CUTTING TOOLS

Cutting tools are wedge-shaped, sharp-edged tools used during machining to cut extra layers of material from a workpiece to achieve the desired shape, size, and accuracy. It has a secure connection to the machine tool.

In addition, mechanical and other mechanisms provide a relative velocity between the workpiece and the cutting tool. The tool must be able to endure the heat and force produced during the machining process, and the cutting tool material must be harder than the material being cut (workpiece).

Materials of Cutting Tools

The cutting tool part experiences high cutting temperatures and continuous rubbing while machining because it remains in direct physical contact with the workpiece. The material used to make the cutting tools must possess the strength to withstand such high cutting temperatures.

The following is a list of some of the most common cutting tool materials:

1. High-Speed Steel (HSS)

2. Tungsten carbide

3. Ceramics

4. Cubic Boron Nitride (CBN)

5. Diamond

Classification of Cutting Tools

A cutting tool might have one or more cutting edges that take part in simultaneous cutting in a single pass. The most popular method of classifying a cutting tool is based on how many major cutting edges are actively engaged in the cutting process at any given time.

Based on this, the cutting tool can be divided into the three categories listed below. 

1 Single Point Cutting Tool

A single-point cutting tool only has one main cutting edge that can remove material in one motion. In turning, shaping, planning, and related processes, a single-point cutting tool is employed.

High-carbon steel, high-speed steel, ceramic, and diamond are some of the hard materials used to make these cutting tools. Since a single cutting edge does all the work, materials might not be removed quickly with a single-point cutting tool, and the cutting edge might even break.

You must stop using the tool and replace it entirely if a cutting edge breaks while you’re using it. A single-blade reamer is an example of a single-point tool with just one cutting edge.

Advantages of Single Point Cutting Tool

1. Single-point cutting tools are relatively easy to design and make, and they take less time.

2. These tools are considerably less expensive.

Disadvantages of Single Point Cutting Tool

1. During machining, a single cutting edge maintains constant physical contact with the work material. As a result, tool life is short due to the high tool wear rate.

2. The rate of rise in tool temperature is high due to constant contact. This has the dual effects of accelerating tool wear and heating the machined surface.

3. The high-temperature rise may cause the tooltip to deform plastically, reducing machining accuracy.

4. The material removal rate (MRR) is much lower because only one cutting edge uses the entire depth of cut (chip load) for a pass. Therefore, productivity is low.

2 Double Point Cutting Tool

A double-pointed cutting tool has two cutting edges that can cut and shear simultaneously in one motion. Single-point cutting tools contain one main cutting edge, while multi-point cutting tools contain more than two cutting edges for performing machining action in one pass.

In some cases, the only two categories into which cutters can be divided are double-point and multi-point. Additionally, a cutting edge is created by intersecting a rake surface and a flank surface. Consequently, double-point cutting tools have two flank surfaces and two rake surfaces.

The only example of a double-point cutting tool is a drill. Drills may have more than two flutes, but the typical metal-cutting drill only has two flutes. Drills’ modified cutting edges might also have more cutting edges, which would classify them as multi-point cutters.

Advantages of Double Point Cutting Tool

1. During machining operations, it absorbs shocks like vibrations.

2. It is capable of producing a fixed cutting element.

3. Unlike single-point cutting tools, this one has two cutting edges working simultaneously.

Disadvantages of Double Point Cutting Tool

1. The edges of this tool could be altered.

2. The issue with tool precision might arise.

3 Multi-Point Cutting Tool

A cutting tool with multiple points has more than two cutting edges that cut simultaneously during a pass. Cutting tools with more than one cutting edge is sometimes considered multi-point cutting tools (instead of double-point cutters).

In a multi-point cutter, the number of cutting edges can range from three to several hundred. As cutting edges appear at the intersection of rake and flank surfaces, rake and flank surfaces are also necessary for each cutting edge.

A popular example of this category is milling cutters. Other cutters are typically multi-point, except the fly milling cutter (a single-point cutter). For example, a small end mill might have three cutting edges, while a large heavy-duty cutter might have up to forty.

Advantages of Multi-Point Cutting Tool

1. It has a small chip load per tooth.

2. These types of cutting tools facilitate higher speed, feed, and depth of cut.

3. Multi-point tools have high material removal rate and productivity.

4. The tool wear is reduced.

5. It offers lower cutting temperatures and increased tool durability.

Disadvantages of Multi-point Cutting Tool

1. These tools are made with complex design and fabrication processes.

2. Multi-point cutting tools are more expensive than other types.

3. Inherently intermittent cutting.

Types of Cutting Tools

As their name suggests, cutting tools are used in machining processes to perform cutting operations. In many different machining applications, milling cutters can be used. Milling cutters were thus named after their respective roles in machining.

