What is a Turning?(bead blast vs sand blast Selena)
- source:MAJA CNC Machining
How Does Turning Work?
In turning, the cutting tool is held stationary while the cylindrical workpiece rotates at high speeds. The cutting tool feeds linearly into the workpiece, removing material as it moves. As the workpiece rotates, the entire circumference of the part comes into contact with the cutting tool, allowing cylindrical features to be machined.
The turning operation takes place on a lathe, which holds the workpiece firmly in place between two centers or in a chuck. Power is transmitted to the workpiece via the spindle, causing it to rotate at the desired speed. The spindle can be oriented either horizontally or vertically depending on the orientation of the lathe.
As the workpiece rotates, the cutting tool is slowly fed into it at a specific rate and depth of cut. The linear movement of the tool along the axis of the workpiece creates the cylindrical features. Coolant is often applied to wash away chips and keep the tool from overheating.
Types of Turning Operations
There are several basic turning operations that can be performed:
- Facing - Machining the end of a cylindrical workpiece flat and perpendicular to the axis of rotation. This creates a smooth reference surface.
- Straight turning - Reducing the diameter of a cylindrical workpiece to a specific dimension along a portion or all of its length. This can be done as a roughing pass to remove bulk material or a finishing pass to achieve high accuracy.
- Taper turning - Machining a tapered feature by gradually decreasing or increasing the diameter along the length of the workpiece. This requires the tool to be set at an angle offset from perpendicular to the spindle axis.
- Grooving/parting - Cutting grooves or deep channels into the workpiece. Parting is a grooving operation that cuts entirely through the workpiece to separate a part.
- Boring - Enlarging the internal diameter of a hole in a workpiece. The boring tool must be fed radially into the hole, rather than parallel to the axis as with external turning.
- Threading - Cutting screw threads into or onto a workpiece using a threading tool. The complex cutting action requires coordinated rotation and linear motion between the tool and workpiece.
- Form turning - Using a shaped tool to machine complex contours across the face of the workpiece. The tool follows the contour shape as the part rotates.
- Chamfering/filleting - Adding a chamfer (beveled edge) or fillet (rounded corner) to the workpiece. Special chamfering and filleting tools are used to create these features uniformly around a diameter.
Advantages of Turning
There are several key advantages that make turning one of the most prevalent manufacturing processes:
- Versatility - Turning can produce a wide variety of geometric features on both external and internal surfaces. Complex parts can be machined entirely through turning operations.
- Precision - Modern CNC lathes can hold extremely tight dimensional tolerances down to ±0.001 in or less. Smooth surface finishes down to 4-8 microinches RMS are possible.
- Efficiency - The high cutting speeds and feed rates used in turning mean a lot of material can be removed quickly. Setup time is low compared to milling operations.
- Cost Effectiveness - Turning is very economical for mass production. CNC automation reduces labor costs and allows 24/7 operation. The lathe itself has relatively low maintenance costs.
- Surface Finish - The orthogonal cutting action of turning produces an inherently high-quality surface finish. Reduced vibration from the rotating workpiece also improves finish.
Turning is used across almost every industry that employs machining to make parts. Some common examples of turned parts include:
- Engine cylinders, pistons, crankshafts and camshafts in automotive and aerospace applications
- Wheels, rollers, spindles, axles and shafts in machinery and equipment
- Bolts, screws, nuts and fasteners in both standard and custom sizes
- Valve bodies, couplings, fittings and adapters in fluid power systems
- Extruder barrels, mixer shafts and worm gears in plastic processing and material handling equipment
- Bone screws, hip joints and surgical instruments in medical device manufacturing
- Shell casings, gun barrels and armor piercing projectiles in the defense industry
From tiny precision turned pins and bushings to massive rollers turned from solid steel, turning can produce almost any cylindrical part. Engineers rely on it as an indispensable manufacturing process. When coupled with milling and other secondary operations, turned parts can be machined into complex components critical to the performance of advanced mechanisms and assemblies. The unparalleled versatility of the turning process will ensure it remains a vital part of manufacturing for the foreseeable future. CNC Milling CNC Machining