Additive vs. Subtractive Manufacturing: Which approach is best?

Metal 3D Printing in Boston

Object printed on metal 3d printer. A model created in a laser sintering machine close-up. DMLS, SLM, SLS technology. Concept of 4.0 industrial revolution. Progressive modern additive technology.

Manufacturing firms across the country continue to pursue operational optimization strategies in an effort to simultaneously reduce costs and generate products primed for success. A significant number are revisiting their core production workflows. Some are intent on improving existing processes while others embrace newer approaches.

Two camps have materialized due to this sector-wide search for operational improvement. Members of the first group, most of whom can be categorized as traditionalists, support subtractive manufacturing, which centers on a technique called controlled material removal. Those in the second group, the reformists, tout new-age additive methods wherein automated assets create three-dimensional objects using precision tools and smaller amounts of raw material.

Both approaches come with unique benefits and drawbacks. Companies interested in collaborating with third-party product developers and manufacturing firms should examine additive and subtractive strategies to determine which methodology makes sense in the context of their respective business goals.

Understanding subtractive manufacturing
The computer numerical control machine embodies the subtractive manufacturing methodology. This device can leverage any number of tools, including drills and saws, to wick away at large amounts of raw material and create prototypes or finished products at scale. While CNC machines have some manufacturing limitations, these fixtures and the subtractive workflows they power are applied broadly across numerous industries. However, while subtractive manufacturing can certainly generate quality products at an accelerated pace, it also 
creates considerable waste, according to PricewaterhouseCoopers.

Manufacturing firms that use subtractive methods must start with bulk raw material. As CNC machines whittle away at this matter, unusable remnants, called scrap, fall to the shop floor. PwC analysts used data from the U.S. Geological Survey to determine that American manufacturers waste almost one-quarter of the raw materials they purchase, an unfortunate outcome linked directly to subtractive methods. This waste inflates the cost of production, leading to higher-than-necessary price quotes. That said, organizations looking to outsource the mass production of durable products - especially items with metal components, according to - would be wise to consider partners with subtractive manufacturing workflows. Even with the slightly higher costs, enterprises can be sure that the final products are sound and ready for distribution at scale.

Understanding additive manufacturing
The additive manufacturing methodology, like the subtractive approach, is inextricably linked to a specific piece of equipment - in this case, the 3D printer. As stated above, additive workflows are designed to create items from scratch using carefully managed amounts of raw material. For instance, the 3D printer GE uses to craft airplane parts leverages expertly programmed lasers to carve away at small 
beds of cobalt-chromium powder, the MIT Technology Review reported. The device creates complicated metal goods that would require multiple fabrication processes if produced via subtractive methods. This cuts production time considerably. And, of course, the printer drastically reduces waste. Together, these variables could result in production cost savings as high as 90 percent, according to analysts for the U.S. Department of Energy. For this reason, an estimated two-thirds of American manufacturers have adopted additive processes, PwC found.

That said, this methodology does come with some drawbacks. First of all, industrial 3D printing technology is expensive. Additionally, these devices cannot fabricate product at scale and require adopters to invest in additional employee training as such systems require different skills than a CNC machine. On top of this, many in the manufacturing space have expressed concern over end product quality. That said, additive manufacturing technology is advancing quickly. In fact, 56 percent of firms believe 3D printers will dominate the manufacturing space within the next three-to-five years, PwC reported.

Today, these tools facilitate accelerated prototyping and are immensely valuable during the opening stages of the product design process.

Subtractive and additive workflows have their places within today's manufacturing environment. Businesses must consider how both methodologies might meet their production needs. Here at Datum3D, we leverage both strategies, allowing businesses of all sizes to design and fabricate prototypes at an accelerated pace, while also crafting products that are ready for production at scale.    

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