Following are the common types of cutting tools:

1. Single point turning tool

2. Drill

3. Milling cutters

4. Fly cutters

5. Shaper

6. Planer

7. Boring bar

8. Reamer

9. Broach

10. Hob

11. Grinding wheel

#2 Drill

A drill is a type of cutting tool that is employed to create circular holes or to drive fasteners. It is equipped with a bit, either a driverchuck or a drill bit. Due to their greater efficiency and usability, cordless battery-powered types are rapidly replacing hand-operated ones in terms of popularity.

These cutting tools are attached to drilling, milling, or lathe machines because they perform drilling operations. Various types of drills are used in woodworking, metalworking, construction, machine tool fabrication, and utility projects.

#4 Fly Cutter

Fly cutters are rotary tools used for plane surfacing that have one or more single-point tools. The fly cutter is a single-point cutting tool mounted in a special holder that resembles a lathe tool.

In order to machine large and flat surface areas, fly cutters are typically used on a milling machine. There is no need for additional arbors when using fly cutters in manual mills and machining centers.

#5 Shaper

Cutting tools in shapers are single-point tools with clearances, rakes, and other angles similar to those on lathes. Shaper tools are significantly more rigid and heavy to withstand the shock that the cutting tool experiences at the start of each cutting stroke.

For cast iron and steel, the side clearance angle in a shaper tool is only 2 and 40, respectively. The most typical material for a shaper tool is high-speed steel, but harder materials can also be machined using shock-resistant, cemented carbide-tipped tools. This tool is used on a shaping machine to give the workpiece a precise shape and accuracy.

#6 Planer

On a planer machine, only single-point cutting tools are employed. These tools are similar in shape and tool angles to those commonly found on lathes or shaper machines. However, these tools are heavier and have larger cross-sections.

In order to make heavy cuts over extended cutting strokes, planer tools must operate on coarse feeds. There are three different types of planner tools: solid, forge, and bit. The bits are constructed from cementite carbide, stellite, or high-speed steel.

#7 Boring Bar

Boring bars are commonly used in metalworking and woodworking. A common technique in construction is boring. For centuries, woodworkers have used boring as a type of drilling. Boring tools are used to make circular plunge cuts in woodworking.

Boring differs slightly in metalworking because the hole it creates doesn’t have to be circular. To create a perfectly circular hole, the tool is pushed and pulled up and down (on the Z axis) while plunging and dragging on the X and Y axes.

#8 Reamer

A reamer is a device used to enlarge or finish pre-drilled holes, holes that have been bored, or holes that have been cored to produce a good finish and precise dimensions. A reamer is a multi-toothed cutter used to remove relatively little material.

Reamer tools have cutting surfaces that are either straight, slightly twisted, or spirally fluted and are ground to a very precise diameter. Reamers can be divided into a number of categories based on their use, design, and shape. These types of cutting tools are used on the drilling machine to carry out reaming operations.

#9 Broach

A broaching tool has a series of distinct cutting edges along its length that is referred to as cutting teeth. By increasing the step between any two succeeding teeth on the broach, feed is accomplished. Broaches are typically made of high-speed steel (HSS). 

The linear movement of the tool with respect to the workpiece determines the broach’s cutting speed. The broach’s cutting edges’ contours determine the shape of the cut surface (machined surface). On the broaching machine, this cutting tool performs the broaching operation. 

#10 Hob

A hob is a cutting tool used for cutting teeth into a workpiece. It has helical cutting teeth and a cylindrical shape. In order to facilitate cutting and chip removal, these helical cutting teeth have grooves that run the entire length of the hob.

Additionally, there are special hobs made for unique gears like sprockets and spline gears. These types of cutting tools are used to perform hobbing operations on the hobbing machine.

#11 Grinding Wheel

The grinding wheel contains abrasive compounds for grinding and machining. The abrasive grains give the wheel its cutting ability, helping finish the material to the required dimensional accuracy and surface finish.

These wheels are employed in grinding machines. Grinding wheels are consumables, though their lifespan can range from a few hours to many years, depending on their use. As the wheel cuts, individual abrasive grains are periodically released, usually because they become dull and are pulled away by the increased drag.