Machining processes are used in the manufacturing industry to selectively remove material from a workpiece. It’s considered a type of subtractive manufacturing because it creates new objects through the act of material removal. As the machining process removes material from the workpiece, it creates a new object in the desired shape. This is in stark contrast to additive manufacturing, which involves the addition of material to create new objects.
While all machining processes rely on the removal of material to create new objects, the way in which they perform this task varies. Most machining processes fall under one of three categories, each of which uses a different method to remove material from a workpiece.
Turning is a machining process in which a fixed, non-rotating cutting tool removes material from a rotating workpiece. The cutting tool itself remains stationary, but the workpiece rotates around it to facilitate the controlled removal of material. Although it can be performed manually by hand, turning operations are typically performed using a machine known as a lathe.
There are four different types of lathes using for turning operations, including the following:
- Straight turning lathe
- Profiling turning lath
- Taper turning lathe
- External grooving lathe
Milling is a machining process involving the use of a rotating cutting tool to remove material from a stationary workpiece. Milling cutting tools have “teeth” that rotate while grinding against the surface of the workpiece. Of course, only certain areas of the workpiece are exposed to the cutting tool, allowing companies to create objects in complex shapes using this machining process.
The main difference between turning and milling is that the former involves the rotation of the workpiece, whereas the latter involves the rotation of the cutting cool. Additionally, turning operations use a smaller cutting tool consisting of a single sharpened blade, whereas milling operations use a collection of teeth-like blades to grind against the workpiece.
The third type of machining process is drilling, which as you may know, involves the removal of material from a workpiece by cutting holes with a rotating cutting tool. Unlike with most milling and turning operations, the cutting tool used in drilling has multiple points. As a result, it’s able to dig deep holes into workpieces, with the cutting tool rotating at rates of up to 2,000 revolutions per minute.
While effective at creating deep holes, drilling can stress the structural integrity of a workpiece. As the cutting tool digs into the workpiece, it may create micro-sized cracks surrounding the newly created hole.