Plasma cutting is a useful and adaptable technique that has very wide uses, like automobile, real estate, construction industry, and many other industries.

If you want to learn plasma cutting or you’re new to plasma cutting and want to improve your skills, this post is for you. In this post, I’ll go over everything you need to know to get started with plasma cutting.

Plasma cutting is a method of cutting metal with a particular machine known as a plasma cutter. It’s equipped with a special torch that emits a super hot and fast stream of gas known as plasma which can melt and cut through metal.

What Importance Does it Have?

I was to explain simply plasma machines are able to cut any type of metal e.g. aluminum, stainless steel, and cast iron.

Plasma-cutting machines can cut mild steel from thin sheet metal between 1/64 in. (4 mm) to 6 in. (150 mm) or more. which means that the plasma torch can do most of the cutting that you need in your welding shop.

I know there are a lot of other things that can be said about plasma cutting but I hope this is enough to give you a glimpse of how important and useful it can be when used correctly.

Scenarios When You Should Use Plasma Cutter

A plasma cutter can be the most appropriate tool to use in a variety of contexts. Below are a few examples that will give you an idea

1- When You Need to Cut Through Thick Materials: Plasma cutters are able to easily cut through materials that are up to 2 inches thick, which makes them a good choice for cutting objects that require a significant amount of force.

2- When You Require High Precision: Plasma cutters are a good choice for situations when you require high levels of accuracy, such as welding or fabrication and others. Because plasma cutters can produce cuts that are very precise which makes them a good choice for situations in which precision is important.

3- When You Need to Work in Speed: Plasma cutters can quickly cut through materials, making them a good choice when speed is important. Plasma cutters are easy to step and can give a speed boost as compared to other cutter types.

4- When Clear Edge Cut is Required: Plasma cutters produce a very clean cut with minimal burrs or other imperfections; this makes them ideal for use in situations where a clean cut is required. Thats why they are a good option for applications in which it is important to have a clean and finished edge.

Scenarios When You Shouldn’t Use Plasma Cutter

There are also circumstances in which a plasma cutter is not a good choice. Such as the following scenarios:

1- Don’t Use Them on Non-Conductive Materials: Plasma cutters are only effective on materials that are electrically conductive which makes them not suitable for cutting materials such as wood or plastic because they are only effective on electrically conductive materials.

2- Sometimes You Don’t Need High Precision Cuts: Plasma cutters are capable of producing precise cuts with a very clean edge. But in some cases, you might not want the edges to be very clean and clear. Although it is a very rare scenario still it should be kept in mind.

3- When Cost is an Issue: The cost of using plasma cutters can be high especially if you put them through a lot of work on a regular basis. This makes them not the most cost-efficient option for all cutting jobs.

Different Variations of Plasma Cutting

1. Duel gas plasma cutting
2. Water injected plasma cutting
3. Water shielding plasma cutting
4. Precision plasma cutting

1- Duel gas plasma cutting: This process uses two different gases, one for the plasma and one as an external shielding gas. The added shielding gas helps to protect the cut surface resulting in a cleaner cut that is free from oxides and nitrides.

2- Water injected plasma cutting: This process involves using a concentrated column of water surrounding the plasma column. The water column increases the swirl of the plasma stream resulting in a higher density and temperature for faster mechanized cutting.

3- Water shielding plasma cutting: In this process a large quantity of water is used to cool the torch and reduce the sound and reflected light. The water flow in this mechanized cutting process is higher than in the water injection process.

4- Precision plasma cutting: This mechanized process is used on thinner materials at slower cutting speeds in order to achieve very accurate cuts.

Plasma Cutter Components

1. Plasma Torch
2. Work Cable
3. Power Supply
4. Gas Cylinder
5. Cooling System (Water Circulator)

1- Plasma Torch: Plasma torch is the device that produces the plasma which is used to cut through the workpiece. It has a nozzle and an electrode. Through nozzle the plasma is emitted and electrode’s job is to create an electrical arc to ionize the gas.

2- Work Cable: A working cable is a flexible cord which is use to connect the power supply to the workpiece. It carries the electrical current from the power supply to the workpiece. It helps to generate the arc and ionize the gas.

3- Power Supply: Power supply’s job is to  provide the electrical energy needed to create the plasma and it also maintains the arc in the plasma torch. It typically consists of a transformer, rectifier and some setting knobs.

