Additive Manufacturing (AM) and CNC (Computer Numerical Control) manufacturing are two dominant prototyping methods. Understanding the differences between these methods is crucial for businesses and designers looking to improve their new product development processes.
This article explores the differences between AM and CNC manufacturing, explaining their unique abilities and applications. By understanding this comparison, readers will learn about the strengths of each method and how to make smart choices when picking the best manufacturing method for their specific prototyping needs.
What Is CNC Manufacturing?
CNC manufacturing, which stands for Computer Numerical Control manufacturing, uses G-code pre-programmed computer software to dictate the movement of the tools. This technology is commonly used in manufacturing to control complex machinery, including mills, turners, lathes, grinders, and routers.
CNC manufacturing allows for precise and efficient production of components, parts, and products by automating the operation of machinery through computer-aided design (CAD) and computer-aided manufacturing (CAM) programs. The automation of CNC enables high levels of precision, repeatability, and cost efficiency.
What Is Additive Manufacturing?
Additive manufacturing, familiarly known as 3D printing, is a process of creating three-dimensional objects by adding material layer by layer. This manufacturing technique produces complex geometries and intricate designs that may be difficult or impossible to achieve using traditional manufacturing methods.
Additive manufacturing encompasses various technologies such as stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), and others, each with its unique approach to building objects layer by layer using materials such as plastics, metals, and ceramics.
Additive manufacturing has applications in industries ranging from aerospace and automotive to healthcare and consumer goods, offering advantages such as design flexibility, rapid prototyping, and customization.
Major Differences Between Additive Manufacturing and CNC Manufacturing
Though additive manufacturing and CNC machining enjoy wide application in rapid prototyping, they differ significantly in material usage, design flexibility, lead time, production volume, cost, and surface treatment.
Material Usage
AM: Adds material layer by layer, resulting in minimal waste and the ability to create complex internal geometries.
AM can use many materials, including plastics (such as ABS, PLA, and nylon), metals (such as stainless steel, aluminum, and titanium), ceramics, composites, biomaterials, glass, paper, wax, and even food products for specialized applications.
CNC: Removes material from a solid block or billet, often leading to more waste material, especially for intricate designs.
CNC machining uses fewer types of materials than 3D printing. In prototyping, the most commonly used materials are ABS, PC, PMMA, PA, stainless steel, aluminum, brass, copper, etc.
Design Flexibility
AM: Offers high design flexibility, enabling the production of complex and customized shapes with relatively little additional cost.
CNC: Provides precise and accurate machining of solid raw materials but may have limitations in creating intricate internal structures.
Lead Time
AM: Generally faster than CNC manufacturing. However, it is slower for large-sized and more intricate parts due to the layer-by-layer building process.
CNC: Typically slower for one-off parts. However, CNC is faster for larger volumes, as it involves the removal of material from a solid block in a more continuous and repeatable process.
Production Volume
AM: Well-suited for low to medium production volumes, especially when customization and complexity are required. It is particularly advantageous for producing small to medium quantities of highly complex parts.
CNC: Ideally suited for medium to high production volumes, where scalability helps reduce per-unit costs. CNC manufacturing makes larger quantities of parts with relatively less complexity.
CNC machining is a better choice than 3D printing for one-off prototypes that require high precision.
It is also suitable for creating complex plastic parts by splitting one part into several pieces and then gluing them together. You can also save money by doing so.
Cost Considerations
AM: Initial setup costs for additive manufacturing can be relatively low. And, for low to medium production volumes, the price per unit may be competitive due to reduced tooling and setup expenses.
CNC: CNC manufacturing generally involves higher initial setup costs than AM due to the high cost of CNC machines. For low production volumes or highly complex parts, the unit cost may be higher due to longer machining times, material waste, and tooling expenses.
Surface Finish and Post-Processing
AM: Additive manufacturing processes can result in a layered surface finish, which may require additional post-processing to achieve the desired smoothness and surface quality.
Depending on the specific AM technology used, the surface finish may vary, and additional finishing processes such as sanding, polishing, or chemical treatments may be necessary to achieve the desired appearance and texture.
CNC: CNC manufacturing typically produces parts with precise and smooth surface finishes, especially when using high-quality cutting tools and appropriate machining parameters. The surface finish achieved through CNC processes often requires minimal additional finishing, particularly for metals and high-quality plastics.
There may be a need for additional finishing for aesthetic and protective purposes. The common ones are polishing, painting, powder coating, electroplating, anodizing, etc. Different materials apply different surface treatments.
Choosing Between Additive Manufacturing and CNC Manufacturing
Below is a quick checklist for choosing between AM and CNC.
Complexity and Customization
Choose AM for complex, customized designs with intricate geometries.
Choose CNC for precise, high-quality parts with less complexity.
Production Volume and Cost
For low to medium volumes and complex parts, AM may be cost-effective.
For medium to high volumes and simple parts, CNC is often more cost-effective.
Material Options
AM offers a variety of materials, including polymers, metals, and composites.
CNC provides precise machining of metals and hard plastics.
Lead Time and Post-Processing
AM can offer shorter lead times for prototyping and may require post-processing for surface finish.
CNC may have faster lead times for high-volume production and often requires minimal post-processing.
Final words
You can take time to learn about additive manufacturing and CNC manufacturing by studying real examples and trying things out. Welcome to contact experts at X Rapid Technologies to help you decide on the best prototyping methods for your new design.
