Cutting Tools for Metals – Definition, Types, Materials, Defects


Hey readers! Do you know what are cutting tools for metals? In this article, we will learn all about cutting tool including definition, types, characteristics, defects, etc.

Let’s explore!

What are Cutting Tools? Definition

Cutting Tools Basics

While inventing different things, humankind found some of the processes quite important. After the invention of Fire and wheels, one of the prominent ones is cutting. Right from the ages, the need for cutting is quite evident. In every aspect of life, cutting keeps an adequate place. In modern times this has been given machining, though machining is somehow different from cutting. The main differentiating factor is the movement.

We use various kinds of cutting tools, and it is quite efficient to get a grab of these as it is among the main methods. Here we have to understand some of the aspects of machining that can help understand the concept of cutting tools.

Machining is one of the machining operations through which the process of shearing is gradually removing excess material. A wedge-shaped, hard, and rigid tool is used, which is known as the cutting tool. The core function of this is to provide compression to the work or job material, hence shearing or carving out the excess layer.

cutting tools metals definition types materials defects
Cutting tools metals definition types materials defects

This article will help us get a deep understanding of the cutting tools by emphasizing different aspects. Numerous other parameters are being discussed here, along with the core introduction, example, features, materials, and classification. We will try to provide holistic knowledge about cutting tools. Let’s start with the proper introduction of the cutting tools.

Definition of Cutting Tool

Cutting tools are equipment that is sharp-edged and wedge-shaped. These are used for removing the excess layer of the materials. The shearing force removes the excess layer of the workpiece. We can attain desired size, shape, and precision while using these cutting tools.

  • Cutting tools are mounted on the machine tools, and it comes into motion with a relative velocity between the cutting tool and workpiece.
  • There are different kinds of arrangements for the cutting action by calibrating the machine tool and the attached cutting tools.

Purpose of Cutting Tools

Let’s see the purpose of cutting tools,

  • The core purpose of cutting tools is to provide a force to a specific layer of the workpiece while applying a shear force.
  • For this, the cutting tool should have a wedge-shaped structure with a sharp edge, as it provides smooth and easy removal of excess material with minimum power.
  • Along with these, the cutting tool materials should be of appropriate hardness that can cope with the maximum contact during machining.

What are the Commonly Used Cutting Tool Types?

There are some of the commonly used cutting tools that are pretty popular. They are being used for different machining purposes. 

The following are some of the best-known cutting tools that are used widely:

  • Drill: These are the bits that are used for drilling operations in a drilling machine.
  • Milling cutter: The common of all types which are used for milling operation in milling machine
  • Single point turning tool: These are the cutter which is used for turning operation. It is specifically used in the lathe.
  • Fly cutter: These are the cutter for fly milling operation, which is used in milling machines.
  • Reamer: These are the cutter which is used in drilling machine specifically used for reaming operation.
  • Hob: With this, we can easily perform the hobbing operation in any of the hobbing machines
  • Boring bars: These are used for boring operations, which can be used in boring or drilling machines.
  • Planer: Specifically used for planning operation used in planning machine
  • Shaper: These are the cutter for shaping operation which is used in shaping machines.
  • Grinding wheel: These are the most common of all, known as abrasive cutters, and are specifically used for grinding operation in grinding machines.

Prime Attributes of Cutting Tools

The cutting tools have numerous properties which help to attain quality-oriented cutting and ultimately provide accurate products. The following are the prime attributes that can help us to understand the core properties of cutting tools.

  • Toughness

The cutting tools should be equipped with proper toughness while cutting the chipping, or fracture is common. If the cutting is not aptly toughened, it can get fractures and ultimately don’t provide accurate cutting operation.

  • Hardness

The strength of the cutting tools matters a lot. This is one of the attributes that should be maintained to get optimal cutting.

  • Resistance against wear

Resistance against getting worn up or wear resistance is critically an attribute of cutting tools that provides long-lasting operation. It also provides a tool for an extended life, which is quite efficient.

These are some of the core attributes that make any cutting tool quite efficient. While understanding this aspect, we also need to get an idea of those parameters that help in making the whole cutting process efficient.

Prominent parameters that make cutting effective

The following are some of the core parameters that make cutting effective. Every machining operation should consider these as it provides efficiency and help us make the process cost-effective. We can also increase the efficiency of the machining by considering these parameters.

Movement of the cutting tool

The core meaning of cutting is to cut off parts from the designated workpiece using a specific tool. The movement of this is defined by two aspects that re-cutting and feeding. These are the prominent ones for machining. The cutting action is effectively achieved by a cutting tool with a motion specifically in a straight line.

