLS, you get to enjoy  easy customization, meaning that you can produce tailor-made components that meet your specific needs. 
  • Design Freedom: As a designer, you have the creative freedom to innovate and build different parts using DMLS. Think it, and you can build it. 

DMLS: Possible Limitations

  • Cost: For all its benefits, DMLS can be relatively expensive – especially in comparison to  traditional manufacturing methods. And, as you create much larger parts, you’d find that your costs tend to keep rising. 
  • Post-Processing Requirements: Following the DMLS process itself, you’d still need additional post-processing steps to prepare your parts. 
  • Size Limitations: The build volume of DMLS machines can limit the size of the parts that can be produced, making it less suitable for large-scale manufacturing.

All in all, the direct laser metal sintering advantages and disadvantages show that this process has more upside.

DMLS Cost: How Much Should You Pay For This Manufacturing Method?

 For manufacturing processes like DMLs, there is a lot that goes into understanding cost considerations. Some sources peg the cost of a DMLS part at anywhere between $100 and $2,000. However, as a manufacturer, you should remember that your overall cost can be broken down into the following:

Machine and Setup Costs: First, you need to consider the initial investment into a DMLS setup. The direct metal laser sintering machine price, the cost of fitting your workspace, and more will need to be put into consideration, and you still need to pay for calibrating your machine for specific materials and part designs.

Material Costs: After getting a direct metal laser sintering machine for sale, you also need to consider the cost of the metal powders. This will vary based on the material you select, of course.

Factors Influencing Overall Costing

For the general direct laser metal sintering cost, you would need to keep a few important factors into consideration. 

Part Size and Complexity: In most cases, you tend to pay more to print larger and more complex parts. So, part size will have a role to play. 

Volume of Production: As explained earlier, DMLS works quite cost effectively when it comes to low and medium volume production. However, a surge in production volume can lead to an increased cost per part as well.

Post-Processing: Depending on what you’re looking to achieve with the desired finish, you would most likely need to implement post-processing for your DMLS parts. The extent and complexity of this post-processing will have a role to play in determining your overall cost profile.

Design Iterations: If you have to make different design iterations, then you will need to make adjustments to your cost profile as well. This is why we recommend quick prototyping to help cut prices. 

Industries Where Direct Metal Laser Sintering Is Useful

Direct metal laser sintering has become especially popular for its efficiency across multiple industries. And today, the process is being used to provide parts that are used in some of these fields: 

  • Aerospace: With DMLS, aerospace industry participants can make complex, lightweight components like airfoils and other structural components. With its compatibility with intricate manufacturing processes and ability to reduce weight, the process is very vital.
  • Automotive: Vehicle manufacturers can also make use of the process to ensure quick prototyping and to produce light, high-performance parts.
  • Medical and Dental: In the healthcare space, DMLS can help to produce a broad range of items – ranging from orthopedic implants to surgical tools and more. However, it is important to note that this should be done using biocompatible materials.
  • Defense and Military: Whether it’s designing planes or navy equipment, the defense industry has become one of the biggest applicators of this manufacturing process.
  • Energy and Power Generation: In the energy field, where components need to work in harsh environments, DMLS works like clockwork. 
  • Consumer Goods: In the consumer goods industry, we see this process being used to make personalized high-end products like jewelry and even sporting tools.
  • Tooling and Manufacturing: DMLS comes in handy when developing custom fixtures that can be used in different manufacturing processes – from molding to casting and more.
  • Research and Development: Product developers heavily rely on this process for developing prototypes and test parts for tools that can be used in different industries.
  • Agriculture and Heavy Machinery: For developing construction equipment and harvesting machines, DMLS plays a key role.
  • Aviation and Space Exploration: DMLS is used in the aviation and space exploration industries to create lightweight and durable components for spacecraft, satellites, and space vehicles.

As new materials become more available, we expect to see an expansion of the overall applications of this process. And, we at KDM Fabrication continue to lead the line in DMLS innovation. 

Direct Metal Laser Sintering vs. Selective Laser Melting

In terms of relation, there is probably none that comes close to the direct selective laser sintering of metals like selective laser melting. Nevertheless, there are several differences that you should note here. 

The most prominent difference between DMLS and SLM is in the process. For DMLS, the laser heats the metal powder just under their melting point, allowing them to be seamlessly joined. However, in SLM, the laser is set to melt the metal powders entirely, leaving a part with a fully dense and homogeneous structure. 

