CNC Machine vs. 3D Printing: Comparing Old and New Technology

Background

Manufacturing has evolved rapidly in the last century. From Henry Ford’s installation of the first assembly line in 1913, to the current practice of producing everything in foreign countries, the goal has been to save time and money.

CNC machining and 3D printing are two common methods for creating custom parts. Both utilize computer numerical control (CNC) to work. CNC came from the numerical control method, which developed from traditional milling after WWII. Both CNC machining and 3D printing have their place in the industry, each with benefits and drawbacks.

CNC Machine

Benefits

CNC subtractive manufacturing has a few benefits. It allows machinists to have precision with speed, designers to have variety in their designs, and faster production than previous milling methods. It can be applied to creating custom end-use parts as well as tooling and fixturing.

CNC subtractive manufacturing produces strong custom end-use parts.

Drawbacks

Although the CNC machine was revolutionary when first developed, newer technologies draw attention to some of its drawbacks. This method tends to be very expensive. From the expense associated with the machine itself to paying a qualified machinist for good work, the costs are high. Costs also increase as parts become more complex. In addition, in order to manufacture the end-use custom parts, time must be taken to create support parts. Therefore, a designer not only needs to pay a machinist to create the part they want, but also clamps, jigs, and other pieces necessary for manufacturing. Finally, prototyping becomes increasingly difficult as each iteration can take weeks to produce.

3D Printing

Benefits

3D printing has been around for 30 years, but has recently become much more practical from a cost/value standpoint. It is the simplest way to go from a computer aided design (CAD) to physical part. It has the ability to print parts in a matter of hours, making iteration and testing easier for designers. The cost is also significantly reduced as printers are available in a wide variety of price points. Plus, the printing materials used tend to be cheaper, and there is no need to hire someone with special skills to operate the printer.

3D printing is ideal for designs that require multiple iterations.

Drawbacks

This revolutionary tool is great for iterations, but there are still some drawbacks. Unfortunately, printing materials are usually relatively weak or fragile plastics. Traditionally, this has meant that printed parts cannot be made for actual use, only for fit, feel and limited testing. However, many companies (such as MarkForged) are developing stronger materials such as composite parts made from durable nylon and carbon fiber or fiberglass. These parts can be used in production and can have higher strength to weight ratios than aluminum!

Keep in mind that 3D printed parts are printed layer-by-layer so they are anisotropic, which can be problematic in testing.

So which method is better?

The answer is neither. Both additive and subtractive methods have benefits and drawbacks, so ideally these machines can be used in tandem to streamline the design process. 3D printing, for now, is unable to replace traditional CNC subtraction methods, since most final custom parts need to be made of metal, a material that only very expensive laser-sintering printers can print with.

However, 3D printers can easily create iterations for some testing before designs are sent to a subtractive CNC manufacturer or traditional molding production. 3D printers can also print supportive jigs and other parts needed for the expensive milling machines. This means that mills and machinists can focus on the end use products, rather than spending time creating supporting parts. Lastly, 3D printers have the ability to print complex geometries for jigs that were previously impossible with traditional milling methods.

Subtractive CNC manufacturing and 3D printers complement each other to streamline the design process.

Better Together

Overall, bringing together traditional CNC subtractive methods with 3D printing can decrease costs, reduce production times, and streamline the entire design process.

Want to know more about how to maximize design and manufacturing efficiency by combining the best of 3D printing and traditional manufacturing processes? Check out one of our webinars or contact us for a free consultation with one of our manufacturing and design experts!

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