The feeding has explicitly the movement that cuts the different parts by moving the cutting tool. Before cutting on one line, the cutting tool perpendicularly provides in the cutting direction. While repeating this motion, we can create a plane.

Deflection

Deflection is one of the parameters that should be catered to effectively. While machining, the workspace and tool come into direct contact, and their forces comply with each other, which may generate deflection. The generated deflection can be numerous kinds which may vary according to the use of the cutting tool.

For instance, while using a cutting tool, the deflection effectively depends on different factors such as the type of cutting tool used, the area of the cut. The area of the cut end affects the deflection, which should be considered while machining.

While machining, it is quite essential to keep the deflection in mind as it can quickly help maintain the efficiency, durability, and quality of the tools used.

Speed

Speed is one of the key parameters that are quite efficient for cutting tools. Increasing work efficiency with effective quality control helps a lot.

However, while increasing the speed, we can achieve working efficiency, but it should be attained with proper and additional planning as it increases the risk of thermal deformation and deflection. If there is a substantial increase in the machining speed, it may shorten the cutting tool’s life.

This can easily reduce the life of cutting tools and also increase the overall cost associated.  There are some of the backdrops of this parameter, as by increasing the speed, we can lose the accuracy and precision. In addition to these, the overall life also depletes when we increase the speed.

Temperature

This is one of the parameters that affect a lot. While cutting or machining, the contact between the tool and workpiece generates heat. This causes a change in the temperature of the workpiece. The temperature rises explicitly. With the increase in temperature, it is possible that we can lose machining precision as well as accuracy. The durability of the cutting tool also gets seriously affected.

The most prominent area that comes into the limelight is the cutting region. The temperature is directly proportional to the machining speed. When the machining speed increases simultaneously, more heat is being generated. It is recommended to keep an account of rising temperature while machining.

This saves us from additional cost as well as provides long-lasting usage. We use cutting oil which acts as a lubricant and cools down the increasing temperature of the cutting tool. The oil specifically reduces the friction between tool and workpiece, thus rinsing away the chips. Most of the time, the water-soluble type of cutting oil is preferred to cater to the temperature.

Types of Cutting Tools Based on Material

It is pretty important to get an idea about different kinds of cutting tools. Here we are providing some of the types of cutting tools and their properties. With this excerpt, we will formulate an idea that brings us more closely to understand the cutting tools. These are more of the materials used for the manufacturing of different kinds of cutting tools.

Carbon tool steel

This is one of the prime kinds of cutting low-cost tools. The basic carbon tool steel cutting tool is equipped with 0.5-1.5% of carbon.

Applications

Carbon tool steel is used for low-speed machining. Carbon steel tool is equipped with the fundamental property that provides optimal machinability. These are abrasive resistant and can be seen where there is a need to maintain the sharp cutting edge to get good machinability.

These are used in milling tools, forming and turning tools. These kinds of cutting tools are used for soft materials such as aluminum, brass, and magnesium.

Limitations

The cutting tool made up of this material loses its hardness at a temperature above 200 degrees Celsius. The use of this material is not for the high-temperature zone.

Modern machining operation doesn’t use cutting tools that are made up of carbon tool steel.

High-speed steel (HSS)

High-speed steel is the high-carbon steel that is prominently equipped with alloying materials such as chromium, tungsten, molybdenum. It effectively improves the toughness, hardenability, and wear resistance.

Applications

It is used explicitly for that machining operation where there is a need for a high metal removal rate.

Limitations

The cutting tools made up of this material lose their hardness at 600 degrees Celsius. For this, it credibly needs coolant, which increases the tool life. We can use these by re-sharpening.

Diamond

Though this is a material that is quite expensive, it is known to be the hardest material that is being used for cutting. It is equipped with a high level of thermal conductivity as well as a melting point.

It has a low friction coefficient, par level abrasion resistance, and minimal thermal expansion.

Applications

It is used at those places where there is a need for machining for hard materials such as nitrides, glass, and carbides. They provide optimal surface finish as well as specifications accuracy.

Limitations

These are not cost-effective and also not for machining steel.

These are a few other materials used for cutting tools, as follows:

  • Cobalt
  • Ceramic
  • Cemented Carbide

Types of Cutting Tools Based on Cutting

Based on operation, cutting tools are two types.

Orthogonal Cutting tool

  • The direction of cutting tool and cutting edge is perpendicular.

Oblique Cutting tool

  • The direction of cutting tool and cutting edge is any angle other than perpendicular.

