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Subtractive Vs Additive Manufacturing
By 3D Printing Store
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Subtractive Vs Additive Manufacturing

Additive vs. Subtractive Manufacturing

 

Additive manufacturing processes build objects by adding material layer by layer, while subtractive manufacturing removes material to create parts. Though these approaches are fundamentally different, subtractive and additive manufacturing processes are often used side by side due to their overlapping range of applications.

It can initially be difficult to understand how to make the most of each type of technology to optimize product development and manufacturing. Both have cases where it makes sense to use one approach over the other, for example, one process can be more useful for a certain production volume, or at a specific stage of product development.

 

Process

Materials

Stereolithography (SLA)

Varieties of resin (thermoset plastics), high-strength, rigid, flexible, elastic, heat-resistant, castable (wax-like)

Selective laser sintering (SLS)

Engineering thermoplastics, such as nylon

Fused deposition modeling (FDM)

Standard thermoplastics, such as ABS, PLA, and their various blends

Material jetting

Varieties of resin (thermosetting plastics)

Binder jetting

Gypsum (full color), metals

Selective laser melting (SLM) or direct metal laser sintering (DMLS)

Soft and hard metals

Electron beam melting (EBM)

Electron beam melting (EBM)



Subtractive manufacturing is an umbrella term for various controlled machining and material removal processes that start with solid blocks, bars, rods of plastic, metal, or other materials that are shaped by removing material through cutting, boring, drilling, and grinding.

These processes are either performed manually or more commonly, driven by computer numerical control (CNC).

In CNC, a virtual model designed in CAD software serves as input for the fabrication tool. Software simulation is combined with user input to generate toolpaths that guide the cutting tool through the part geometry. These instructions tell the machine how to make necessary cuts, channels, holes, and any other features that require material removal, taking into account speed of the cutting tool and feed rate of the material. CNC tools manufacture parts based on this computer-aided manufacturing (CAM) data, with little or no human assistance or interaction.

 

Process

Material

CNC machining (turning, drilling, boring, milling, reaming)

Hard thermoplastics, thermoset plastics, soft metals, hard metals (industrial machines)

Electrical discharge machining (EDM)

Hard metals

Laser cutting

Thermoplastics, wood, acrylic, fabrics, metals (industrial machines)

Water jet cutting

Plastics, hard and soft metals, stone, glass, composites



When to Use Subtractive and Additive Manufacturing

While there are key differences, subtractive and additive manufacturing are not mutually exclusive. In fact, they are quite often used side by side and at different stages of product development and in manufacturing.

The prototyping process, for example, often relies on both additive and subtractive tools. Early concept models and prototypes are generally more economical and faster to produce with plastic additive manufacturing processes, such as stereolithography (SLA) or selective laser sintering (SLS). 3D printing offers a wide variety of material options for the functional prototyping of plastic parts. Additive technologies are also typically better suited for small parts and highly complex or intricate designs.

When later stages of the development process require larger batches, subtractive processes become more competitive. Larger, less complex objects also lend themselves more to subtractive manufacturing. Due to the myriad choices in surface finishes and the speed of the process, subtractive manufacturing is most often the choice for fabricating finished parts. As metal 3D printed parts can be cost-prohibitive, subtractive processes are a better choice for metals parts for all but the most complex designs.

In manufacturing, subtractive and additive processes often complement each other in the production of tooling, jigs, fixtures, brackets, molds, and patterns. Manufacturers often use plastic 3D printed parts for fast, custom, low-volume, or replacement parts and opt for subtractive metal processes for higher volumes or parts that are subject to more extreme mechanical stress and strain.

Utilizing both additive and subtractive manufacturing results in a hybrid process. This allows product designers and manufacturers to combine the versatility and quick turnaround times of additive manufacturing with the strength of subtractively produced parts.



10 months ago
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