What is a Turning Operation in CNC Machining?(cnc machine tooling Quintina)
- source:BAGANZ CNC Machining
Turning is performed on a lathe machine, which holds the workpiece firmly and rotates it at high speeds while the cutting tool feeds into the material. By precisely controlling the movement of the cutting tool and the rotation of the workpiece, intricate features and shapes can be machined with excellent accuracy and repeatability.
Here are some key things to know about CNC turning:
How Does Turning Work?
In its basic form, turning involves rotating a cylindrical workpiece while a stationary cutting tool is fed horizontally into it, gradually removing material. The cutting tool’s sharp edge shears away a thin chip of material with each pass along the workpiece. As material is removed and the diameter gets smaller, the workpiece continues rotating at a constant speed while the tool progressively feeds closer to the center axis.
This turning process can create cylindrical shapes such as rods, shafts, spindles, disks, and pulleys. By moving the cutting tool in different patterns, various features like grooves, shoulders, holes and chamfers can also be machined. The key parameters such as cutting speed, feed rate, depth of cut and tool path pattern all play a role in the turning process.
Types of Turning Operations:
Outside diameter (OD) turning – The most common operation which reduces the outside diameter of a cylindrical workpiece. The cutting tool faces outward from the workpiece center.
Inside diameter (ID) turning – Also known as boring, this involves cutting along the interior diameter to enlarge the size of holes or produce an internal cylindrical shape. The cutting tool faces inward toward the center.
Facing – Machining the flat end surface of a cylindrical workpiece perpendicular to its center axis. This creates a uniform, smooth finish on the face.
Parting and grooving – Narrow grooves and recesses can be cut into the workpiece by feeding the tool radially across the rotating part. Parting is a similar operation that cuts deeper grooves to separate a workpiece into two parts.
Threading – The cutting tool can machine screw threads by moving in a helical motion synchronized with the workpiece rotation. Single-point threading tools produce internal and external threads.
Taper turning – The workpiece diameter is reduced gradually along its length to create a tapered shape. This requires the cutting tool to be set at an angle offset from perpendicular to the workpiece centerline.
Profiling – Complex rotational contours, shapes and 3D profiles can be machined by precisely controlling the motions of the cutter combined with the angle and rotation of the workpiece.
Machining Parameters in Turning:
Cutting speed – The surface speed at which the workpiece material moves past the cutting tool, usually measured in feet per minute (SFM).
Feed rate – The rate at which the cutter advances horizontally into the workpiece as it rotates. Measured in inches per revolution (IPR).
Depth of cut – The radial distance from the original workpiece diameter to the cut surface, defining how much material is removed. Measured in inches.
Cutting tool – Carbide insert cutters are commonly used, featuring a replaceable cutting insert made of an extremely hard material with a sharp cutting edge. The tool geometry and angle is selected based on the workpiece material.
Coolant – High pressure coolant fluid is applied to the cutting area to cool the tool, reduce heat and flush away metal chips. This improves finish, prolongs tool life and overall accuracy.
Material – Common workpiece materials include aluminum, steel, stainless steel, titanium, brass, plastic and wood. The material influences tool selection, machining parameters and surface finish.
Tolerances and surface finish – CNC turning can consistently achieve very tight dimensional tolerances with excellent surface finishes. Typical tolerance values range from ±0.005 in to ±0.0005 in depending on requirements. Finishes under 10 microinches are attained.
Automating Turning on a CNC Lathe:
CNC (Computer Numerical Control) lathes allow turning operations to be automated through programmed control. Here are some key advantages of CNC turning:
Precision and Accuracy – CNC machines the workpiece based on CAD dimensions, enabling parts to be machined to tight tolerances of 0.0002 in or 0.005mm repeatably. Machining errors are eliminated.
Complexity – Intricate part geometries, shapes and profiles that would be infeasible to produce manually can be machined through 3D CAM programming and 5-axis CNC turning.
Automation – Once the CNC program is proven out, the machine can run unattended and make hundreds or thousands of identical parts in a streamlined production workflow.
Speed – CNC turning is significantly faster than manual operation, with extremely high cutting speeds, feeds and depths of cut possible. Cycle times are reduced.
Reliability – CNC eliminates variability and defects making every part uniform in quality. Scrap and rework caused by human errors are minimized.
Flexibility – Quick changeovers between jobs allow high mix, low volume production. CNC programs can be easily edited and optimized.
In summary, turning is an essential machining process that utilizes single-point cutters and lathe machines to produce precise round, cylindrical shapes. It can manufacture myriad components used in motors, engines, pumps, gears, axles, pipes, bushings, disks and more. The versatility of CNC turning makes it one of the most commonly applied subtractive manufacturing processes for metal and plastic parts across all industries. With programming, automation and precision impossible through manual approaches, CNC turning is a modern manufacturing solution. CNC Milling