3D Printing vs CNC Machining: The Great Prototyping Debate
It’s the first, most influential decision any designer will make. It’s a call predicated on many variables, namely, which process works best for your project.
It’s also the Number 1 debate in prototyping: 3D Printing & Additive Manufacturing vs. CNC Machining.
Each technology has its advocates. 3D Printing/Additive Manufacturing is a fast growing technology that is a 21st century upgrade over traditional manufacturing methods. CNC Machining (computer numerical control) is a proven subtractive technique for part creation.
Which of these computer-controlled methods is best for your business’ project in this Ali vs. Frazier-esque, Rocky Balbano vs. Apollo Creed-like prototyping matchup? The best way to find out is to review the tale of the tape and break down the pros and cons, advantages and disadvantages, and strengths and weaknesses of these two popular prototyping methods.
A Tale of Two Methods: Plus And Minus
The most glaring difference between the two methods is 3D printing is a form of additive manufacturing, while CNC machining is subtractive (The Plus-Minus Rule). CNC machining starts with a block of material (called a blank) and slices away material using cutters and spinning tools to create a finished part. This finesse rotating process allows for sharp dimensional accuracy as well as many compatible materials, including wood, metals and plastics.
In contrast, 3D printing creates parts layer by layer using materials such as plastic filaments (FDM), resin (SLA/DLP) and plastic or metal powders (SLS/DMLS/SLM). Hot energy sources like lasers or heated extruders are solidified to create the finished part. When it comes to accuracy, speed, freedom of shape, application in many sectors and ability to cut costs and weight in parts, 3D printing is the undisputed prototyping champion trusted by customers around the globe.
But this prototyping fight is far from over.
Material Conservation: Advantage 3D Printing
3D printers’ effectiveness in conserving materials while shaping prototypes make it more efficient in waste part reduction than CNC machining, which requires more materials for the mold to work.
The catch: 3D printers cannot work with every material that traditional manufacturers use due to high melting points. Some projects might not be compatible with 3D printing if they require specific materials that are incompatible with the printers.
The verdict in this matchup: 3D printing can’t beat CNC machining’s advantages for mass-produced items.
The Materials Check List
CNC machining’s compatibility allows it to work with a variety of materials, including:
- Metal alloys
- Modeling foam
- Machining wax
CNC machines boast heating systems that can manage heavy materials and build large-scale parts for engines, aircrafts and other machines. CNC parts must be exact, dependable and durable. The good news: most tools are standardized to fit any CNC machine.
While 3D printing is playing catch up in material variety and ability to withstand intense environments, 3D printers are now adding materials consistently, including metal alloy, wood fibers, thermoplastics and wax. 3D parts are now being used in intense environments like aircrafts and heavy duty machinery.
CNC machining delivers more precision and consistency because of its higher tolerance for heat. But 3D printers offer precision and part consistency. Plus, 3D printers offer an extreme advantage in user-friendliness. When CNC machines malfunction, they require troubleshooting, which means production of unusable products.
The verdict: A draw.
Versatility: A Draw
You name it, CNC machines can produce it. Fixtures, tools and custom-designed parts can be fashioned thanks to CNC machines’ wide range of quality settings. CNC machines quickly build designs so developers can test them. 3D printers can match this quick efficiency.
Again, when it comes to speed, 3D printing is a road runner, allowing you to quickly build designs for testing. With CNC Machining, you have to set up the tooling each time you change your design. The result: Time-consuming, expensive retooling.
Project Cleanliness: Advantage 3D Printing
The basic natures of subtractive and additive methods makes CNC machining much nosier and messier than 3D printing due to its use of a tool to cut away material. Tools make noise and leave a lot of scrape metal or wood shavings in their creative wake. CNC machining needs to be conducted in a remote work setting where it won’t disturb people.
Meanwhile, 3D printers quietly uses only the material it needs to complete the project. Plus, working like a church mouse, 3D printers don’t vibrate like CNC machines.
Prototype Integrity: Advantage CNC Machining
CNC machines don’t heat material and reform it. The material remains stronger and with better structural integrity than most 3D printers.
However, cutting edge 3D printers like Rapids Reproductions’ Markforged printers can produce plastic composite parts that are as strong as aluminum. Plus, the new Metal X printer sinters the metal parts isotopically and boasts superb structural integrity. Today’s 3D printers also do not need to add foreign materials.
Older 3D printers also may need to add foreign materials to the mixture to finish the prototype, a lengthy process CNC machines don’t require.
CNC machines’ simple prototype creation process also provides the a better surface finish than some 3D printers because materials don’t deform during the process. Their rigid material and cutting action keeps the form together, allowing for fewer chances for mistakes and deformations to occur. Aging 3D printers models may have a poorer surface finish because of their layered heated plastic.
But professional 3D printers eliminate the issue of warping, bending and distortion from the prototype process.
Here’s The Final Tale of the Tape for 3D Printing vs. CNC Machining before we go to the judges.
3D Printing Wins On:
- Easy to use: easy to prepare for an operation.
- Part complexity does not affect the price of the part.
- The limitless capacity to create products with intricate designs.
- Price constant regardless of the batch size.
- Flexibility to quickly change production jobs.
CNC Machining Wins On:
- A broad selection of materials to use for production.
- Freedom to choose the resolution of production in exchange for speed or cost benefits.
- Superior quality surfaces and high precision.
- Price constant regardless of the product size and volume.
- Low-cost machinery and supplies.
The Decision: Who’s The Victor?
World Finance’s verdict is clear: 3D printing is not a solution that can replace CNC machining. 3D printers can greatly improve certain aspects of manufacturing, but cannot provide solutions for the whole market. CNC machining works better and offers finer quality in many situations than 3D printers.
Plus, CNC machining is unbeatable for large-scale production.
But for smaller production scales, 3D printers are the winning pick to save businesses money from buying expensive molds. 3D prototypes offer insight into the product’s shape and aesthetic. For minor scale projects, Markforged 3D printers are universally trusted by designers working on a budget.
“You can look at spending thousands and thousands of dollars to have these machined or produced on the outside, or you can look at the ability to do them in-house for literally tens or hundreds of dollars,” Kris Sullenberger of Humanetics said in an endorsement of 3D Printing.
In many areas, CNC technologies and 3D Printing/Additive Manufacturing overlap in capability, but their individual strengths make them suitable for specialized applications. CNC Machining is the best method for large-scale, sophisticated, high-precision products made from readily available materials. 3D printing is the go-to method for custom-designed, small scale projects requiring multiple prototypes to ensure product integrity.
In the end, this fight is a draw. Your project’s needs will determine which is the winning method for you.