4- Gas Cylinder: The gas cylinder stores the compressed gas used to create the plasma in the plasma torch. Different types of gas may be used depending on the material being cut and the desired cutting performance.

5- Cooling System: Coolant system is used to prevent the plasma workstation from overheating. It includes water pump, reservoir, and hoses to circulate water through the system. Reservoir has a level indicator. Some systems even have a safety interlock to shut off the torch if the water level becomes too low.

Setting Up Your Plasma Cutter Machine

There are 5 things that you need to take into consideration when setting up your plasma cutting system

1. Material Type
2. Amperage
3. Voltage
4. Material Thickness
5. Cutting Speed

1- Material Type

Plasma Arc Cutting (PAC) works especially well on materials like carbon steel, stainless steel and aluminum that are up to a certain thickness.

These materials are good conductors of electricity which means electricity can flow through them easily In other words PAC works only works on materials that are conductors.

The PAC process can also be used to cut other types of metal like copper and nickel alloys but it might not be the most cost-effective way to do it. Sometimes you can still use the PAC process to cut thicker materials even if it’s not the most efficient way.

Also PAC process is good for cutting materials that have lots of different shapes like expanded metals or screens because it can start and stop cutting quickly without any problems.

2- Amperage

Compared to most other welding processes, the current (amperage flow) is much lower despite the higher voltage. Some PAC torches can run on as little as 10 amps of current flow.

A very large automated cutting machine may have a 1000 amp capacity, and powerful plasma cutting machines may have amperages as high as 200 amps. The faster and thicker they can cut, the higher the amperage capacity.

3- Voltage

DC high-voltage power source is necessary for the plasma’s creation.In contrast to the majority of welding processes which use voltages between 18 and 45 volts, plasma arc processes use voltages between 50 and 200 volts closed circuit and 150 to 400 volts open circuit.

Because the resistance of the gas increases as it is forced through a small orifice a higher electrical potential is necessary.

In order for electrons to flow through the circuit the potential voltage of the power source must be high enough to overcome the circuit’s resistance.

4- Material Thickness

Amperage, cutting speed and metal thickness are all related. The ability to cut thinner metal or at a slower rate depends on the amperage.

When cutting with plasma a fast travel speed will produce a much lower heat input than when cutting with oxyfuel.

The temperature of a steel plate that has undergone a plasma cut may only slightly rise after the cut.

Moments after a plasma cut it is frequently possible to pick up a part and discover that it is cool to the touch.

The same part would be much hotter and take longer to cool if it had been cut with oxyfuel.

5- Cutting Speed

I’ve provided the chart up top, which includes a list of different material types, thicknesses and suggested cutting speeds.

The maximum cutting speed for each material and thickness may also be listed in the charts. The recommended cutting speeds produce the best cuts but the higher speeds do not.

What is Kerf and Why Should You Care About It?

In plasma arc cutting (PAC) the kerf is the space left in the workpiece as the metal is removed during the cutting process.

The width of the kerf can be affected by several factors including:

1. Distance between the torch nozzle and the workpiece (Standoff Distance)
2. Diameter of the nozzle orifice
3. Power setting, the travel speed
4. Type of gas used
5. Condition of the electrode and nozzle tip
6. Swirling of the plasma gas

Narrower kerf is generally desired in PAC cutting because it leads to less waste and better utilization of material. However narrower kerf can also lead to increased bevel on the sides of the cut and greater dross formation.

To optimize the kerf width it is important to consider the specific requirements of a cutting project, such as the thickness of the metal and the desired level of precision.

It is also recommended to make test cuts to verify the kerf width before starting any large-scale production cuts.

In addition to affecting the kerf width, several of the factors that impact the kerf width also affect the bevel angle left on the sides of the plasma cuts.

The bevel angle can range from 1/28 to 38 degrees and is dependent on factors like metal thickness, torch speed, type of gas, standoff distance, nozzle tip condition and more.

Kerf is an important aspect to consider when performing PAC cutting as it affects the material usage and precision.

As I have mentioned earlier that different factors can affect the width of the kerf thats why it’s recommended to test the kerf width before starting.

Torch Standoff Distance in Plasma Cutter?

Torch standoff distance is the distance between the nozzle tip and the material being cut. Standoff distance is important for producing quality plasma arc cuts.