You also have differences in areas like density and porosity, where DMLS parts usually come with higher porosities due to the drop in temperature across the process. On the flip side, SLM parts are very dense, providing higher mechanical strength and an overall more uniform structure. 

Both processes work with different materials, and their applications are similar as well. However, when making a choice, your desired material structure, as well as the application, should help guide your choice.

DMLS In the Context of Traditional Manufacturing Methods 

Much has been said about the benefits of DMLS. But, how does it really hold up against other manufacturing techniques that are available to product developers? 

Comparison with Subtractive Manufacturing Techniques 

When you compare DMLS to subtractive manufacturing methods, you’re essentially taking two strategies with fundamentally different approaches to component and product manufacturing. 

Process

As explained earlier, DMLS is additive. This means that the process involves building layers on top of each other using a laser. On the other hand, subtractive manufacturing involves beginning with a solid material block and removing this material through processes like drilling or milling until you get the right shape. 

Material Efficiency

Generally, DMLS is more material-efficient than subtractive manufacturing. Since it only uses the materials necessary for the part, you can cut down on waste. 

Complexity

When pointing out the difference between DMLS and SLM, we explained that the former is especially great with complex products with intricate geometries. Subtractive manufacturing, on the other hand, is a bit more limited in this regard. 

Design Freedom

Thanks to its additive nature, DMLS offers more creative freedom for product manufacturers. However, subtractive manufacturing involves limited access to the part, as well as a need to cut materials by block.

Post-Processing

Although they require post-processing, the parts produced via DMLS tend to need less finishing. Subtractive manufacturing will produce near-finished parts, but these will need more post-processing steps.

DMLS vs. Injection Molding and Casting 

Here, we have three different manufacturing processes, each with its own specific characteristics and advantages. 

Process

DMLS is an additive process where parts are created layer by layer. In injection molding, you have a subtractive method where molten material is injected into a mold cavity and cooled to form the right shape. 

Then, there’s casting – also a subtractive process, where molten material is poured into a cavity and allowed to solidify before the mold is taken out. 

Complexity

While DMLS does well with complex parts, both casting and injection molding do better for making simple and relatively more consistent parts. 

Design Freedom

Creative freedom is an area where DMLS does well. On the flip side, you might need to make a few design modifications for casting and injection molding to accommodate the pattern and mold limitations. 

Material Selection

With DMLS, you work mostly with metal powders. However, for injection molding and casting, you work more with thermosetting plastics. It is worth noting that casting is a bit more flexible with material use, as it can also be compatible with ceramics and metals.

Tooling and Setup

In general, DMLS doesn’t require much in terms of extensive tooling – especially when it comes to low-volume production. On the other hand, casting and injection molding will need you to create specific patterns and molds, which can drive up the costs. 

 Surface Finish

You’d find that a DMLS part usually comes with a rougher surface compared to those made with casting and injection molding. As a result of this, you might need post-processing to get the desired surface quality.

Quality Control and Challenges in DMLS

With quality control, you ensure that the parts created via your DMLS process can meet the right specifications and maintain optimal quality. To that end, here are some critical steps to be implemented as part of your overall DMLS strategy:

  • Machine Calibration: It is important to regularly calibrate your machine to ensure that it remains repeatable and accurate. Adjust all necessary parameters, and carry out tests to ensure efficiency.
  • Material Inspection: You also need to inspect the metal powder being used in the process to ensure its quality and suitability. 
  • Build Parameters Verification: Check all build parameters for every part to ensure that they are in line with your design requirements. From scanning speed to layer thickness, check them all.
  • In-Process Monitoring: As the printing process takes place, you also want to keep an eye on all components to reduce the presence of defects or irregularities.
  • Non-Destructive Testing (NDT): CT scanning, X-ray observations, and more ensure that the internal structures are accurate and without defects.
  • Microstructural Analysis: Microscopy techniques can be used to check the parts’ microstructure and ensure optimal grain structure.
  • Traceability and Documentation: For future reference, keep a record of your DMLS build and any post-processing procedures carried out. 
  • Quality Training and Certifications: Finally, see to it that everyone involved in the process is properly trained in quality control standards and procedures. 

Conclusion

Mechanical part manufacturing has grown significantly in the past few years, and innovations in the space have led to groundbreaking processes like direct metal laser sintering. 

At KDM Fabrications, we’re experts in this process and can use it to fabricate just about any part you need. Get in touch with us today, and let us help bring your desired fabrication to life!

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