plasma torches of cutting machine close up in mechanical shop

How Can I Make Clean Plasma Cuts?

No one likes fighting with their tools. A well-maintained plasma cutting system should run like a dream. However, sometimes it just seems difficult to get a clean cut. To avoid these complications, let’s go over the necessities for making clean plasma cuts.

Making clean plasma cuts requires several conditions to be met. These conditions needed for making clean plasma cuts are:

  1. Cut at an appropriate velocity for the thickness of the material.
  2. Use the correct air pressure.
  3. Adjust the amperage for the thickness of the materials.
  4. Replace worn consumables as required.
  5. Firmly secure the project.
  6. Ensuring you have a properly connected circuit.
  7. Utilize filtered, clean air.
  8. Maintain a correct standoff distance.

Let’s go over all of these steps, as well as a few others, to make sure that you’re getting the most out of your equipment.

Cutting Speed for Plasma Cutters

If you don’t cut fast enough, you’ll end up with an ugly cut. Some materials, like aluminum, are especially sensitive to speed.

How can you tell if you’re moving at the right speed for your plasma cutter?

To cut at the correct speed for a plasma cutter, watch the sparks. If the sparks are coming down straight under the workpiece, you’re cutting too slow. If the sparks are spraying above the workpiece, you’re cutting too quickly. Your sparks should come down at an angle of 20 degrees beneath the cut.

If you’re using a machine that can easily handle the thickness of metal you’re working with, you should be able to nearly eliminate the slag at the bottom of the cut by increasing your cutting speed. Ultimately, though, the more consistent your speed is, the nicer the piece will look.

Some guys find that, for hand-held machines, it’s easier to keep the torch speed constant and steady when they’re pulling in instead of pushing the torch out. Either way, make sure you trace the motions before starting to get a feel for a good position.

If you’re cutting thick material, crank the power on your machine to the max and adjust your travel speed to maintain good cutting conditions. For thin material, keep the amperage low and swap out for a low-amperage tip. It will keep your kerf clean and tight.

Consider using a hand-held unit to do something precise or repetitive; consider using a guide. You can buy straight and circle guides that are very easy to use. For more complex shapes, you can make yourself a pattern. It will allow you to focus more on maintaining a good speed instead of trying to make the right shape.

Setting Appropriate Air Pressure

There may be more than one place where you need to adjust air pressure, depending on what type of equipment you are using. Some plasma cutting machines have a built-in air compressor, so you wouldn’t have to worry about it. Some machines have automatic air pressure control features that automatically changes the air pressure according to the amperage settings. And some machines have neither of these features and therefore, they require that you set things up appropriately.

Due to the variety of plasma cutting machines on the market, you should check your user manual to ensure that you are setting things up appropriately for the equipment you are using. For example, some plasma cutters have an intake valve where you hook up a compressed airline with a maximum pressure rating. Exceeding that pressure rating could cause damage or injury, so you need to check that user manual.

Correctly Adjusting The Amperage

Adjust your amperage setting according to the user manual’s recommended settings for the particular plasma cutter you are using. But, there’s more than just adjusting the amperage. 

One thing that you’ll want to make sure of is that you’re using the right tip for the amperage setting. You should have at least one tip for high amperage and one tip for low amperage. Running the wrong tip for the set amperage will lead to premature wear. That means that you’ll need to either fork up some cash or suffer the shame of shoddy quality.

Replacing Worn Consumables

Worn consumables are a common culprit for ugly cuts. Plasma cutter parts aren’t designed to last forever; they wear out and need replacing. There are generally five things that you should count as a consumable on your machine:

  • The shield
  • The retaining cap
  • The nozzle
  • The electrode
  • The swirl ring

Here’s a general rule for when to replace the nozzle: If the hole looks kind of oval-shaped or bigger than it’s supposed to be, change it. It’s good practice to replace the electrode and the nozzle at the same time.

Generally, a visual check will be enough to let you know what needs replacing. If you have an extra one of everything in your toolbox, you’ll know what these things are supposed to look like when in good order. The other perk is that you won’t be waiting for replacement parts to be delivered when your setup isn’t working correctly.

