What is CNC Turning?
CNC Turning is a manufacturing process. Metal bars are held and rotated while a tool removes material to create a shape for the CNC-turned components. CNC turning involves holding the workpiece in a horizontally-mounted, adjustable spindle. The piece rotates on a lathe, allowing a computer-controlled turret with attached tooling to cut the material into a specified shape based on programmed instructions.
A center with both turning and milling capabilities can stop rotation to allow for milling out of other shapes. Turning parts on CNC turning centers allows for a wide range of complexities, sizes, and material types.
The starting material can be round, square, or hexagonal-shaped. Bar length is based on the feeder. The tools in CNC lathes or CNC turning centers are digitally controlled. CNC lathes and CNC turning centers can utilize a variety of processes to create different end results.
What is the History of CNC Turning?
The process of CNC turning is actually based on one of the oldest machining tools in the world, the lathe. In fact, the use of a lathe in manufacturing dates back to Ancient Egypt.
Fast forward several centuries to the late 1940s and numerical controlled (NC) machining was invented by John T. Parsons, who was working in conjunction with the Massachusetts Institute of Technology.
Commissioned by the US Air Force, Parsons was tasked with finding the most cost-effective way of producing aircraft parts that fit intricate specifications. Thanks to his efforts, CNC machining soon became the norm in the CNC manufacturing industry.
Then in 1967, the idea of computer-controlled machining first started circulating. A full nine years later, the first 3D computer-aided machining systems became available and within 13 years after that, CNC turning and machining became the industry standard.
How Does CNC Turning Work?
The CNC Turning process involves the raw material being secured and turned by the lathe while a single-point cutting tool is moved parallel to the axis of rotation, thereby shaping the material.
The exact measurements are fed into a machine via CAD software. Once the computer has read the instructions, it controls the lathe to ensure that the machined parts are manufactured to the exact specifications required.
This is different from conventional machining since it is the workstation that rotates rather than the cutting tool. Because of how they operate, CNC turning is typically used to make more cylindrical or oblong-shaped components.
The technique is also chosen ahead of CNC Milling and 3D printing because of its ability to produce multiples of the same component quickly and from one single piece of raw material.
What are the Advantages of CNC Turning?
CNC turning is the fastest way to remove extensive material on rounded stock.
CNC turning is the only industrial process to choose when making production volumes of concentric shapes or threaded features.
And, because of the rigid construction of a CNC lathe, there is little vibration, which means turning in machining can offer high levels of dimensional accuracy with excellent surface finishes.
When compared with manual turning, CNC turning offers abundant advantages over traditional manual fabrication methods, including:
- Quick Turnaround. CNC turning equipment is pre-programmed and allows the equipment to move more quickly than manual machining.
- Superior Precision. Pre-programmed specifications ensure preferable precision and reliability.
- Variable Production Sizes. Faster CNC turning allows for larger-scale production with high repeatability.
- Material Versatility. CNC turning can be used on a broad range of materials.
- Enhanced Worker Safety. CNC turning requires less direct human interaction, thereby reducing the risk of injury to workers.
- Cost-Effectiveness. Enhanced speed and reduced labor costs can make CNC turning very affordable in comparison with other manufacturing.
What Materials Can be Processed by CNC Turning?
Such as aluminum, a variety of mild and stainless steel, titanium, magnesium, brass, copper, and other alloys can be processed by CNC turning.
Note that some tool steel may be too hard to cut on a lathe or mill or else will require special treatment and a longer production time. Soft elastomers or plastics may also be impossible to turn since they cannot be held in a fixed position or would change in shape under the pressure of the cutting tool.
CNC Turning is an extremely versatile manufacturing process. While it is mostly associated with the automotive, aerospace, and engineering industries, it can also be used to create objects like pieces of art and ornaments.
What Parts Can be Made by CNC Turning?
Example CNC turning parts include:
- Rollers: CNC lathes can fabricate rollers with tight tolerances for industrial use
- Ball joints: CNC turning is ideal for rounded connective devices like ball joints
- Nuts and bolts: The accuracy of turning makes it suitable for tolerance-critical items like nuts and bolts
- Shafts: Shafts with rounded profiles are highly suited to CNC turning
- Flanges: CNC-turned flanges can strengthen beams and pipes
- Nozzles: Nozzles are typically cylindrical or conical with hollow insides, making them suitable for CNC turning
- Turbines: CNC turning can produce round turbine blades for the energy industry
- Firearms: A CNC lathe can produce the tubular shape required for a firearm barrel
Application Field of CNC Turning
- Aerospace. CNC turning is critical to the manufacturing of high-precision parts, engines, and aircraft bodies for the aviation industry.
- Medical and dental. Turning produces precise measurements, points, and angles for tools and instruments used in the dental and medical fields.
- Automotive. CNC turning quickly creates precise shafts, valves, and other precision-turned parts for consumer, commercial, and defense vehicles to keep up with industry demands.
- Electronics. CNC turning is capable of producing the highly complex and precise precision-turned parts needed to manufacture computers and other electronics.
- Military. Turning can machine parts to high standards with precise tolerances for military vehicles, avionics, and other military equipment.
Types of CNC Turning Processes
There are several types of CNC turning processes, each of which performs different tasks to reach an expected outcome. While none of these CNC turning processes achieve much separately, mixing and matching them all and incorporating computer programming results in high-quality CNC turning parts. Some primary types of turning include:
- Straight or cylindrical turning. This type of CNC turning uses a uniform motion to decrease the working diameter to prevent variation of the cut. This process removes large amounts of material from the workpiece before it undergoes more precise cuts. This CNC turning process creates a narrow cavity by pressing a shaped tool into the material.
- Taper turning. Taper turning creates a cylindrical shape with a gradually decreasing diameter. Often performed on materials that need extra grip, this CNC turning process cuts a serrated pattern into the workpiece.
- Spherical generation. This CNC turning process results in a perfect sphere shape by turning the workpiece around a fixed axis of revolution.
Precision CNC turning is capable of producing precision-turned parts, such as screws, motor shafts, and more, for the mechanical industry that meets the necessary technical specifications. The highly precise nature of CNC turning also makes it suitable for woodworking, certain electrical applications, and electrical discharge machining (EDM).