Metal additive manufacturing (AM) is a technology that generates a great deal of excitement, and for good reason. It is capable of many things that have never before been possible with traditional manufacturing technologies. Like any technology, however, it does have its drawbacks. It’s important to look beyond the hype and truly parse out the pros and cons of metal AM. Let’s have a look at some of the biggest benefits and downfalls of this growing technology.

Metal AM Advantages

Additive manufacturing has the ability to produce “near net shape” parts. What does that mean? Near net shape means that the part can be printed at very close to the final size and shape desired, without having to machine away extra material or create additional features such as holes using other tools. This greatly reduces material waste, with the only material used being that needed to print the part and its supports, should the technology require. (Supports anchor a part to the build platform and prevent distortion. They do require some work to remove, and we’ll talk more about them later.)

For technologies like binder jetting, SLS and 3DEO’s Intelligent Layering®, however, no support structures are needed. The surrounding powder provides all the necessary support to print the part while simultaneously maximizing the build volume. And taking things a step further, 3DEO’s Intelligent Layering® is capable of producing net shape for the right application.

Metal AM can print parts with metals that are typically very hard to process using other technologies. These include metal superalloys, or high-performance alloys.

Another benefit of metal AM is that it can produce remarkably complex parts – and there’s no extra cost required than to print simple parts. Machining highly complex parts, in contrast, is much more expensive and difficult. There’s also a limit, in more conventional technologies, to how complex the parts can get – some parts are simply impossible. In additive manufacturing, very little is impossible. Internal channels, delicate overhangs, complicated geometries – they can all be printed if designed specifically for AM.

Additive manufacturing can also produce very lightweight parts. Extremely thin yet strong walls can be created, and structures such as honeycombs or meshes can be used to replace solid sections. In industries like aerospace and medical, for example, this capability has tremendous advantages. The digital nature of additive manufacturing means that parts can be topology optimized, or designed to maximize their performance while minimizing their weight.

The fact that AM can create simple or complex parts at near net shape means a drastic reduction in lead times. Without requiring extra tooling, the time needed to produce a part can be reduced from weeks to days, or even hours. In addition, AM can be used to print assemblies, or joined components, in one single part – no welding or other methods of attaching required.

It’s also easy to change a design that has been 3D printed. If a part doesn’t come out right, it only needs a few tweaks to the virtual design to address the issue, and then a new part can be printed with minimal additional material. No new molds or tooling required, which means no additional setup or molding/tooling fees.

Metal AM Disadvantages

Almost always, metal additive manufacturing does require some post-processing after the part is done printing. The amount of post processing varies depending on the specific technology being used.

As mentioned previously, support structures need to be removed from many metal 3D printed parts. With direct metal laser sintering (DMLS), the part is typically removed from the build platform using a band saw or wire EDM (electrical discharge machining). The supports are then removed using hand tools. Sometimes machining will be used to improve the surface finish.

Rapid heating and cooling of the metal occurs during DMLS as well, which can result in a buildup of internal stresses, so stress relief treatments are required for every build. Sometimes, parts will need to undergo additional heat treatments post-printing to improve properties like hardness, elongation, and fatigue strength.

That’s just one of many metal additive manufacturing technologies. Powder bed fusion (PBF) needs to have excess powder removed from the part, which can be done manually with a brush or compressed air, or through a separate machine. It can be difficult to remove powder from internal channels or cavities. Even this process, however, can be done with minimal waste and in many cases, the excess powder can be recycled.

3DEO’s Intelligent Layering® is a bind and sinter process, which can be subject to part shrinkage without the proper quality control systems in place. With 3DEO’s end-to-end Manufacturing Cloud™, the company combines machine learning, artificial intelligence, software and more to ensure that once a part is qualified, the shrinkage is predictable and highly repeatable. Unlike traditional binder jetting, which can have density issues with finished parts, 3DEO’s material properties and surface finishes are among the highest in the AM industry. Click here to see 3DEO’s 17-4 PH Stainless Steel Spec Sheet as an example.

The metal powders used in additive manufacturing can be tricky. They need to be produced to careful specifications in order to avoid inconsistencies in printed parts, and they must be stored and used carefully to avoid hazards like explosion as well as health problems from inhalation and skin contact.

Another drawback of metal additive manufacturing is that it can tend to be costly, depending on the 3D printing process used. If printing in-house, metal 3D printers have dropped in price since the early days of the technology, but they’re still expensive and so tend to be purchased mainly by large companies or service bureaus. Metal 3D printing also requires a lot of skill and knowledge, which is another reason many companies tend to outsource their metal 3D printed parts to parts producers like 3DEO.

Historically, metal 3D printing is most ideal for small batch production – it can lose its competitive advantage to lower cost structures when getting into larger quantities of parts. As the technology advances, however, larger quantities are becoming more feasible, and 3DEO is one example of a company mass-producing metal 3D printed parts at favorable costs.

With every benefit and drawback, you’re likely to find an exception, which is one of the exciting aspects of a rapidly evolving technology.

The above examples are not a fully comprehensive list of all of the pros and cons of metal 3D printing. There are many different metal 3D printing technologies, each with their own quirks and requirements. These examples illustrate some of the benefits and drawbacks of 3D printing in general. In the future, we may take a closer look at the individual metal 3D printing technologies and their specific needs.

While the hype around 3D printing has claimed that it will completely replace traditional manufacturing technologies, this is not the case. You should think of it more as a complementary technology that can work alongside CNC machining, injection molding, and other methods. In many cases, 3D printing is a fantastic alternative to traditional manufacturing technologies, offering buyers stronger, lighter weight, and more complex parts at a fraction of the time.