CNC Machining vs. 3D Printing: What’s Best for Your Business?

The reduction in cost and time offered by 3D printing technologies has become a major benefit that many industries cannot afford to ignore. But both CNC machining and 3D printing have unique strengths and applications, making them suitable for different scenarios. This overview explores their differences, advantages, and costs, with the aim of helping you make an informed decision for your business.

Understanding CNC machining and 3D printing

CNC machining

CNC (computer numerical control) machining is a subtractive manufacturing process that uses pre-programmed software to control machinery. It is renowned for its precision and ability to work with a wide range of materials, including metals and plastics.

3D printing

3D printing, or additive manufacturing, builds objects layer by layer from digital models. It is highly versatile, capable of producing complex geometries with minimal waste.

Key differences between CNC machining and 3D printing

Aspect	CNC Machining	3D Printing
Process	Removes material from a solid block	Builds layer by layer from digital model
Accuracy	High precision and repeatability	Good for complex geometries less precise
Material Waste	Generates more waste	Minimal waste, more sustainable
Complexity	Requires skilled operators and setup	Easier setup, often automated

Accuracy

While metal 3D printing, in particular, can be associated with thermal distortion, cracking, and other defects. Thankfully, there are now software technologies to help 3D printing engineers simulate, predict, and reverse potential defects in advance. These software improvements have the capability to entirely negate past inaccuracies.

Material waste

3D printing generates less waste as material is usually fed, and any leftover material can be recycled. This makes it cleaner than CNC, which typically involves cutting from a material and creating. However, 3D printing is limited to the build size. So, when it comes to the maximum size of parts, 3D printing cannot compete well with CNC. There is almost no limit to the type of material that can be used in 3D printing, such as plastic and metal. There are 3D printing examples of food, chocolate, vitamins, and even human tissues. Although CNC can be used for a wide range of materials, there are still materials that CNC cannot do, such as certain super alloys.

Complexity

Pre-programmed CNC machining can turnaround complex projects speedily. But, one of the main advantages of 3D printing is its ability to handle almost any complex geometry. This reduces the number of parts that are usually needed in an assembly when using CNC. So, for complex parts that are difficult to manufacture, 3D printing must be considered first. An added bonus is that there are now software technologies that take advantage of this feature to help designers choose the minimum weight and optimum stiffness through topology analysis before printing. 3D printing technologies differ in terms of the tolerances they can handle. And CNC is generally considered superior. Although, when considering the minimum layer thickness achieved by some 3D printing technologies, this advantage becomes less noticeable.

Cost

This is largely dependent on the volume of printing and related to the speed of delivery. Therefore, for low quantities (i.e., in the 100s), 3D printing offers lower costs, and it is faster. Other factors require further consideration, such as CNC parts repair and replacements. But for large quantities, of 500 and more, other manufacturing should also be considered, such as casting.

Industry applications: CNC machining vs. 3D printing

Aerospace

CNC machining aerospace components

CNC machining is used to manufacture critical components such as turbine blades and engine parts. For example, you might use CNC machining to produce titanium engine brackets that must withstand extreme temperatures and stresses during flight.

3D printing aerospace components

Airbus uses 3D printing to produce full-scale aircraft interior prototypes, significantly reducing lead times and costs. This in-house 3D printing process allows rapid design iteration, eliminating the need for costly molds and enabling efficient exploration of innovative designs.

Automotive

CNC machining automotive components

CNC machining is used for parts that require tight tolerances and high strength, such as transmission housings and brake components. For example, you can use CNC machining to create aluminum alloy wheels that offer both strength and lightweight performance.

3D printing automotive components

Swedish automotive manufacturer, Koenigsegg 3D printed the turbocharger for the world’s first series-produced megacar. The One:1 produces one Megawatt of power and is named after its astonishing ratio of hp-to-kg.

Healthcare

CNC machining surgical tools and implants

CNC machining is used for producing surgical instruments and orthopedic implants, where precision and biocompatibility are essential. For example, you could use CNC machining to fabricate stainless steel surgical tools that require exact dimensions for safe and effective use.

3D printing patient-specific implants and prosthetics

Customization is a significant advantage in the medical field. 3D printing allows for the production of patient-specific implants and prosthetics. For instance, 3D printing enables manufacturers to create custom-fit implants tailored to a patient’s anatomy, enhancing comfort and functionality.

Summary

The choice between 3D printing and CNC is highly dependent on the materials in use, the number of parts, speed of delivery required and geometrical complexity. In recent years, 3D printing has become more and more accurate, with build sizes also increasing, and print times improving.

How can TECHNIA help?

We provide CNC machining services, knowledge, and support for mold, press, and cast tooling, ensuring successful machining processes through simulation and analysis. Our CNC services are tailored to your environment, using existing tooling libraries and machine parameters to efficiently extend existing capabilities. For 3D printing, or additive manufacturing, we provide optimized generative design, simulation, and analysis, enabling clients to explore and refine 3D printing processes before full-scale implementation. And, in collaboration with Renishaw, we offer a secure development environment for metal additive manufacturing. This includes access to the latest AM systems and expert guidance to integrate 3D printing technology into business operations.