No materials are more important in the industry than metals. The development of various production methods for metals and their alloys has been the main driver for several industries.

That development trend hasn’t slowed down a bit. Engineers today are still employing new production methods to cope with the changing demands of the industry.

One of the new production methods that have arisen out of this demand is Metal 3D printing or additive manufacturing.

3D printing first came about in the late 1970s as a method of creating functional and aesthetic prototypes with a limited range of materials.

Due to advancements in its technology, we can now 3D print metal parts. Metal 3D printing is slowly evolving from a prototyping method to a production method for end-use metal parts.

In this article, we are going to dive deep into metal 3D printing. We will explore what the technology can do and how long it still has to go.

Most importantly, we are going to show you how you can take advantage of metal 3D printing technology in your business. So, let’s start with the definition of 3D printing.

What Is 3D Printing?

3D printing or additive manufacturing is the creation of solid three-dimensional objects from a digital file. The digital file – usually a 3D model or a CAD file- is used in tandem with a 3D printer to create a solid object layer by layer.

There are many metal 3D printing processes available. Metal additive manufacturing processes include FDM(Fused Deposition Modelling), DMLS(Direct Metal Laser Sintering), and SLM (Selective Laser Melting).

Cheap desktop and tabletop metal 3D printers use FDM(Fused Deposition Modelling) technology. Higher-end machines use  SLM, DMLS, and Binder jetting technology.

In this article, we are going to be focusing mainly on SLM, DMLS and Binder jetting. These technologies are the ones mainly used for metal 3D printing in the industry.

How Does Metal 3D Printing Work?

Like all production methods, the metal 3D printing process comprises three stages: The design stage, the production stage, and the finishing stage.

Let’s look at how all the stages work:

√ The Design Stage

The metal 3D printing process starts with the 3D model. The product engineer and the designer use a CAD application like SolidWorks or Inventor to create the metal part’s design.

During the design process, they select the appropriate metal for the component. Also, they specify the finishing processes the part is going to go through.

A crucial part of the manufacturing process is adding supports for the model. These supports help prop overhanging and complex parts up during the printing process.

Although, some manufacturing methods like Binder Jetting do not require supports.

After running various tests on the 3D model to prepare it for production, they move to the next step. The next step in this process is the model’s Slicing.

Slicing involves dividing the 3D model into many 2D layers and combining them into a .stl file. A software then generates a tool path for the printing tool from the 2D layers. The tool path is known as the GCODE.

The GCODE file is the final output that goes to the 3D Printer. It controls the motion of the printing tool.

√ The Printing Stage

There are three main processes for 3D printing high-quality metal parts. These processes are:

• SLM(Selective Laser Melting)
• DMLS (Direct Metal Laser Sintering)
• Binder Jetting

Let’s examine each process one by one:

1. Selective Laser Melting (SLM)

Selective Laser Melting(SLS) is an additive manufacturing method employed with metals. It entails using a laser as a power source to melt a powdered form of the metal forming layer by layer until the structure is complete.

Step 1:

The process starts in a sealed chamber filled with inert gas. This inert gas can be Argon or Neon. The inert gas protects the part from adverse effects of the atmosphere.

Step 2:

In the machine, there is a chamber filled with powdered metal or the base material for the parts. The powder is spread out evenly over a platform called the build plate. This plate is movable.

*Recall that we said the 3D model is compiled into a series of co-ordinates for the printer. A single slice of the model is called a layer. A layer in SLS printing is typically 20 – 50 micrometers thick.

Step 3:

Next, the laser selectively melts and fuses a portion of the powdered metal on the bed in the shape of the 2D layer. After melting the part, the build plate goes down the height of one layer, and another coat of powder goes over the build plate.

Step 4:

The machine repeats the process for the next “2D slice”. The laser forms the next layer on top of the first one, welding both together in the process. The process keeps going on a layer by layer until the entire model is complete.

After the model is complete, the engineer removes the parts from the build volume and dusts the excess powder off it. Further finishing processes can now be done on the component. We’ll bring you more on that later.

2. Direct Metal Laser Sintering (DMLS)

The process for 3D printing metals with DMLS is similar to that of SLS printing. The only difference is that while in SLS, the metal melts to fuse, in DMLS, the metal is only sintered.

The sintering process fuses the metal powder into a single mass without melting it. This process takes considerably less energy than SLM printing.