As the torch is raised the arc force is diminished and the plasma stream becomes less stiff. This causes the kerf angle (squareness of the cut) to increase.

Relation Between Kerf and StandOff Distance

Angular deflection and kerf angle are terms used to describe how square a cut is. The work side of the cut is nearly square at the proper standoff distance.

The kerf angle increases as the distance grows and the plasma stream starts to deform, and dross starts to build up on the bottom edge as the top edge starts to round.

The kerf angle starts to rapidly increase as the torch is raised higher above the metal surface. The bottom edge is developing more dross, and the top edge is becoming more rounded.

The cut will eventually stop going through the plate if the torch is raised any higher.

On some torches, it is possible to drag the nozzle along the surface of the material without damaging it. Some torches have a ring spacer that allows them to be drug, but this can cause the nozzle to become contaminated more quickly.

Right Method to Start the Plasma Cutting

There are several starting methods but the most common one is “high-frequency alternating current” carried through the conductor, electrode and then back from the nozzle tip.

It inolves following steps:

1- Gas Flow: The first step is to open the plasma gas solenoid which allows the gas to flow through the torch tip.

2- High-Frequency Generation: The high-frequency generator is turned on and the pilot arc relay contacts are closed. This ionizes the gas, creating an initial pilot arc between the electrode and the nozzle.

3- Establishing Pilot Arc: The torch is then moved closer to the workpiece, causing the pilot arc to jump the gap between the electrode and the workpiece.

4- Establishing Main Arc: Once the pilot arc jumps the gap, the plasma current relay inside the power supply closes and the main plasma arc is established.

5- Turn off Pilot Arc Generator: The pilot arc generator then turns off as the main plasma arc is established.

6- High-Frequency Current: High-frequency alternating current that is sent from the nozzle tip via the conductor, the electrode, and back starts the plasma cutting process.

Choosing the Right Gas for Plasma Cutting

Almost any gas or gas mixture can be used for the Plasma Arc Cutting (PAC) process. Changing the gas or gas mixture helps in controlling the plasma cut.

Although the type of gas or gases used will have a major effect on the cutting performance it is only one of a number of changes that a technician can make to help produce a quality cut.

Following are some of the effects that changing the PAC gas(es) will have on the cut:

1- Force: The amount of mechanical impact on the material being cut the density of the gas and its ability to disperse the molten metal.

2- Central concentration: The plasma stream will be more condensed in some gases. This element will have a significant impact on both cutting speed and kerf width.

3- Heat content: As the electrical resistance of a gas or gas mixture changes it will affect the heat content of the plasma it produces. The higher the resistance the higher will be the heat produced by the plasma.

4- Kerf width: The ability of the plasma to remain in a tightly compact stream will produce a deeper cut with less of a bevel on the sides.

5- Dross formation: It is possible to manage or get rid of any dross that may have accumulated along the bottom edge of the cut.

6- Top edge rounding: The rounding of the top edge of the plate can often be eliminated by correctly selecting the gas or gases that are to be used.

7- Metal type: Some metals might not be cut with a certain gas because the metal reacts to elements in the plasma, forming unfavourable compounds on the cut surface (es).

Table lists some of the popular gases and gas mixtures used for various PAC metals. The choice of a gas or gas mixture for a particular operation must be tested using the setup and equipment being used in order to maximise system performance.

With constant developments and improvements in the PAC system, new gases and gas mixtures are continuously being added to the list.

It is crucial to have the proper gas flow rate for the tip size, metal type, and thickness in addition to the gas type.

Too low of a gas flow will result in a cut having excessive dross and sharply beveled sides as you can see in the image above.

Due to waste gas and plasma stream turbulence, a high gas flow will result in a poor cut. For more precise adjustments, the flow at the plasma torch can be tested using a flow measuring kit.

How to Setup Plasma Cutting Machine?

Wearing all of the required personal protective equipment and following all of the manufacturer’s safety rules is crucial before setting up a plasma cutting machine.

