Compared to subtractive manufacturing technologies such as CNC machining and metal casting, 3D printing offers reduced production costs and short lead times. But how does the process work?
Regardless of the specific solution, all 3D printing processes for metal build on top of a bed of granular powders. These powders can range from rough spherical particles required by DMLS to finer graded materials used in binder jetting.
What is 3D Metal Printing?
The term 3D metal printing refers to the process of creating a solid, three-dimensional metal object using an additive manufacturing method. Unlike traditional machining or casting, which requires the creation of physical moulds, the 3D printing process uses digital design files to build the metal object layer by layer until it is complete. The finished result is a fully-dense, precision-made metal component that is as strong as a forged part but lighter in weight and cheaper than machining.
The main metal 3D printing technology is known as Direct Metal Laser Melting (DMLS). This is an additive powder bed fusion process that works by using a high-powered laser to sinter alloy powder particles into a layer of a finished metal component. Once one layer is complete, the laser moves to the next section of the build and repeats this process. This is a very versatile and efficient process, and DMLS parts are used across many different industries.
A relatively newcomer to the metal 3D printing world is Bound Powder Extrusion (BPE). This process is similar to DMLS and SLM but uses bound metal powders which are evenly dispersed within waxy polymers. This allows for a much greater range of materials to be printed with, including some exotic alloys such as titanium and cobalt.
Once a print has been completed, the finished metal part will often require post-processing treatments. Depending on the printing technology, this might involve heat treatment to improve mechanical properties, sand blasting to remove any remaining support structures and/or coating/polishing for aesthetic quality. These steps can be lengthy and expensive, but are vital to ensure the end result is a fully functional and finished metal part.
It is also worth noting that a number of the processes involved in the printing of a metal component require the use of costly powdered metals, which adds to overall costs. This is an area where the market is rapidly changing, and more affordable solutions are starting to become available.
Unlike other forms of printing, which use liquid or solid materials, 3D metal printers are made by using a layering process. A laser or other energy source is focused on a bed of fine steel powder to melt and fuse it together. This builds up a layer at a time until the component is complete. The printed component can then be used as it is, or it can be machined and finished for additional function. This is a far faster and less wasteful process than traditional metal cutting, which can involve carving into roughly shaped chunks of metal that have to be welded or otherwise joined.
The most common method for printing metal components is called Selective Laser Melting (SLM) or Direct Metal Laser Sintering (DMLS). This 3D printing technology uses a laser to sinter or bond metallic alloy powder particles together into layers and then builds up a solid object layer by layer. It is used for a wide range of applications, from making complex metal prototypes to producing final parts and assemblies. It can produce intricate shapes that would be very difficult to make with other manufacturing methods, including internal lattice structures and conformal cooling channels.
The rapid temperature changes that occur during the 3D printing process can also cause warping in the printed component. To minimize this, a technique called randomized scanning is used, which ensures that areas of the part are scanned with equal intensity and prevents a single area from receiving more heat than another. It's not the only way to minimize warping, however, and researchers are continually working to optimize 3D printing for metal to achieve stronger, lighter parts.
When it comes to 3D printing, metal is one of the fastest-growing segments, and with good reason. Its high strength, resistance to abrasion and corrosion and electrical conductivity make it an attractive material for a wide range of industrial applications. But controlling the many variables that impact part quality, from design to build preparation and post-processing, remains challenging.
The primary process used for metal 3D printing is direct metal laser melting (DMLM). This technique uses a powerful laser to melt and fuse successive layers of powdered metal into three-dimensional, fully dense parts. This technology produces parts with a minimum of wasted material and precise internal features that cannot be produced with traditional manufacturing techniques.
While this approach is more restrictive than other methods, it allows users to create complex, lightweight metal components with a wide variety of alloys. It also reduces the need for support structures, which can help keep part costs down and improve strength.
Almost every metal printed part requires some form of post-processing, which removes excess material and adds finishing details to the surface. These additional steps may include machining, electroplating, sanding, and grinding. At Star Rapid, we offer a full complement of finishing services to deliver the final product you want.
The Final Product
When it comes to 3D metal printing, the finished result looks incredibly impressive. The prints are beautiful, shiny and durable, with a unique finish that can appear modern, industrial or rustic. They also look extremely high-definition, which adds to the unique feel and makes them stand out from other printed materials.
There are several different types of 3D printers that can print with metal, including Selective Laser Melting (SLM), Electron Beam Melting (EBM), Direct Energy Deposition (DED), Binder Jetting and Bound Powder Extrusion. Despite some differences, these processes all belong to the powder bed fusion 3D printing family, which is where they share similar properties.
This is because they all use a laser to scan and selectively melt (or sinter) the metal powder particles, building a part layer by layer. They are able to produce complex geometries and parts with conformal cooling channels, which are impossible to make through traditional subtractive or casting technologies.
Despite this, the cost of printing in metal can still be prohibitive for some applications. This is because the machines themselves can account for a substantial proportion of overall costs, along with labour, materials and preparation. However, there are new developments in metal printing that aim to bring down these costs and increase the speed at which parts can be produced.
This type of printing is becoming more popular as it can be used for a wider range of applications, such as prosthetics and implants. It can also be used to make custom tools, and there are even projects in the works that are exploring organic printing and bio-printing. As the technology continues to evolve, there are plenty of exciting opportunities for it in the future.