Also, while SLM prints mostly metals, DMLS is more suitable for the alloys and superalloys of metals.

3. Binder Jetting

Binder jetting is another additive manufacturing process used for making metal parts. It uses the same powdered metal with an adhesive called a binder to create the metal part. Let’s take you through the process.

Step 1:

The binder jetting machine uses a build platform similar to that of the SLM process. The powdered metal is spread out in a thin layer over the build platform by a recoater blade.

Step 2:

A print head deposits the binder over the powder layer in a pattern similar to that of the 2D slice. The recoater blade deposits another layer of material over the binder. As a new layer of powder goes over the previous layer, the powder glues together on the places containing the binder.

Step 3:

The powder around the bonded parts holds them in place. The build plate drops, and the entire process is repeated layer by layer until the part is complete. After this, the machinist removes the part and blows the excess powder off it.

Binder jetting is more economical than the other two methods. However, it requires more time for post-processing.

√ Post Processing And Finishing Stage

After 3D printing a metal part, it has to go through some finishing processes. The finishing processes depend on the type of printing technology used:

Let’s take a look at some of the finishing processes for the various technologies:

1. SLM and DMLS

Immediately after printing, the first thing done is to remove the supports. After that, the parts are heat-treated to relieve internal stresses set up in them during printing.

The sintering and melting process often produces rough surface finishes. We can improve that by bead blasting, polishing, and other methods.

After that, the parts can undergo machining to increase accuracy, maintain tolerances, etc.

2. Binder Jetting

The post-production process for binder jetting can be a bit extensive. Due to the binder in the materials, it has a porous structure. To make it denser, we use two main methods:

• Infiltration: After printing, the material is put in a furnace to burn out the binder. After burning the binder, the technician fills the porous spaces left behind by the binder with bronze to seal them up.
• Sintering: In this process, the engineer places the parts in a high-pressure furnace. The heat burns the binder out while the pressure bonds the structure together to reduce its porosity.

After this, a machinist can use conventional finishing methods like CNC machining to increase the surface appearance, accuracy, etc.

What Metals Can We  3D Print?

A wide range of metal powders is available for metal 3D printing. They range from pure metals to alloys and even precious metals.

The materials include Titanium, Titanium alloys, Aluminum, and its alloys, Nickel Alloys like Inconel. Also, precious metals like Gold, Silver, etc.

All the above metals can be 3D printed with SLM and DMLS processes.

Applications Of Metal 3D Printing

Metal 3D printing is quietly becoming a popular method of production. The advantages it offers in speed and customizability are giving it an edge over more established manufacturing techniques.

Let’s look at some fields that employ 3D printing:

1. Aerospace Industry

Metal 3D printing is gaining popularity in the Aerospace industry. Complex parts that usually take months to produce and assemble are now being 3D printed with ease.

To reduce costs and lead times, companies are now seeing the light and heavily using it. For example. GE is currently using metal 3D printing to reduce the costs and weight of its rockets. Another American company, Relativity, is also making headlines with its 3D-printed rockets.

2. Automobile Industry

The automobile industry is another field currently investing heavily in 3D printing technology. Companies like Koenigsegg, Ford, and even Volkswagen are already using 3D printing to create parts in their assembly lines.

3. The Medical Industry

The medical industry was one of the earliest adopters of 3D printing technology. It adopted the customizability offered by 3metal D printing to create lightweight prosthetics for patients.

Now though, the direction is taking a different turn. Metal 3D printing is now being used to manufacture surgical implants for patients using materials like Titanium. This is a big and very exciting advance in medicine.

The above industries are just a small subset of the industries using 3D printing. Many more are also employing it to great success.

Technical Specifications of Metal 3D Printing

Let’s look at some of the technical specifications of Metal 3D printing.

√ SLS And DMLS Printing Specifications

• Dimensional Accuracy: ±0.1mm
• Build Volume: Up to 500 x 280 x 360mm
• Layer Resolution: 20 – 50μm
• Support: Supports needed
• Minimum Wall Thickness: 1.0mm
• Porosity: 0.2% – 0.5%
• Surface Roughness：12- 16μm(Before post-processing)

√ Binder Jetting Specifications

• Dimensional Accuracy: ±0.2mm
• Build Volume: Up to 800 x 500 x 400mm
• Layer Resolution: 35 – 50μm
• Support: Not needed
• Minimum Wall Thickness: 2.0mm
• Porosity: 3% – 10%(After Sintering and infiltration)
• Surface Roughness：6μm(Before post-processing)

How Much Does Metal 3D Printing Cost?

