3D Printing vs. CNC Machining: Understand the Differences

The world of manufacturing now has different methods for machining different elements. While CNC machining has been known for decades now, 3D machining has also recently started making some impacts in the manufacturing market. 3D printing uses the method of additive manufacturing in contrast to the subtractive manufacturing methods of CNC machines. Both of these technologies have revolutionized the production, prototyping, and design of various products. But there are several fundamental differences between 3D printing vs CNC machining, and in this blog, we are going to discuss them in detail. 

Difference Between CNC Machining vs 3D Printing: 

Here are some of the major differences between the methods of machining of 3D printer vs CNC machine: 

1. Fundamental Method Difference:

The first and foremost difference between the two methods of machining is their method of operation. 

3D Printing: 3D printing is an additive manufacturing process. It helps in the creation of a product by depositing materials layer by layer, following a digital 3D model. The printer builds the product from the bottom up using different materials like plastics, metals, and resins. Different technologies like Fused Deposition Modeling (FDM) and Selective Laser Sintering (SLS) are used for 3D printing. 

CNC Machining: CNC machining is a subtractive manufacturing process. It starts with a workpiece of materials like metals, composites, and plastics, and then the cutting tool cuts the workpiece as per computer generated instructions to give the required shape. Key processes of CNC machining are milling, drilling, and grinding. 

2. Accuracy and precision: 

3. Material Compatibility: 

Here is the material compatibility of 3D printing vs CNC machine manufacturing: 

3D Printing: Plastics like PLA, ABS, Nylon, TPU. Metals like stainless steel, titanium, and aluminum. Different composites like carbon fibre filled and glass filled filaments. 

CNC Machining: CNC machines are also compatible with different elements like metals like brass, aluminum, copper, steel, both mild and stainless, and titanium. Different plastics like ABS, PEEK, polycarbonate, and Delrin are also machined using CNC machines. 

4. Geometric Flexibility: 

Let’s find out which type of machining has better geometric flexibility in CNC machining vs 3D printing: 

3D Printing: 3D printing can be regarded as a kind of complex machining. One of the major benefits of 3D printing is that it can create complex and intricate shapes that are hard for CNC machines to produce, as designing here is not limited to the capabilities of the machine. But they also often require printing support structures for overhanging features. 

CNC Machining: CNC machines have high repeatability, which is excellent for creating parts batch after batch. CNC machines are also very capable of machining internal features of different products. But one of their problems is low tool access; deep cavities are tough for machines with limited tool capabilities. For a more geometrically capable CNC machine, check out the used multi axis CNC machines of MachineStation.

5. Speed and Production Time: 

Here is the difference between 3D printing vs CNC machining regarding speed and production time:

3D printing: 3D printing is ideal for one off production and prototyping works. The rapid prototyping feature of the 3D printers enables the designers to iterate quickly and test multiple versions of the same product in just a day rather than a week. For large batches and high volume productions, 3D printing is generally a slower and less cost effective option compared to CNC machines.

CNC machining: CNC machining is obviously a better option for large batches and high volume production of identical parts. Setup may take some time, but once it is done, production can be done at a rapid speed.

6. Strength and Durability: 

The next factor in the difference of 3D printing vs CNC machining that we need to know is the difference in strength and durability: 

3D Printing: The 3D printer products have anisotropic strength (weaker along layer lines). The 3D printing methods are great for visual models and light duty parts. Metal 3D prints can be strong but they are also very costly. 

CNC Machining: CNC machined parts are cut from solid stocks, so they can retain the full material strength. The CNC machined parts are ideal for high demand industries like aerospace, automotive, defense, and medical. 

Advantages and Disadvantages of 3D Printing: 

Here are the major benefits of 3D printing in the debate of CNC machining vs 3D printing: 

• You get more machining freedom as you can make different complex geometric parts with the help of 3D printing. 
• Rapid prototyping can be done because the setup time is low, which accelerates the production development cycle. 
• The amount of waste generated is minimal, which further helps in sustainable manufacturing.
• It is easier to create customized products, such as medical implants, using 3D printers without requiring expensive tooling changes. 

Here are the drawbacks of 3D printing that you need to consider:

• The method of 3D printing, which builds layer by layer, is actually a slower process for large scale production. 
• The surface finishing for 3D printing is not top notch, so additional post production processes, such as sanding or coating, are often required for smoothness. 

Advantages and Disadvantages of CNC Machining: 

Here are the major advantages of CNC machining in the debate of 3D printing vs CNC machining: 

• CNC machining can bring much more accuracy and tighter tolerances for repeatable manufacturing work. 
• CNC machining provides excellent surface finish with minimal requirement of post processing. 
• CNC machines have the capability of machining a wide range of materials, which includes hard materials like titanium. 
• Scalability is also one of the major benefits of CNC machines in the debate of 3D printer vs CNC machine, as it can produce different products with repeatable tolerance. 

Here are the drawbacks of CNC machining that you need to know for the debate of 3D printing vs CNC machine manufacturing: 

• CNC machining produces high material waste, which becomes a big hurdle for shops focusing on sustainable manufacturing. 
• The setup time of CNC machines is high, which makes it not so ideal choice for prototyping work compared to 3D printers. 

Which One to Choose? 

Here are the times when you should choose 3D printing over CNC machining: 

• For rapid prototyping.
• For complex parts machining.
• For low volume productions. 
• For sustainable manufacturing. 

Here are the times when you should choose CNC machining over 3D printing: 

• For high precision manufacturing works. 
• For durable machining works. 
• For medium to high volume production works. 
• When a superior surface finish is needed. 

Conclusion: 

3D printing vs CNC machining is a debate that cannot be answered in one line because they have their own pros and cons. So, before choosing which one you should go with, you should understand what your machining needs are and then make the final decision. If you decide to go with CNC machining, then go and check the used CNC machine collection of MachineStation. 

FAQs: 

1. Will 3D printing replace CNC machining?

Ans: 3D printing is unlikely to replace CNC machining because they are not interchangeable methods, and their machining processes are totally different. 

2. Is CNC machining faster than 3D printing?

Ans: For smaller parts, 3D printing might be a faster option, but CNC machining is faster when it comes to large volume production. 

3. Which is more accurate, CNC machining or 3D printing?

Ans: CNC machining offers higher accuracy and tighter tolerances (as precise as ±0.005 mm), making it ideal for precision parts.