Metal 3D Printing: The Benefits and Drawbacks of 4 Technologies

As the manufacturing industry continues to accelerate, the introduction and development of new and existing technologies grow with it. That’s where metal 3D printing comes in.

While the advantages of metal 3D printing are extensive, many of them come down to the individual technology used, its benefits and properties that lend themselves to creating a specific part type.

We’ll take a look at four of the leading technologies, their benefits and drawbacks:

• Laser Powder Bed Fusion
• Direct Energy Deposition
• Binder Jetting
• Metal FDM
• Which Technology Should I Choose?

Laser Powder Bed Fusion

Laser powder bed fusion (LPBF) is a technology where a high-power laser is used as a heat source to selectively melt and fuse metal powder on a bed, building a part layer by layer.

Benefits

Arguably one of the strongest benefits of LPBF is that it’s the most widely adopted and established metal 3D printing technique. Considerable research, investment and development have gone into the technology, making it a highly reliable method of metal 3D printing. As it’s the most mature of the technologies, it’s often used as a benchmark to compare other technologies against.

The key manufacturing benefit of LPBF is it can create parts with complex, intricate geometries at high resolution. This is due to the precision capabilities of the laser and the ability to apply thin layer thicknesses when building the part.

LPBF also has fewer post-processing steps and therefore tends to have shorter overall lead times than other technologies. The shorter the lead time of a part, the less downtime businesses may experience due to equipment outages, saving them money.

Not only can LBPF print complex parts, but it can also produce small to large-sized parts with excellent strength, hardness and density properties. In addition to this, a wide range of materials can be used for LPBF, making it a well-rounded technology that can be used for multiple applications.

Drawbacks

Although LPBF is the front-runner in the industry, it doesn’t come without its challenges.

The first — and perhaps most limiting — drawback of LPBF is it’s an expensive technology. LPBF machines can cost over €1 million, making it an unattainable process for many small businesses. However, a solution to this is to work with an experienced metal 3D printing service provider, which has the expertise needed to utilise this technology.

Compared to other additive manufacturing methods — such as DED or BJT — LPBF has a slower build rate, which can reduce productivity. As well as this, more support structures are typically needed which can increase the time spent on printing and support structure removal. 

Direct Energy Deposition

Direct energy deposition (DED) is a process where a focused energy source is used to deposit melted metal — powder or wire — onto a surface where it solidifies, creating a printed part.

Benefits

DED is similar to LPBF in the sense a heat source is used to melt material. The difference is both the laser and the material sit on a single head that dispenses both simultaneously.

As DED distributes the material and laser through one head, it can repair existing parts. This could be a particularly attractive quality for some businesses that may only need small repairs rather than pay the greater expense of recreating a part from scratch.

Another benefit of DED is it can print much larger parts than any other technology. As it uses a robotic arm to print parts, the size of parts it can create is limitless in theory. This creates many opportunities for companies looking to use DED as their method of metal 3D printing.

Lastly, the build rate of DED printers is higher than other technologies. This once again makes it an attractive method for producing very large parts quickly and cost-efficiently.

Drawbacks

Perhaps the biggest disadvantage of DED is the poor resolution of the parts produced. DED deposits materials in thicker layers, meaning that nearly all surfaces require some form of post-process machining, increasing the timeframe and costs. Not only this, but the increased layer thickness also means that fine features will be impossible to achieve.

Similar to LPBF, DED machines are expensive and require more post-processing due to the poor resolution of the printed part.

Binder Jetting

Binder jetting technology (BJT) is a process where a binding agent is deposited onto a bed of metal powder to form a part layer by layer. Afterwards, the part goes through a debinding and sintering process to improve the mechanical properties of the part. 

Benefits

BJT is becoming increasingly popular as the technology advances and more printing materials are introduced. This is due to its ability to print parts quickly and with a very high resolution, without the need for support structures.

Another benefit of BJT is that a heat source isn’t used during the printing process, meaning there is no risk of deformation to the part due to heat transfer. This enables BJT printers to produce parts in large batches, making it highly productive compared to other additive manufacturing technologies.

Drawbacks

As BJT requires debinding and sintering after the initial printing process, these are additional post-processing steps you’ll need to consider when it comes to the cost and lead time of a print job. 

In addition to this, the printed parts shrink during the sintering process. Although this improves density, it can also result in undesired warping effects. The risk of warping is more prevalent with larger volume parts, where the thermal effects of sintering are more difficult to predict.

As with LPBF, the cost of a printer can be high. When producing parts using BJT, the added investment of a solvent debinding system and sintering oven must also be considered.

Metal FDM

Metal fused deposition modelling (metal FDM) is a process where metal filament with polymer binder is extruded through a heated nozzle, melted and deposited onto a surface to form a part. Afterwards, the part is debinded and sintered to improve the mechanical properties of the part.

Benefits

FDM is widely considered the simplest method of 3D printing. Since it uses wire feedstock to print parts instead of powder, it is safer and simpler for operators to handle. In addition to this, the cost of FDM printers tends to be significantly lower than LPBF and BJT printers but the printing material costs are higher.

As with DED, metal FDM applies material directly onto the build plate without using a powder bed. This means that it is well suited for creating hollow objects, as it does not trap excess material inside the structure.

Drawbacks

The main disadvantage of metal FDM is the quality of the parts it produces. Due to the nature of the metal FDM extrusion process, small bubbles and voids are often introduced into the part, resulting in weaker mechanical properties. The surface finish and feature resolution also tend to be lower compared to LPBF and BJT processes.

As with BJT, FDM printed parts require post-process sintering and are therefore susceptible to warping. However, unlike BJT, FDM printing requires the use of support structures in order to print overhangs and complex geometries.

Which Technology Should I Choose?

When exploring the technologies available for metal 3D printing, it’s essential to weigh up the pros and cons and decide which would work best for your business' individual needs. 

Although LPBF is the most popular technology in the sector, that doesn’t mean newer technologies such as DED won’t take over in years to come. Similarly, just because metal FDM is cheaper and quicker, the quality of parts produced using LPBF is far superior.

We also shouldn’t overlook traditional manufacturing techniques. Although metal 3D printing can print complex parts with high accuracy and excellent material properties, it is still more cost-effective to create simple parts in large quantities using traditional techniques. The ultimate aim is for traditional methods and metal 3D printing technologies to work in unison.

Take a Deeper Dive Into the World of Metal 3D Printing

As metal 3D printing continues to revolutionise heavy industry, finding out more about the process, technologies and applications are essential to ensure your company stays ahead of the curve. If you’re looking for a detailed yet digestible resource, why not download our guide by clicking the link below. Plus, you’ll get free access for life.

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