5 Most Common Myths About CNC

Fast Radius reveals what engineers should know about CNC machining.

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Written by: Cory Cetkovic, Manager, Manufacturing Engineering, Fast Radius

(Image courtesy of Fast Radius.)

(Image courtesy of Fast Radius.)

Computer Numerical Controlled (CNC) machining is a subtractive manufacturing process that produces a part by systematically removing layers of material from a single block of metal or plastic. Since CNC machining is largely computerized, it is known for producing highly precise and complex parts with tight tolerances.

CNC machining is not new, but there is still some confusion about how it works. There are many different types of CNC machining out there, and it can be challenging to get the facts straight.

Here are five of the most common myths about CNC machining that engineers should know—and the truth about CNC machining.

1. CNC Machining is Expensive

In the early 1950s when CNC machining was just emerging, it was more challenging and more expensive for engineers to access the software needed to power CNC machines. The widespread availability of Computer-Aided Manufacturing (CAM) software has dramatically driven costs down. Another factor driving costs down is the technological advancement of CNC machines themselves. Now, they feature more built-in automation which reduces cycle and labor times.

Further, CNC machine operating costs are moderate to low in comparison with other manufacturing methods. For example, a 3-axis CNC machine typically costs $40 per hour in the United States, excluding the cost of skilled labor. Acrylonitrile butadiene styrene (ABS), one of the most popular materials used in CNC machine parts, costs around $17 per 6” x 6” x 1” sheet. If engineers divide these costs over a high volume product production run, they will find that CNC machining is among the most cost-effective manufacturing solutions.

2. CNC Machining is Completely Automatic

Many people hear “computer-controlled” and think that CNC machining is a “set it and forget it” solution. It is true that significant advances in automation have been made and that a computer does most of the heavy lifting in the CNC machining process, but it would be inaccurate to say that engineers can push a button, walk away from the machine and come back to a flawlessly executed part.

If the machine tools shift out of place during processing, skilled CNC professionals will have to recalibrate them. To keep a CNC machine humming, CNC machinists must monitor cycles, measure workpieces, replace dull tools and engage in other critical maintenance activities. CNC machining isn’t fully automatic, but with a skilled machinist to monitor production, near-uniform quality can be attained.

3. CNC Machining is Too Slow

In addition to making CNC machining more affordable, recent technological advancements have also made it faster. CNC machining can yield low volume production runs in as fast as a week depending on the specific technology used. Since CNC machining is reliable for creating high-quality repeatable parts, this process also makes it easier for engineers to calculate production times and stick to project timelines.

4. CNC Machining Does Not Enable Design Innovation

Contrary to popular belief, this computer-controlled manufacturing process is not limited when it comes to design capability. Designers often turn to CNC machining when they want to use master patterns for niche builds that could not be created using any other process. CNC machining is also uniquely capable of creating intricate designs, angular cuts and free-form geometric designs.

The Computer-Aided Design (CAD) models loaded onto the CAM software prior to manufacturing enable engineers, designers and product managers to create parts with complex geometries and one-of-a-kind parts—and modify them at speed. Also, the list of materials available for CNC machining is extremely large. Using CNC machining, designers have an abundance of opportunities to innovate without sacrificing strong mechanical properties.

5. CNC Machining is Yesterday’s News

The manufacturing industry is constantly evolving, but CNC machining is still incredibly relevant. CNC machining is extremely complementary to additive manufacturing, especially when it comes to additive metals.

In addition to producing high-quality precision parts, CNC machining can make precision tasks such as engraving, shearing, stamping, tuning and boring easier and faster. Most CAM software updates automatically so engineers will always have access to the latest CNC programming. What’s more, CNC machining is compatible with a wide variety of materials and even some precious metals such as gold and silver, giving engineers and designers plenty of options.

The process also has wide-ranging use-cases in numerous industries, and due to its inherent adaptability, is able to meet stringent standards in heavily regulated industries such as aerospace. The Federal Aviation Administration (FAA) has some of the strictest mechanical and structural standards of any industry, and aerospace engineers trust CNC machining to produce the precision parts needed for aircraft turbine engines.

CNC machining is a reliable and cost-effective traditional manufacturing process that nicely complements additive manufacturing. Dispelling myths about CNC machining like those above ensures that engineers and product managers don’t miss out on an opportunity to innovate.

To learn more, visit Fast Radius.