Metal Cutting Process: Definition, Types & Applications

Metal cutting processes are the central pillars of raw material processing. Every manufacturing industry uses metal materials or tools. Therefore, metal cutting processes power the entire manufacturing sector directly or indirectly.

There are countless applications of metal cutting processes, each with specific requirements. Therefore, many different types of metal cutting processes have emerged in the industry.

This article will discuss the various metal cutting methods and how to choose one for your requirement.

What is Metal Cutting?

Metal cutting is a subtractive metalworking process of dividing a metal workpiece into multiple parts using force or other erosion techniques. The cutting action can be generated with blades or methods like electrical discharges and water jets.

Who Invented Metal Cutting Processes?

Henry Maudslay is the inventor of metal cutting processes like the lathe. The actual history of metal working dates far back to ancient times like the Egyptian Civilisation. The Late Medieval age saw the emergence of metal punching machines. With the development of electrical components, the metal cutting methods shifted to electrical operations instead of physical. The later development of CNC technology further automated the process.

What are the Uses of Metal Cutting?

Metal cutting is among the most common processes for raw material processing. Metal cutting processes shape raw sheet metal like mild steel for further manufacturing techniques. Advanced metal cutting techniques like waterjet cutting can directly create the final part from raw metal sheets and blocks.

Different Types of Metal Cutting Methods

There are many different types of metal cutting processes. Some of these types are:

Mechanical Cutting

Mechanical cutting methods remove the material by using a sharp cutting tool against the metal. There are mainly four mechanical cutting processes for metals:

Turning

Turning is usually done on cylindrical metal bars and rods with a non-rotary cutting tool. This process is used for making external cuts on the metal. If turning is done from the inside, the process is called boring.

Advantages

Fast cutting speeds
Good accuracy
Less lead time
Works on all kinds of metals and alloys
Doesn’t require highly skilled operator

Disadvantages

Works on only circular parts
Costly equipment
Frequent tool wear
Large amount of removed material
High heat generation

Uses

Engine parts
Shafts
Holes
Grooves
Threads
Tapers

Milling

Milling uses a rotary cutting tool to remove material from a stationary workpiece. It can use many different types of tools to achieve the desired result.

Advantages

High accuracy
Faster cutting process
Versatile in material application

Disadvantages

Large amount of excess material
Requires skilled operator

Uses

Cutting profiles
Surface contours
Die cutting
Dental Equipment
Defense parts

Drilling

Drilling is a common metal working process for cutting small diameter holes in metal. It works for metal sheets, blocks, and complex finished parts.

Advantages

High accuracy
Best option for cutting small diameter holes
Works on all material

Disadvantages

Heat generation
Limited application besides hole cutting
High tool wear

Uses

Holes for secondary assembly of parts
Screw cavities
Aesthetic application

Sawing

Sawing is more common for wood-based materials but also works for metals. Sawing uses a toothed cutting tool for slicing through the material.

Advantages

Disadvantages

High heat generation
Faster tool wear
High kerf losses
Doesn’t work well for hard metals
Limited to straight line cuts

Uses

Pipe cutting
Tube Cutting
Sheet metal cutting for small projects

Shearing

Shearing accomplishes the cutting process with the action of blade on either side of the metal sheet. Shearing tools come in many different configurations. Bench shearing is one of the most common shearing techniques for metal cutting.

Advantages

Low cost
Simple setup
No requirement for highly skilled operator
No temperature rise

Disadvantages

Low precision
Only limited to straight cuts
High tool wear
Low safety

Uses

Fast processing of high volume of sheet metal

Punching

Punching uses the physical force of a press to cut out the required shape from the metal. Dies support the metal, and the press is in the shape of the needed cutout.

Advantages

Simple cutting process

Cheap
No need for a highly skilled operator

Disadvantages

A lot of material wastage
Poor accuracy

Uses

Cutting basic geometric shapes

Abrasive Cutting

Abrasive cutting processes work by the removal of metal particles. The primary factor here is friction instead of force or sharp edges of the cutting tool.

Waterjet Cutting

Waterjet cutting is one of the best metal cutting techniques out there. Waterjet cutting technique uses the force of highly pressurized water for metal particle erosion. It is a cold cutting process that doesn’t require physical contact of the waterjet cutting head with the workpiece. Waterjet cutting can make linear, non-linear, and internal cuts in a workpiece.

Advantages

High precision
No heat effects
Minimal material wastage
Fast speed
High Safety
Waterjet cutting can cut thick materials
Works for all metals and non metals
Superior edge quality

Disadvantages

Waterjet cutting requires skilled operator

Uses

Surgical equipment
Raw material processing
Metal fabrication workshops
Automotive sector
Defense equipment
Aerospace industry

Grinding

Grinding uses abrasive wheels to remove minimal material from the workpiece. It is generally applied in the secondary finishing processes for metals. The material removed by this process is minimal. However, it does not have any significant cutting capabilities.

