Let's learn something about cutting tools today.

What is Cutting tool?

Cutting tool is a wedge shaped and sharp edged device that is used to remove excess layer of material from the workpiece by shearing during machining in order to obtain desired shape, size and accuracy. It is rigidly mounted on the machine tool. A relative velocity between workpiece and cutting tool is also provided by various mechanical and other arrangements for cutting action.

Examples of cutting tools

Cutting tool is basically the cutter used in machining operation. Various machining operations utilize different cutters and thus various names are available for these cutters based on the application. A list of commonly used cutting tools is provided below.

1. Single point turning tool—cutter for turning operation performed in lathe

2. Drill—cutter for drilling operation performed on drilling machine or lathe or milling machine

3. Milling cutter (or mill)—cutter for milling operations performed on milling machine

4. Fly cutter—cutter for fly milling operation performed in milling machine

5. Shaper—cutter for shaping operation performed in shaping machine

6. Planer—cutter for planing operation performed in planing machine

7. Boring bar—cutter for boring operation performed in drilling or boring machine

8. Reamer—cutter for reaming operation performed in drilling machine

9. Broach—cutter for broaching operation performed in broaching machine

10. Hob—cutter for hobbing operation performed in hobbing machine

11. Grinding wheel—abrasive cutter for grinding operation performed in grinding machine.

Materials of cutting tool

During machining, part of the cutting tool remains in physical contact with the workpiece and thus experiences severe cutting temperature and insistent rubbing. The material of the cutting tool must have the capability to sustain such high cutting temperature as well as cutting force. Every tool material must possesses certain properties such as high hardness, high hot hardness, high strength, higher melting point and chemically inert even at high cutting temperature. As a thumb rule, the hardness of the tool material should be at least 1.5 times of the hardness of the workpiece for smooth cutting action.

Suitable coating can also be applied on the tool to improve various desired properties. However, a coated tool does not allow easy re-sharpening by grinding when the edges are worn out after prolonged use. Now-a-days, insert based tools are available where small interchangeable inserts can be attached or clamped on large shank. These inserts perform cutting action and thus worn out gradually. When wear exceeds the tolerable limit, the inserts can be replaced by a new one, while the shank can be used repeatedly. Some of the tool materials commonly available in todays’ market are enlisted below.

High Speed Steel (HSS)

Tungsten carbide

Ceramics

Cubic Boron Nitride (cBN)

Diamond

This article is just a basic introduction of common cutting tools in machining industry, we will talk about more about this topic in future.