CNC Turning vs. CNC Milling

In modern manufacturing, the ability to make precise parts quickly and with minimal variation is critical to proper fit and function. For many applications, precision machining is the most efficient way to do it.

Precision machining refers to a number of operations that remove material from a workpiece with high accuracy and within tight tolerances. Computer Numerical Controlled (CNC) machining equipment uses pre-programmed instructions to control and guide cutting tools without manual movements, resulting in very low error rates. CNC machining is also highly repeatable, since the machine will run the same program and make the same movements cycle after cycle until told to stop.

While CNC technology is compatible with many operations, we’ll focus on turning and milling here. For some applications, CNC turning and CNC milling can achieve similar features; however, the processes are not identical and are generally not considered interchangeable. Let’s look at their differences and similarities.

The Differences Between CNC Turning and CNC Milling

Like manual turning, CNC turning involves fixing a workpiece or blank to a chuck that rotates at high speed. Cutting tools are held perpendicular to the workpiece at different angles and locations to remove material and create peaks, valleys, and other details of the desired profile. Because the piece spins, the cutting action is distributed around the circumference of the piece. Turning is well-suited to parts that are cylindrical or round, with a uniform profile the entire way around.

In CNC milling operations, the workpiece is held stationary with jigs, chucks, and fixtures, while the cutting tools move into, out of, and around it. Many CNC milling systems use 3-, 4-, or 5-axis tools, which can cut and remove material from multiple angles without the need to reposition the workpiece. This reduces cycle time and the risk of error, since each time a piece is moved, there is a chance it will be misaligned. Milling can be used to create complex part features and profiles, including rounded corners, holes, grooves, notches, depressions or raised areas, and other shapes in thick metal workpieces of almost any shape.

Similarities Between CNC Turning and CNC Milling

Despite their differences, CNC turning and milling have similarities:

• In both of these processes, a CAD rendering of the part is used to determine the necessary toolpath, angle, and speed to create part features. The drawing is translated into CAM files and CNC instruction codes, also called G-codes, which guide the movements of the cutting tools in the machine. The machining process is highly automated, for fast cycle times.
• Because this kind of machining is semi- or fully automated, there is a low rate of error, especially those typically associated with manual processes like misaligned materials, incorrect tool angles, or mistakes due to fatigue. Parts made by CNC turning and machining tend to be more accurate and to hold tighter tolerances more consistently from part to part.
• Both operations can be integrated with automation and conveyance equipment, like robotic arms, material handling mechanisms, and vision inspection technology, which further reduces production time and mistakes.
• Because they work at high speeds and nearly continuously, heavy-duty CNC machinery can generate excess heat. To maintain production cycles and extend the service life of equipment and tooling, proper thermal management and lubrication are needed.
• There is also considerable overlap in the types of materials that are compatible with turning and milling operations, such as:
  • Aluminum
  • Copper
  • Steel
  • Titanium
  • Thermoplastics

Partner With Advanced Industries for Ultra-Precision CNC Turning and Milling

Both CNC turning and CNC milling are advanced manufacturing processes that can create precision parts at scale. Finding the right manufacturing partner is critical to the success of your application. Advanced Industries, Inc. provides custom, precision CNC turning and milling services, with multiple CNC equipment centers and in-house tool fabrication. We also offer design support for improved manufacturability and quality control management.

Learn more about us and why companies in many industries choose to work with us for their CNC turning and milling projects. Contact us today to learn more about our capabilities or request a quote to start your order.