How Does Additive Manufacturing (AM) Differ from Traditional Manufacturing?

November 17, 2021

Metal additive manufacturing can be a complicated topic, especially for those that are new to the industry. But metal AM is just one way to manufacture a part; there are dozens of other “traditional” methods that have been relied upon for centuries. While metal AM is a relative newcomer, it presents a world of opportunity for countless industries looking to print parts with complex geometries and assert more control over their supply chains without relying on complex networks of skilled machinists.

In part one of this introductory guide to metal AM, we discussed additive manufacturing from a high level, highlighting the steps from design to post-processing needed to create a finished part. In this second installment, we’ll look at some traditional forms of manufacturing, and discuss how metal AM differs—and what makes it unique.

Casting and Forging

Casting is one of the oldest known forms of metallurgy, with roots in ancient Mesopotamia. There are multiple forms of casting: die casting, plaster casting, sand casting, and more, but the process is fundamentally similar for all of them: molten metal is poured into a mold where it cools and hardens. The part is then extracted and post-processed, which leaves the finished part for its final use.

There are several benefits of casting: the process can be less expensive because it relies on lower-tech machinery, parts are sturdy with high compressive strength and can be made from a multitude of materials, the process can be used to produce large objects, and more. As automation and higher-tech design software has transformed many facets of the manufacturing field, castings can handle more complex designs compared to decades ago.

For all of its positive attributes, however, casting also has weaknesses. The process doesn’t enable precision parts, particularly when it comes to complex internal structures. Additionally, there are long lead times for parts because they require specialized design engineers and machinists; and each new design iteration requires separate casts to be made, which makes the process especially long for developing new parts.

Brazing and Welding

Like casting and forging, brazing and welding are two of the most established forms of parts manufacturing. And much like casting, there are many forms of brazing and welding with an overarching process that unifies them: metal with a lower melting point is heated to its liquid state and used to bond two or more harder pieces of metal together. Brazing differs from welding in that it’s an automated process; parts can be mass-produced in a furnace by heating the filler metal and flowing it through joints to bond metals. Welding can be automated using robotics, but that process tends to be much more costly, and is typically done manually by skilled welders.

Brazing and welding both have their advantages. For brazing, because of its reliance on automation, it’s often chosen for mass-produced parts. Welding, especially when done by a skilled welder, is often chosen for its ability to create complex and small parts that are unreliable to mass produce. Both processes are also chosen because multiple materials can be fused together using filler metals.

Brazing, much like casting, can be unreliable when producing complex part geometries, however, and with welding’s reliance on skilled craftspeople (in an industry that is experiencing a labor shortage), turnaround times on parts can be unrealistic for companies who need specialty parts quickly and can’t afford months of lag time.

CNC Machining

Computer Numerical Control (CNC) machining uses pre-programmed computer software to operate factory machines such as lathes, mills and grinders to manufacture a part. CNC machining is a subtractive process, meaning it starts with larger pieces of metal that are manipulated within the CNC process to create the finished part.

CNC machining is prized for its precision; since the entire process is automated and controlled by complex computer programs and specially calibrated machines, the resulting parts tend to be high-quality, with exact angles and uniformity. The reliability of the process and relatively low labor involvement also makes it ideal for the mass production of precision parts.

With the precision capabilities of CNC machining, however, comes higher costs. Even though the process doesn’t require significant specialized labor involvement, CNC machines are expensive. The price of parts can also go up based on complexity. Producing parts with lower angles or thin walls can be a challenge for CNC machining, and as the level of difficulty increases so does price and part reliability.

Where Additive Manufacturing Excels

Ostensibly, advanced metal additive manufacturing takes many of the strengths of welding and CNC machining and reinvents it into something new and different. Unlike CNC machining, metal AM is an additive process rather than subtractive. Laser powder bed fusion (LPBF), which Velo3D uses, begins with powdered metal that is heated to its melting point using precisely calibrated lasers (like welding), which bonds each layer to the layer beneath it. Layer by layer, the part is built from the ground up, working off precise specifications programmed into advanced software (like CNC machining).

Because advanced metal AM is automated, it creates precision parts without the variance of even skilled processes like casting, forging, brazing, and welding. Velo3D has also pioneered a SupportFree™ printing process, which enables Velo3D’s end-to-end solution to produce parts with complex internal structures, thin walls, and low angles with little to no support structures. This in turn reduces the need for complicated post-processing endemic to conventional manufacturing processes.

Another game-changer with Velo3D is the integration of software and hardware. Since Velo3D design files are unique to Velo3D machines, any part can be printed on any machine, which offers a level of control that is impossible with other manufacturing processes. This integration helps companies to produce parts on demand, which solves many of the complications that plague traditional manufacturing processes within the supply chain. The resulting lead times for parts manufactured through Velo3D’s end-to-end process are weeks rather than months.

Though the capabilities of advanced metal AM enable complex parts in a fraction of the time, there are some considerations to understand when determining which manufacturing process is right for you.

For example, mass production of less complex parts is still better left to more generalized processes like CNC machining. Still, for industries across the spectrum with a desire to innovate and that need consistent, high-quality, specialized parts without months of lead time, Velo3D’s end-to-end advanced metal AM solution is an ideal fit.

In part three of this series, we’ll look more in depth at the ins and outs of the advanced metal AM printing process.

If you’re interested in learning more about the Velo3D metal AM process, contact one of our expert engineers today.

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About the Author

Amir Iliaifar

Director of Content

Amir Iliaifar is the Director of Content at Velo3D where he oversees the production and distribution of Velo3D’s global digital content marketing initiatives. Prior to joining the company, Amir worked for a leading professional drone manufacturer, several SaaS companies, and as an automotive tech journalist. He holds a Master of Arts in Digital Communication from the University of North Carolina at Chapel Hill.