CNC Machining vs 3D Printing: Detailed Comparison

If you’re making machined parts and trying to choose between CNC machining and 3D printing, it’s good to know how each process works. In this blog, let’s talk about the comparison between CNC machining vs 3D printing.

What is the Difference Between Subtractive and Additive Manufacturing?

CNC machining is subtractive; you cut the material from a solid block to make a part. It’s been around for a long time and works well for both prototypes and final parts.

3D printing is additive; you build parts layer by layer using plastic, metal, or rubber-like material. It’s newer and was mainly used for quick manufacturing of custom parts and prototypes, but now it’s also good for small to medium production, especially if the part is complex.

Keep reading further to get more details about the difference between CNC and 3D printing.

¿Qué es el mecanizado CNC?

Mecanizado CNC is short for Computer Numerical Control machining. As mentioned above, it is a way to make parts by cutting material away from a solid block. A computer controls the tools, so you get very accurate and detailed parts. You can use it to make one part, like a prototype, or a lot of the same parts for mass production.

This method started back in the 1950s at MIT and changed how people make things because it made the process faster and more exact.

The process starts with designing your part using CAD software. Then, you turn that design into instructions using CAM software. These instructions, called G-code, tell the machine what to do. The CNC machine reads the G-code and uses sharp tools to cut the part from a solid block. It moves in different directions to make detailed shapes, and motors help it cut very accurately.

Common CNC Machines and Their Functions

Below, we discuss the most common ones and how they work.

CNC Mills: These machines use spinning tools to cut and shape materials like metal or plastic. If you need to make detailed parts with complex shapes, this is the machine for you. It’s often used when you need high precision.

CNC Lathes: Lathes spin the material while a tool shapes it. They’re great for making round items like bolts or shafts. You’ll find them used a lot in car and airplane parts.

CNC Drills: These machines are used to make holes with exact sizes and positions. They’re often used along with other machines when you’re making parts that need perfect holes.

CNC Grinders: Grinders use rough wheels to smooth out metal surfaces. If you’re working on parts that need a shiny or smooth finish, like tools or car parts, this is what you’ll use.

Plasma and Laser Cutters: Plasma cutters use hot gas to slice through metal. Laser cutters use focused light to make clean, detailed cuts. Both are great for cutting sheet metal and creating designs without wasting much material.

Aside from these types, we can also categorize CNC machines by how they move in different directions, as they give different levels of detail. Here’s how the axis system works:

3-Axis Machines: These move up/down, left/right, and forward/back. Perfect for simple shapes and flat surfaces.

4-Axis Machines: These add a rotation to one of the directions. This helps you work on parts with more complex shapes, like curves or angled holes.

5-Axis Machines: These can move in five directions. They give you the most control and are used when you need super-detailed, high-precision parts.

¿Qué es la impresión 3D?

Impresión 3D started in the 1980s as a way to make objects by adding material layer by layer. You can create shapes that are hard to make with regular tools. Over the years, it has developed a lot and keeps getting better.

In the present time, it starts with a 3D model, usually made in CAD software or scanned from a real object. Then, a program checks for errors in the design. Next, a slicer breaks the model into thin layers and creates a G-code file. This file tells the printer how to build the object layer by layer.

Unlike CNC machines that cut material away, 3D printing only adds what’s needed. This means less waste.

Common Types of 3D Printing Technologies

The way material is added depends on the type of 3D printer you’re using. Here’s how it works for the main types:

FDM: You feed in plastic filament. The printer heats it up and lays it down in layers.

SLA: You use liquid resin. A UV light hardens it layer by layer.

SLS: You start with powder. A laser melts the powder to build the shape.

Key Factors When Choosing Between CNC Machining and 3D Printing

When you’re deciding between CNC machining and 3D printing, think about what you really need. Do you need something custom? Do you need it fast? How much can you spend? Does it need to be super accurate?

Both methods are good, but one might fit your project better than the other.

Geometry and Size of Parts

Let’s tackle what’s the best way to manufacture complex parts. If your part has a complicated shape or tiny details, use 3D printing. If your part is simple and needs to be very exact, use CNC machining.

When it comes to part size with CNC, the smallest detail you can cut depends on the tool size. With 3D printing, the smallest shape you can print depends on the nozzle size. Most 3D printers can only make features as small as 1 to 3.2 mm.

File Types

CNC machining uses CAD files, usually in 2D, that are ready to be cut or shaped by the machine. 3D printing uses digital files like STL or OBJ; these files are easy to modify if you need to make quick design changes.

Turnaround Time

CNC machining might take longer because it requires more setup time. 3D printing is faster, especially for one-off parts, prototypes, and small runs.

