WILL ADDITIVE MANUFACTURING (3D PRINTING) ECLIPSE CNC MACHINING?
Issue Time:2016-12-07
3D printing, also known as additive manufacturing, is gaining momentum and certainly has raised eyebrows in the precision machining industry. In fact, some have speculated that it has the potential to replace traditional milling and machining operations in the not so distant future. The process whereby a three dimensional solid object is created from a digital model using an additive process, as opposed to the subtractive methods used by CNC mills for example, has been receiving a lot of buzz. In machine shops, it has revolutionized prototype development and even provided end- end-use parts created out of engineered plastics. Herein lies the limitation however; 3D printers currently lack the speed, efficiency and end-product quality to match the CNC machining tools used in fabricating METAL parts. There are fundamental problems still to overcome, and although the technology exists to print metal parts (SLM & DMLS machines), the gap between printed parts and components that are truly usable is still massive.
Cost is an initial barrier to entry. Selective Laser Melting (SLM) machines, the most commonly used for the 3D printing of metals, and Direct Metal Laser Sintering (DMLS) machines can cost upward of one million dollars. A lot to pay and out of reach for most CNC machine shops, especially given the lengthy part build times, lasting several days to weeks. It takes a lot of time to deposit layers starting from scratch instead of an existing billet of metal. Surface finishes also leave a lot to be desired. Melted metal is deposited layer by layer with additive methods leaving an inherently rougher finish in terms of aesthetics, functionality and accuracy. There are also metallurgical advantages to the molecular structure of billets when compared to their 3D “Layered metal” counterparts such as malleability, ability to be heat treated, strength, etc. Lastly, 3D printing is significantly hampered in its range of quality settings. Because of the time involved and the layered nature of deposition, experimenting and prototyping are made more difficult if not impossible. The ability to create a rough part fast for testing purposes is just not there.

There is also metallurgical advantages to the molecular structure of “Billet” as opposed to its 3D “Layered metal” counterpart.. Such as malleability, ability to be heat treated, strength, etc.

Will metal 3D printing replace CNC machines in the near future? We don’t think so, and ultimately we don’t see big changes in the future of traditional CNC milling and machining processes. CNC machining centers and machine shops are still, and will be, the ideal choice for high-quality and efficiently manufactured parts. Yes, 3D printing is fun, versatile, more user-friendly and has its role in terms of conceptualizing prototypes and difficult design applications, but it has its limitations as we’ve noted. Subtractive methods will be the preferred choice moving forward for the precision machining industry, and additive manufacturing will have its place as a complementary application.
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