What is Additive Manufacturing

Products can be manufactured in a variety of ways and products produced from tantalum are no different. However, some manufacturing processes are far more efficient and effective than others and in some cases, additive manufacturing is the most efficient kind. In this article, we will discuss how additive manufacturing works, how it is used, and how it benefits a number of different industries. 

Additive manufacturing works in the opposite way of subtractive manufacturing. When you use a subtractive process, you start with a solid piece and remove all the material that isn’t needed. Forming automobile and aerospace parts from a large section of steel is an excellent example of this process. Using a mill, workers remove material in a specific way until the desired shape is achieved. 

Additive manufacturing works differently in that a part is built layer by layer. This process allows a precise and often complex part to be created without removing or wasting any material. 3-D printing has become perhaps the most common and well-known example of additive manufacturing. 

Additive manufacturing can be done with virtually any material as long as you have a device capable of manipulating and processing that specific raw material. Common raw materials used in this process include: 

• Metal
• Plastics 
• Ceramics 
• Rubber/Foam 
• Composites of the above 

What Is 3-D Printing with metal powders? 

Versatility and efficiency make 3-D printing with metal powders an incredibly popular form of additive manufacturing. This new technology has allowed additive manufacturing to become more practical than ever before. Previous to this emerging technology, manufacturing parts with complex geometries was tedious and time-consuming, and sometimes impossible. 

Much like conventional printing, 3-D printing is completed using computers and specialized printing devices. The process starts with the use of a CAD, also known as a computer-aided design. Next, a technician uses the program to build the item virtually, setting all of the dimensions and instructions. If the technician is simply copying an existing object, a 3-D scan can replace the design step. 

Once the dimensions and instructions are programmed, the 3-D printer builds the item, adding the selected material layer by layer. Some printers use a laser to fuse all layers together; however, these methods can vary. In addition, 3-D printers differ greatly depending on the materials in use.  

Laser Powder Bed Fusion Method 

The first method is powder bed fusion. In this method, powdered metal is held in a container and sintered together in specific patterns. Sintering is a term that describes the process of fusing particles together with heat or pressure. In the case of 3-D printing with metal powder, this is primarily done with a laser. The laser powder bed fusion (PLBF) printers are able to provide a high level of precision due to the accuracy of the laser control and the microscopic thickness of each layer. 

Layers are usually between 20 and 40 microns. Each print begins with a bed of powder and the laser is used to melt the powder in the designed pattern. The powder bed is re-leveled, covering the melted 1st layer, and the next layer of the part is melted. This continues until the designed part has been completely printed. By using both large and small beams, a remarkable amount of precision can be obtained. Once the part or parts have been fully printed, the remaining loose powder is removed.  

Electron Beam Melting 

The second method introduced here is electron beam melting (EBM) which uses as the name suggests an electron beam to fuse together metal powders one layer at a time. EBM requires a high vacuum atmosphere in order for the high-energy beam to pass from generation to the powder bed. The high vacuum atmosphere enables the use of reactive metals with a high affinity for oxygen like titanium and tantalum. EBM differs from LPBF in that the powder particles are fully melted and the layers are bigger, typically 50 to 100 microns. Parts produced using EBM are generally produced fully dense due to the high-energy beam while parts from other 3D printing technologies may require some post-processing thermal treatment. 

Cold Spray Method 

The third method uses a pressurized spray of particles to coat a substrate material, using layer after layer to build up the part in a specific way. This process may take more time to complete than the powder bed method. Instead of using a laser to fuse the layers together, the metal particles are accelerated to supersonic speeds via pressurized gas, sent through a hose, and undergo plastic deformation to adhere to a substrate. 

Because they are inert gases, nitrogen and helium are the two most common gasses used to accelerate the powdered metal in this process. The effect is similar to a pneumatic cannon, shooting metal particles at supersonic speeds. Due to the sharp edges of the angular powder and high speed at which it is traveling, the powder is simply embedded into the surface of the substrate. This method is also sometimes referred to as ballistic adhesion. Cold spray is more commonly used to coat a substrate than to print a part. 

Directed Energy Deposition Method 

This method is more complex than the others we have discussed. Directed energy deposition (DED) utilizes thermal energy to fuse materials together while the materials are being deposited. The fusing can be performed using a laser, electron beam, or plasma arc. The material can be in the form of metal powder or wire. The powders used in a DED system are typically of larger sizes than those used in LPBF. DED can be used to build full parts but is more commonly used for part repair or adding layers of material to an existing substrate. 

The Different Types Of Powdered Tantalum 

Although most powdered metals can be used for these processes, in this article, we will focus on tantalum because of its importance to this industry. At Global Advanced Metals (GAM) our additive manufacturing powders have high purity, excellent flow, and particle size distributions that work with all major printing technologies. 

Angular powders can best be described as jagged, solid particles, much like shards of broken glass. The sharp points and edges make it easier for the particles to be mechanically embedded in the target surface. The angular powders produced by GAM have good flow properties and high purity. On the other hand, spherical powders are composed of near perfectly round, uniform particles yielding excellent flow properties. Not only do spherical powders have a more consistent size, but they also have a consistent shape that can be melted together easily. The spherical tantalum powders produced by GAM have flow properties better than angular powders. This difference is why spherical powders are more predominantly used in 3-D printing with metal powder technologies.  

Industries That Benefit From Additive Manufacturing 

Virtually any industry can benefit from additive manufacturing; however, some fields have seen more benefits than others. For instance, additive manufacturing has proven to be extremely useful for manufacturing highly complex parts. Medical implants, especially smaller devices that require complex geometries, are much easier to produce in this way. Tantalum is a key component for such devices. 

Because it minimizes waste, additive manufacturing is a great option for those working with scarce or expensive materials such as tantalum. While it is possible to melt and re-use the leftover metal from subtractive manufacturing, this adds extra steps and expense and still won’t reach the same level of efficiency. 

Additive manufacturing is very popular in the aerospace and automotive industries for similar reasons as in the electronics industry. This process also allows parts and products to be made with less excess weight, a significant advantage in the aerospace industry. These industries have also been known to use additive manufacturing for the quick and easy preparation of prototypes. 

The medical field is another industry that has embraced additive manufacturing because of its many advantages. The design of a medical implant, for instance, requires a lot of testing before it can be deemed safe and ready to use. Additive manufacturing makes it far easier to build and test those initial prototypes. In addition, many medical devices, from implants to prosthetics, make use of a complex mix of materials. Additive manufacturing makes it far easier to build items from a complex material matrix. 

The applications for additive manufacturing are far-reaching and growing every day. At GAM, we are proud to be able to help our customers achieve their goals using the most innovative technology and highest-quality materials.