Design Flexibility

CNC machining works well for making a large batch of identical parts, but if you want customization, do 3D printing. In 3D printing, you can easily change the design for each part.

Repeatability

CNC machining is great for repeating the same part over and over with high precision. 3D printing can repeat designs, but the quality might vary depending on the printer and material you use.

Speed and Product Volume

CNC machining is faster if you need to produce a lot of parts at once. It’s ideal for medium or high-volume production.

3D printing is better for small runs or prototypes. It’s slower for mass production, but it works well when you only need a few parts.

Material

CNC machining works with many materials, like metals (aluminum, steel, titanium) and plastics (ABS, Nylon, PEEK). It can also handle wood and specialty materials.

3D printing mainly uses plastics like PLA and ABS, but can also handle some metals like aluminum and titanium. Some materials, like superalloys, are hard to print and may not be as strong as those made by CNC.

Coste

Regarding 3D printing vs CNC cost, CNC machining has higher upfront costs because of equipment and skilled labor, but it gets cheaper per part when you make a lot of parts.

3D printing is cheaper to start with since it needs less setup and fewer tools, but the cost per part stays the same, so it’s not as cost-effective for large production.

Calidad

CNC machining makes high-quality, precise parts with smooth surfaces. If you need strong, durable parts, CNC is a better choice.

3D printing can also make good parts, but they might need extra finishing. The strength of these parts may not match what you get from CNC machining.

Quick Comparison of CNC machining vs 3D Printing

Pros and Cons of 3D Printing vs CNC Machining

CNC machining and 3D printing both have their advantages and disadvantages, so one might be better for your project than the other. Here’s a simple comparison:

Ventajas del mecanizado CNC

• Makes parts accurately.
• Works with many materials.
• Produces smooth parts.
• Lower cost for more parts.
• Creates tough parts.
• Repeats the same part every time.
• Handles big parts.
• Parts stay strong.

Disadvantages of CNC Machining

• Creates waste.
• Waste is hard to recycle.
• Costly for small jobs.
• Takes time to set up.
• Requires trained workers.
• Struggles with complex shapes.
• Tools wear out often.
• Uses more energy and creates waste.

Ventajas de la impresión 3D

• Handles complex, intricate designs.
• Creates less material waste.
• Supports quick prototyping.
• Cost-effective for small batches
• Easy to modify designs
• Lower setup costs and simpler operation.
• Allows mass customization.
• Makes internal structures and complex shapes.

Disadvantages of 3D Printing

• Lower precision and surface finish.
• Limited material options.
• Requires extra post-processing.
• Less cost-effective for large batches.
• Weaker material properties in some directions.
• Limited by build size.
• Slower for large-scale production.

Applications and Industries

Here’s how you might use each one in different industries:

Mecanizado CNC

Aeroespacial: turbine blades and structural pieces

Automóvil: engine parts, transmission components, and custom tools

Médico: surgical tools or implants

Industrial Equipment: custom parts like molds or dies

Woodworking: furniture, cabinets, or detailed carvings

Prototyping: strong and accurate models of components

Functional Parts: tough parts that work well under stress

Impresión 3D

Creación rápida de prototipos: print out ideas, check the design, and make changes fast

Medical Devices: custom items like prosthetics, dental tools, and body models

Aeroespacial: lightweight parts like brackets or air ducts

Automóvil: test parts or design car interiors before you start mass production

Architectural and Art: detailed building models or unique art pieces

New Industries: 3D printing in fashion (like accessories), construction (building parts), bioprinting (tissues), or even food

Making Molds: molds for casting

Can You Combine 3D Printing and CNC Machining?

You might ask, will 3D printing replace CNC machining? The answer is no. 3D printing won’t fully replace it.

Instead, use both together. 3D print the shape and details, then use CNC to smooth and size it correctly. This helps when you need detailed and exact parts, like for medical tools or planes.

It can save time and improve quality. So, use both when you can.

Which Process Can Replace 3D Printing and CNC Machining?

If you need many of the same part, try injection molding as an alternative to both 3D printing and CNC machining.

It gives smooth, strong parts, but it’s not great if you need just a few or want to change the design.

You make a mold, fill it with melted plastic, and let it cool into a solid part. The mold costs more at first, but each part is cheap in big batches.

Conclusión

Choosing the right manufacturing method, like CNC machining or 3D printing, depends on what you need for your project, your budget, and how many parts you need to make. CNC machining is good for making precise and durable parts. 3D printing is quick and flexible, great for testing ideas.

DEK helps you get custom parts made faster and easier. Take a look at our CNC machining services. With DEK, you get high-quality CNC-machined parts in just 3-7 days for both prototypes and full production.