Advantages

It can achieve good surface finishing
Less material removal
Good for turning workpiece into precise dimensions

Disadvantages

Limited capabilities
Works only for smoothening surfaces and edges

Uses

Any secondary finishing application

Thermal Cutting

Thermal cutting processes cut metals by melting the material from the required location. Thermal cutting processes have good precision. However, they create heat-affected zones that can ruin the integrity of the workpiece material.

The various thermal cutting processes are:

Laser Cutting

The laser-cutting process uses high-frequency light rays to melt the workpiece. Laser cutting is one of the most precise methods due to the high narrow nature of the laser beam. The laser cutting process is not limited to linear cuts. However, laser cutting cannot create multi-axis cuts.

Advantages

Laser cutting works on every material
High precision
Laser cutting can cut complex shapes

Disadvantages

Heat affected zones
Laser cutting has severe limitations on material thickness
Generation of dross due to oxidation of melted metals

Uses

Automotive body parts
Engines
Panels
Smartphone bodies

Plasma Cutting

Plasma cutting utilizes an ionized stream of gases to melt the metal for cutting. Once the metal melts, a high pressure air flow blows away the melted material. The ionized jet has a very narrow width, resulting in a high precision cut. An important thing to note is that this method works only on electrically conductive materials. Therefore, any non-conductive metal alloys cannot be cut by plasma cutting.

Advantages

Plasma cutting is good for materials like stainless steel
Low cost of consumables
High precision

Disadvantages

Formation of heat-affected zones
It doesn’t work for thicker materials
Release of toxic fumes
Generates arc glare

Uses

Metal fabrication
Salvage Yards
Construction projects
Architecture

Oxy-fuel Cutting

Oxy-fuel cutting is also known as flame cutting. It uses a flammable fuel mixture of oxygen with other gases to generate high temperatures. The high temperatures melt the material, leading to the cutting action.

Advantages

It is a very portable cutting method
There is no requirement of electricity
It is a cheap and simple process

Disadvantages

It has a very poor accuracy
There is the emission of toxic fumes
Poor safety
It doesn’t work for thicker materials

Uses

Small-scale metal fabrication workshops

Electrical Discharge Machining (EDM)

Electrical discharge machining works by melting metal through electric arcs. An electrode is brought close to the workpiece without making physical contact. The workpiece is turned into another electrode. On the voltage application, there is an electrical discharge between the two electrodes. These discharges raise the temperature and melts the material.

Advantages

Ability to create non-linear cuts

High precision

Works with hard materials

Disadvantages

Extremely high power consumption
Slow cutting speed
Only works for conductive materials
Formation of heat affected zones

Uses

Manufacturing operations of molds and dies
Making metal tools

Electrochemical Machining

Electrochemical machining combines the use of electricity with chemical reactions to remove the workpiece material. It follows the reverse mechanism of electroplating. It can produce metal parts quite quickly.

Advantages

Works well with high hardness metals
It doesn’t create heat affected zones
There is no tool wear
Fast speed

Disadvantages

Costly metal cutting process
Probability of metal corrosion
Only suitable for conductive materials

Uses

Cutting hard materials
Working on small-scale parts where other methods don’t apply
Working on complex, non-planar shapes

What is the Most Common Way to Cut Metal?

Drilling is the most common metal cutting process. It is used in conjunction with every other metalworking processes for cutting holes. Milling is most common among industrial applications that involve slicing metal pieces into multiple segments. However, techniques like waterjet cutting and laser cutting are gaining preference due to their benefits.

What is the fastest metal cutting process?

Laser cutting is the fastest metal cutting process. A 1000 W laser can cut 3mm thick carbon steel at the speed of around 3 meters per minute. The exact speed of any metal cutting process depends on the type and dimension of the workpiece.

What is the most accurate metal cutting process?

Waterjet cutting is the most precise cutting method with a tolerance of +/- 0.001″. Laser cutting can also provide similar accuracy to this value. However, laser cutting creates heat-affected zones which reduce its accuracy to some extent.

How to Choose a Metal Cutting Technique?

There are numerous metal cutting methods available for industry professionals. Choosing the right method should be done after evaluating multiple factors. The response to these factors can vary based on the particular project. These factors are:

Type of Material
Material Thickness
Required Precision
Production Volume
Cost
Finishing Requirements
Cutting Tool Wear
Environmental Impact
Operator Skill Requirement
Workshop Space Availability
Safety
Material Wastage

Endnotes

A good metal cutting machine can be the difference between a heap of rejected parts and a good quality outcome.

Waterjet cutting machines by Techni Waterjet has completely changed the landscape of metal processing. These machines can handle any thickness and even create finished metal parts without secondary processing. Techni Waterjet might be something to consider if you are looking for a metal cutting machine.

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