Additive Manufacturing vs Subtractive Manufacturing

Manufacturing processes can often be classified as either additive or subtractive. In both types of processes, companies build objects from materials. Materials can include plastics, thermoplastics, iron, steel, carbon and more. While both additive and subtractive manufacturing processes are used to build objects from materials, though, they aren’t the same. So, what’s the difference between additive manufacturing and subtractive manufacturing?

What Is Additive Manufacturing?

Additive manufacturing encompasses processes that involve building objects through the addition of materials. When a company builds an object by adding materials to it, it’s considered additive manufacturing. The materials are gradually added to a bed or substrate, allowing for the production of a new object in a different size and shape than that of the raw materials.

Most additive manufacturing processes involve 3D printing. The term “additive manufacturing,” in fact, has become synonymous with 3D printing. 3D printers are machines that deposit material onto a print bed. Therefore, they build objects through the addition of materials. A typical 3D printer works by releasing extruded material out of a nozzle. It builds the base layer, after which it builds the next-highest level. The 3D printer will continue to build each individual layer until the object is completed.

What Is Subtractive Manufacturing?

Subtractive manufacturing, on the other hand, encompasses processes that involve building objects through the removal of materials. It’s essentially the opposite of additive manufacturing. Rather than adding materials, companies perform subtractive manufacturing by removing materials. It often begins with a large piece of raw material. Companies then remove excess material from it so that it creates a new object in a smaller size and a different shape.

Turning and milling, for example, are considered subtractive manufacturing processes. Turning is a form of cutting that specifically uses a rotary cutting tool to remove material from a workpiece. In comparison, milling uses a stationary cutting tool to remove material from a rotating workpiece. Since they both remove material from workpieces, turning and milling are considered subtractive manufacturing processes.

Why Additive Manufacturing Is on the Rise

While subtractive manufacturing isn’t expected to fade anytime soon, additive manufacturing has become increasingly popular among manufacturing companies. With additive manufacturing, companies can build objects while producing little or no waste. Subtractive manufacturing is more wasteful because it removes material from workpieces.

Additive manufacturing is also a better choice for building objects in complex shapes. If a company is building an object in a complex shape, subtractive manufacturing processes may not work. Using a 3D printer — or another additive manufacturing machine — companies can overcome this challenge.

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