When it comes to metal 3D printing, it’s difficult to give a standard price quote or rate. The cost differs from project to project.

We’ve compiled a few factors that influence the price of the final part to give you an idea of what goes into the final quote:

√ Material

The metallic powder is one of the factors that contribute the most to the cost. A kilogram of stainless steel powder can cost up to $500. The model’s price can rise quickly, especially if the part has many printing supports (SLM and DMLS).

To reduce the cost, designers should consider designing and printing parts with fewer supports. Reducing the infill rate of the internal structure(using a lattice) can also reduce the cost.

√ Complexity Of the Part

The part’s complexity also plays a role in the final cost. Complex parts often need more support structures while printing. More supports directly translate into more powder usage.

The handling and post-processing costs of complex parts are also high. Due to their nature, more care has to be taken when handling and working with them.

√ Post-Processing Costs

The treatments the parts need after printing also add to the costs. SLM and DMLS parts often require heat treatment, surface finish, and machining processes before they are ready for market.

The post-processing costs for Binder jetting parts are higher.  Metal components made with Binder Jetting need additional processes to remove the binder from their structure.

Advantages of Metal 3D Printing

Metal 3D printing brings plenty of advantages to its industry adopters. Let’s look at some of them.

• Due to the speed 3D printing offers, it reduces lead times and shortens the product design cycle.

• It can be used to manufacture parts with complex internal geometries that other manufacturing methods cannot produce.

• The internal structure of metal 3D printed parts can be modified, leading to lighter weight parts that retain their full strength.

• A wide variety of metal powders are available to create parts depending on what you need.

Limitations Of Metal 3D Printing

Although metal 3D printing has gone far, there are still some limitations to what it can do. Let’s have a look at these barriers:

• It is not suitable for mass-producing parts because the material and manufacturing costs remain prohibitively high.

• 3D printed metal parts often require additional processing before they can be used successfully.

• The build volume offered by Metal 3D printers can be too small for some projects.

Customer’s Guide To Selecting A Metal 3D printing Vendor.

As we said, metal 3D printing is exploding in popularity. If you think the cost of a 3D printer is too much for your business, there are many metal 3D printing services available to take care of your rapid prototyping or low-volume projects.

However, before you send off your designs to just any vendor for production, there are some things you should consider. Let’s go through these things:

1. Cost

The cost is an important factor to watch out for. As we mentioned, it can cost a lot to 3D print a metal part, especially if it’s a complex one.

The best thing to do is to choose a machine shop that can offer you a balance between cost and quality. This can go along way in staying helping the project stay under budget.

2. Support Staff

Metal 3D printing requires expertise right from the design stage through to the finishing stage. A great team will not only help you optimize your design for printing, but they’ll help you get your work done in rapid time. This can help immensely in keeping the costs down.

3. Industry Experience 

Finally, always use a vendor that has experience in working in your particular field. Experience in the field often helps in knowing the right requirements, standards, and specifications needed.

Also, more often than not, they will always have the right equipment needed for the project.

The Conclusion

As we’ve seen, metal 3D-printing is going to play a big role in the future of rapid prototyping manufacturing and low volume manufacturing. Here at RapidDone, we run our business with one eye on the future. We are constantly looking to see how future technology can benefit our customers.

As one of the earliest adopters of metal 3D printing technology, we have the experience and skills to bring your project to life. Also with our top-notch range of machines, we can get the job done for you at the best cost possible.

So, contact us, send your designs in, and let’s help you bring that project to life.

FAQs

Q1. Which metal 3D printing process produces the strongest parts?

A: SLM and DMLS printing generally produce the best parts. Metal parts made with binder jetting have a highly porous structure because of the binder used to make them.

Q2: Can 3D printing be used to mass-produce metal parts?

A: Metal 3D-printing is best suited for low-volume high-speed production. Mass-producing metal components with 3D-printing remains very costly.

Q3: How do 3D printed Metal parts compare with regular metal parts?

A: If we compare metal 3D-printing with conventional production methods, like die casting. The 3D-printed metal parts often have higher strength, hardness, and flexibility.
However, they have less fatigue stress, and their surfaces after production are rougher.