Types of Cutting Tools Based on Operation

Milling Tool

This type of cutting tool is used mainly to cut the slots, gears, etc.

Turning Tool

As the name suggests, it is used for turning operation, it is mainly used lathe machine.

Drilling Tool

As the name suggests, it is used for drilling operations, it can be seen in lathe machines.

Thread Cutting Tool

As the name suggests, it is used for tread cutting, which can be seen in lathe machines.

Type of Cutting Tools Based on Nos of Cutting Edges

There are three different types of cutting tools based on the cutting edges,

Single-Point cutting tool

  • There is a single edge only.
  • It helps to make many operations like making flat surface, turning, facing, etc.
  • You can see single point cutting tool in shaper machines, lathe machines, etc.

Double-Point cutting tool

  • There are two edges in this cutting tool.  
  • Two cutting edges are working simultaneously.
  • Due to two edges are working, it is balanced.
  • Less vibration,
  • Stable operation

Multi-point cutting tool

  • There are more than two edges in this cutting tool.  
  • Sometimes, it doesn’t have any cutting edges.
  • Drilling tool can be multi point cutting tool in addition to double point cutting tool.

Attributes to look for while choosing cutting tools

After getting all the ideas about the types of materials and probable defects, choosing an efficient cutting tool is quite essential. Cutting tools play a vital role while defining the whole work process for machining. It is prominent to choose some of the practical alloys that provide a par level of accuracy.

The proper selection of cutting tools can give optimal results. These parameters include grade, geometries, and a whole lot of properties. With this, we can quickly improve productivity in the machining process.

The different parameters included while choosing cutting tools are fixture stability, overall machine dynamics, and power available. These combinations provide optimal results in machining.

Apart from this, it is pretty important to define a strategy that can effectively cut or machine. Apart from choosing conventional ways of machining, some prominent factors maintain efficiency. For example, we have to keep the average chip thickness ratio with proper cutting speeds and feed rate according to the radial engagement of the tool.

Defects in Cutting Tools

While understanding the core of cutting tools, it is quite important to get an overview of some defects that can cause massive problems in machining.

The following are some of the defects that should be catered to get accuracy, precision, and elongated tool life.

Cutting Tools Defect: Tool failure

Defects

While cutting or machining operation, the foremost defect that can come is the tool failure. We also know this as premature tool failure or tool cutoff. Whenever tool chips or breaks below its rake face, it can create numerous defects in the product, increasing the inefficiency.

If this happens, we can easily lose machine time, energy costs, labor hours, and expensive raw materials, which are quite difficult for any machining shop. For this, we need to have cleared our goals while machining.

It is quite important to maximize the amount of work your tool can achieve.

Solution

The foremost solution for this defect to be catered to is consulting a machinability study that helps get an idea about what is causing the tools to wear or break down faster than their expected life. The results can be used to avoid the problem gradually. Apart from this, it is quite important to monitor daily.

Determine the power factor and ensure to correlate it with premature tool failure. It can easily reduce the probability of tool failure.

We can also keep a check on other factors and correlate them to failures, such as vibrations at the tool site, temperature, acoustic output, and several others. With this, we can easily detect and prevent any supposed changes during the machining operations.

Cutting Tools Defect: Chattering

Defects

In machining or cutting operations, the problem of chattering is common. We cannot expect zero chatterings as it is among the foremost ones. Every tool holding system is equipped with a cutting tool and tool holder. These are amongst the most flexible bodies of a machine.

During the normal course of operation, they resonate, and ultimately the problem of chattering comes. The probable factor that affects the chatter rates is the toughness and stiffness of the workpiece. It also occurs due to overhanging in the spindle, cutting parameters used, and several teeth in the tool.

These are specifically wave-like structure that effectively reduces the quality of output. The variable load can also cause chatter waves. It also increases wear on the edge of products.

Solution

The solution for chattering is to conduct a tap test. In this, the accelerometer is connected to the cutting tool end, and then the cutting tool is struck with an instrumented hammer that also contains an accelerometer. The data plots the ranges in speed which the tool is not prone to cause chattering.

In this, the limiting factor for chattering can be the metal removal rate. If we increase the metal removal rate, then the probability of chattering increases substantially.

Cutting Tools Defect: Coolant or cutting fluid issues

Defects

Many machining shops and industrial setups are equipped with those setups, which include different tool setups. These tool setups need to cool down; the increasing temperature can reduce the life of the cutting tool.

Apart from this, numerous other issues such as pH shifting and polarity shifting between the residual fluid and coolant fluid cause inefficiency.

This should be checked at designated intervals as it can easily harm the product and makes them prone to attain corrosion.