Take following steps to step your equipment before starting cutting

Step 1- Adjustments to the electrode tip, nozzle tip, nozzle or other torch components should be made before turning on the machine power. Because the user could be shocked if the gun trigger is accidentally activated while servicing these parts

CAUTION: The open circuit voltage on a plasma machine can be high enough to cause severe electrical shock or death

Step 2- Make sure the work clamp is connected to a clean and unpainted spot on the metal that will be cut

Step 3- Check for anything behind the cut that could block the sparks from falling free of the cut. Also anything that could be damaged or set on fire with the sparks

Step 4- Set the cutting amperage to maximum and make a test cut to see if the material can be cut cleanly or not

Step 5- Reduce the amperage and make another practice cut. Repeat this procedure until you can make a clean cut with the amperage set as low as possible. The life of the torch’s components will be prolonged by lowering the amperage as much as possible.

How to Properly Take Care of Your Plasma Cutter

• Make sure to keep the machine clean of dust and debris
• Make sure to keep the air filter clean and replace it when necessary
• Clean the nozzles and electrodes regularly. Replace it when it is damaged
• Use the recommended lubricant for the machine’s moving parts
• Keep the connections tight. regularly check for loose connections and tighten them
• Inspect the hoses for leaks or damages. replace them if they are out of shape
• Keep the machine in a dry and clean environment

Common Problems with Plasma Cutters and Troubleshooting

Problem	Troubleshooting Steps
Cut quality is poor	1. Check the air pressure and flow.  2. Check the consumables, nozzles and electrodes may be worn.  3. Check the cut parameters, amperage may be set too high.
Machine won’t start or cuts out	1. Check the air pressure, flow and filter.  2. Check for any loose connections.  3. Check the electrical circuit and fuses.
Arc is unstable	1. Check the air pressure and flow.  2. Check the consumables, nozzles and electrodes may be worn.  3. Check the cut parameters, amperage may be set too high.  4. Check for any external interference.
Machine makes unusual noises	1. Check for loose parts.  2. Check for any obstructions.  3. Check for any wear on moving parts.

Safety Concerns in Plasma Arc Cutting (PAC)

The majority of other electric welding and cutting procedures have many of the same safety problems as PAC. This technique raises certain unique problems. some of these problems are stated below:

1- Electrical shock: Extra care must be used since this procedure has a significantly greater open circuit voltage than any other does.

This welding equipment has a far larger potential for deadly shocks than any other welding equipment.

2- Moisture: With PAC torches, water is frequently used to cool the torches, improve the cutting quality, or create a water table.

When using water, it’s crucial that there be no spills or leaks. Moisture on the floor, wires, or equipment dramatically increases the risk of electrical shock.

3- Noise: Noise is created as a result of the plasma stream’s rapid passage through the nozzle opening. As the power level rises, so does the sound level.

The decibel (dB) level is beyond acceptable limits even with low-power equipment. To protect the operator and those around from harm while the PAC equipment is in use, some kind of ear protection is necessary.

The cumulative effects of loud noise might damage one’s hearing. If necessary measures are not taken, one’s hearing will deteriorate over time.

4- Light: Light radiation in all three spectrums is produced by the PAC process. If the eyes are not shielded from this intense visible light, night blindness will result. Ultraviolet light is the most hazardous kind of light.

This light may burn the skin and eyes, much like other arc processes. Infrared, the third light, provides a heat-like sensation and is less dangerous. While any PAC is running, eye protection of some kind must be used.

5- Fumes: This technique generates a significant amount of potentially dangerous fumes. They should be removed from the workspace using a specified procedure.

For manual labour, a downdraft table is perfect, but bigger applications could call for some specialised equipment. Fumes may be considerably reduced by using a water table or a water shroud nozzle.

6- Gases: Hydrogen is a flammable gas that is included in certain plasma gas mixes; as a result, additional care must be taken to ensure that the system is leak-proof.

7- Sparks: There is always a risk of an unintentional fire when a procedure generates sparks. This is more of an issue with PAC since the operator’s eyesight is limited by the welding helmet and the sparks are often flung some distance from the work area.

A fire watch must be present if there is even a remote chance that sparks may fly out of the immediate work area.

Conclusion

Plasma cutting is a versatile and powerful tool that can be used in a variety of industries.

There is always more to learn and improve on whether you are new to plasma cutting or an experienced welder.

We hope that this post has provided you with useful information and techniques to help you get started with or improve your plasma-cutting skills.

When using a plasma cutter remember to always take proper safety precautions and practice and hone your skills.

You can become a pro at plasma cutting in no time if you have the right knowledge and practice.