3D printing vs. CNC machining metal parts

Choosing the right manufacturing path: 3D printing vs. CNC machining metal parts

CNC machining and 3D printing methods come with theirs own set of advantages and considerations, making the choice a complex but critical one for OEMs striving to meet the demands of precision, speed, and cost-effectiveness. Let’s explore the differences between CNC machining and 3D printing and what factors to consider as you’re deciding which method to employ.

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What is CNC machining?

Long a staple in the production of precision metal parts, Computer Numerical Control (CNC) machining is a subtractive manufacturing process in which a computer-controlled machine tool removes material from a solid block or billet to achieve the desired shape. CNC machining is celebrated for its accuracy, repeatability, and capability to produce intricate geometries.

Advantages of CNC machining

CNC machining has been a popular choice for metal manufacturing for many years, and for good reason: 

  • Unmatched precision. CNC machining is synonymous with precision. The process enables manufacturers to achieve tight tolerances and intricate details, making it ideal for applications where accuracy is non-negotiable. 
  • Material versatility. CNC machining supports a wide range of materials, including metals like aluminum, steel, brass, and titanium. This versatility makes it a go-to choice for industries requiring diverse material options. 
  • Surface finish. The surface finish achieved through CNC machining is often superior, eliminating the need for additional post-processing steps. This is particularly advantageous for parts with aesthetic or functional requirements. 
  • High volume production. CNC machining is well-suited for high-volume production, ensuring efficiency and consistency in manufacturing. 
  • Cost-effective for large quantities. While initial setup costs can be relatively high, CNC machining becomes cost-effective over large production runs due to its efficiency and speed. 

Limitations of CNC machining

There are, however, factors that can eliminate CNC machining from consideration in certain instances: 

  • Material waste. The subtractive nature of CNC machining generates material waste, especially when producing intricate parts with complex geometries.
  • Lead times. CNC machining may have longer lead times, particularly for complex parts, compared to certain 3D printing technologies.
  • Tool changes. Tool changes are necessary for different machining operations, adding to production time and cost. 

3D printing metal parts

3D printing has emerged in recent years as a revolutionary additive manufacturing process, building objects layer-by-layer from digital models. While 3D printing initially gained popularity in prototyping, advancements in technology have positioned it as a viable option for end-use parts in various materials, including metals.

Advantages of 3D metal printing

3D printing has risen to popularity quickly for a number of reasons: 

  • Design freedom. 3D printing offers unparalleled design freedom, enabling the production of complex geometries and intricate structures that would be challenging or impossible to achieve with traditional methods. 
  • Reduced material waste. Since 3D printing is an additive process, it generates minimal waste, contributing to sustainability goals and reducing material costs. 
  • Quick prototyping. 3D printing is exceptionally well-suited for rapid prototyping, allowing manufacturers to iterate designs quickly and cost-effectively. 
  • Customization. The flexibility of 3D printing allows for easy customization of parts, making it an excellent choice for one-off or low-volume production runs. 
  • Tool-less production. Unlike CNC machining, 3D printing doesn't require the use of complex tooling, resulting in reduced setup times and costs. 


Limitations of 3D printing

You might want to think again about 3D printing if any of the following factors are important: 

  • Surface finish. Depending on the technology and material used, 3D-printed parts may require additional post-processing steps to achieve the desired surface finish. 
  • Material limitations. While 3D printing with metals is increasingly common, the range of available metal materials may not be as extensive as those available for CNC machining. 
  • Build size constraints. 3D printers have limitations on build size, potentially restricting the size of the parts that can be produced in a single run. 
  • Production speed. While rapid for prototyping, 3D printing may not match the production speed of CNC machining for larger quantities. 

How to choose between 3D printing and CNC machining

Now that we know the pros and cons of both CNC machining and 3D printing, let’s explore some of the factors that may play into your decision between the two when producing your next metal part.

Nelson Miller Group samples of precision metal parts

Complexity of design

While CNC machining is ideal for parts with intricate details, tight tolerances, and complex geometries, 3D printing is well suited for complex and/or organic designs, enabling the creation of parts with internal structures and features that are challenging for traditional methods.

Material selection

CNC machining is suitable for applications where specific material properties are crucial, since it’s available in a wide range of materials. Although 3D printing doesn’t have as extensive of material options at this time, the list is constantly expanding.

Volume of production

If you need a large production run, CNC machining will be more cost-effective due to its efficiency and speed. For low-volume production, prototyping or customized, one-off parts, 3D printing is the way to go.

Time constraints

For a faster turnaround time, 3D printing allows for rapid prototyping and is ideal for certain production scenarios. CNC machining tends to have longer lead times, especially for parts that require multiple machining operations.

Cost considerations

Although setup costs will likely be higher for CNC machining, it becomes more cost-effective over large production runs. On the other hand, 3D printing is cost-effective at smaller quantities, and costs can escalate as production volumes get larger.

NMG is your trusted partner in precision manufacturing.

In the end, the choice between CNC machining and 3D printing is a nuanced decision that hinges on the specifics of your project. Each method has its strengths and considerations, and understanding your priorities and goals will guide you toward the optimal solution. NMG’s seasoned professionals bring a wealth of knowledge to the table, ensuring that your needs are met with precision and innovation. Whether you're seeking the unparalleled precision of CNC machining or the design freedom offered by 3D printing, our team can deliver a custom solution that aligns with your unique requirements.

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NMG has more than 85 years of experience partnering with organizations to bring their industrial, IoT, lighting, medical, telecommunications, consumer, and aerospace products to life. We solve your most complex challenges in engineering design, manufacturing, and supply chain management.  

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