Here one of the most prone defects that can occur is chemical foaming, which reduces the efficiency of the cutting fluid which can easily lead to tool failure and wear.

Solution

We can conduct a cast-iron chip test, which shows the amount of cutting fluid provided. There are different kinds of fluids that help in cooling the tool. There are different grades of lubricant and cutting fluid that can help in cooling down and ultimately helps in increasing efficiency.

Cutting Tools Defect: Downtime

This is amongst the most common of all defects that persist in any process. While machining or cutting, there can be issues that increase in throughput time. There are numerous reasons for this, such as job defects, low RPM. These act as a limiting factor for production. 

Sometimes the downtime is also caused due to subsidiary works such as cleaning machines, changing fluids, tools, and different production runs.

For this, we now have some of the innovative ways that decrease the downtime issues. IoT is among the foremost solutions for this.

Solution

To cater to this defect, it is recommended to connect your machines. It is one of the affordable and easier ways to cater the downtime issues. We can opt for somehow the software or computer-oriented software to check any loss. These can easily show the areas where there are hidden inefficiencies and the probable areas that need rectification. 

Cutting Tools Defect: Human adequacy and accuracy

In most machining operations, the need for human intervention is quite prominent. However, nowadays, automation has its fair share of popularity, but we need human intervention in innovating, maintenance, and problem-solving. Apart from these, they are also useful for process optimization.

In any process, they also have their limitations which can impact productivity. In machining, it is quite probable. Sometimes, an operator can face difficulties in loading or lifting stock onto a machine end, decreasing the overall throughput.

Solution

For solving this problem, machine data is of utmost importance. Apart from that, digital connectivity can easily help in identifying human-based errors or inefficacies. A positive approach and continuous monitoring can help to reduce this kind of error in machining or cutting.

With these defects understanding it is quite easy to get a holistic idea and taking action. These are some of the commonly caused defects that can decrease efficiency and deteriorate the end product. To cater to these, there are effective solutions that should be considered.

With these, we can easily cater to all the problems associated with machining or cutting defects. These defects and their measures to correct help us to be proactive in getting all the products.

How to take proper care of cutting tools?

While using cutting tools rigorously and continuously, it is quite essential to keep some of the core things. These will help us get proper machining and make it quite efficient for longer usage. The following are the attributes that should be considered while taking adequate care for cutting tools:

Controlling the heat

This is one of the factors that substantially affect the life of cutting tools. There is a massive generation of heat when two metal objects come into contact with each other. This heat is quite lethal and due to this metal surface and tips of the cutting tools get wear out.

It is quite necessary to use oil or lubricants, or coolant while cutting. It helps in attaining elongation in the overall life of the tools. The lubricant, coolants, or oil are anti-friction agents that control the friction between different objects, thus preventing them from getting wear out.

Controlling the chipping factor and edge preparation

While using cutting tools for machining, edge preparation and chipping are quite efficient. In this, the material gets removed from the sides of the cutting tool. This is effective in extending the life of the cutting tool in different ways.

It strengthens the edge of the tool by gradually dispensing the segment portion from the metal. With this, we can also prevent the tool from chipping. With this, we can easily balance the toughness and hardness of the cutting tools.

Keeping a check on tool configuration

While using the cutting tools, it is quite essential to design the tool to be capable of a higher metal removal rate. The tool configuration provides effective control that makes the tool adaptable to work on different spindle applications.

Apart from these, the tool should be apt enough to withstand any additional stress that comes into play when there is repeated motion and the load.

Protective coating of the inserts

When it comes to specific kinds of cutting tools, then inserts are pretty popular. On these inserts, it is quite essential to check the coating applied. This protective coating should be considered based on the design and nature of the tool. This coating is capable of preventing the devices from excessive heating.

As per the usage, there are mainly two kinds of the layer that are pretty popular, Physical Vapor Deposition and Chemical Vapor Deposition. In this, PVD is relatively thinner than CDV. PVD is mainly used for sharp-edged tools.

Conclusion

With the holistic knowledge about the cutting tools, it is now apt for us to get all the information crystal clear. This article will help you in the best possible ways. The process of machining can be effectively simple with comprehensive information as mentioned above. The detailed introduction of the cutting tools with their kinds is reasonably practical.

In addition to that, the proper usage and factors while choosing cutting tools can help in the best possible ways. However, if we want to understand in-depth the cutting tools, then that will need elaborative analysis.  With this article, it is quite easy to be equipped with all the relevant information, making cutting tools an insightful topic.

Any questions, please let us know!

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