Firmly Secure The Project

Not only do you want to ensure that your project gets a good connection, which I’ll discuss further in a moment, but you want to make sure it is secure. Having a fast workpiece makes cutting a lot easier when there is no fear of the project wandering or moving while you are cutting.

Using hand-held plasma cutters is where I would want to ensure my workpiece is firmly secured. And don’t forget to keep in mind where the cuts will occur. You don’t want to inadvertently cut off the portion of the project where the clamps are fastening the project to your cutting table.

Checking the Earth Clamp To Ensure Your Circuit Is Connected

Ensure that your earth clamp (sometimes referred to as ground clamp) has excellent contact with the workpiece. Otherwise, the connection could end up being intermittent, and it’ll mess up your cut.

If there’s any rust, paint, mill scale, or another kind of coating on the metal, pull out a flap wheel grinder and clean the area you want to clamp down to the bare metal. It will help to ensure a nice, steady connection for the system to work smoothly.

Clean Air for Plasma Cutting

If your compressed air has moisture or oil, you will have a miserable time keeping your consumables in good condition and your cuts clean.

The easiest fix to this is to simply install an inline filter that will take care of the problem. Inline filters are relatively inexpensive and are available at most hardware stores, which also sell air compression equipment.  

The filter is essential for maintaining equipment in a suitable condition. Contaminants in the air can adversely affect the longevity of your equipment. Not to mention the frustration and aggravation that bad plasma cuts will inspire. For an example of a typical inline air filter, take a look at this one from Northern Tool.

Air Filter For Compressed Air Line

Standoff Distance

The arc should be kept between 1/16” and 1/8” above the workpiece. Electric arcs can be finicky, so if you don’t maintain this, you’ll probably have some significant issues.

If you’re using a plasma table, you should have a function where the controller will automatically take care of this. Even if you’ve tried everything else and nothing is working, then maybe just double check to make sure that this is functioning as it should.

Use a Drag Shield for Handheld Units Over 40 Amps

Under 40 amps, this doesn’t matter. But if you’re using a hand-held machine over 40 amps, then a drag shield is an excellent idea. It just removes one more thing that you’d need to concentrate on while cutting.

A drag shield is just a little tube type that fits your torch’s business end. If you let it slide against the workpiece, it’ll maintain that consistent distance between the torch and the work.

If you don’t have a drag shield and are opposed to spending a couple of bucks to pick one up, you’ll have to pay close attention to the torch movement. Most people find it easier to use both hands when cutting like this. One hand holds the torch and guides the action; the other hand props up your cutting hand to keep the torch height steady.

Seriously, though, just get the drag shield.

CNC Plasma Machine Settings and Setup

The owner’s manual is a beautiful source of information on how to set up your equipment. I would know, I read one once.

Anyway, if you still can’t figure it out after thirty-something tries on your own, it might be time to swallow your pride and look around for that condescending little booklet. It should have a bit of information that describes what the machine is capable of and how to handle different materials and thicknesses.

One thing that you’ll want to make sure of is that you’re using the right tip for the amperage setting. You should have at least one tip for high amperage and one tip for low amperage. Running the wrong tip for the set amperage will lead to premature wear. That means that you’ll need to either fork up some cash or suffer the shame of shoddy quality.

Plasma Cutting Techniques – Piercing

Sometimes you can’t blame your tools. The problem might be you. Here are some things to watch out for when you’re using your equipment.

Piercing

When piercing through the thicker material, start with the torch on a 45-degree angle. It will help to prevent backsplash when the molten material sprays back as the plasma is working through the material. If you keep the torch at a 90-degree angle for thick piercing, the backsplash will wear out your consumables, which will, in turn, affect your cut quality.

For thinner material, though, this isn’t necessary. The plasma will punch through the metal quickly and efficiently. Here are a few things people commonly also ask about plasma cutting.

Frequently Asked Questions About Plasma Cutting

What Shade Do You Need For Plasma Cutting?

The shade required for plasma cutting will depend upon the amperage and material. As a general rule, most cutting under 60 amps will use between a #3 and #6 shade. According to ANSI Z49.1:2005 recommendations, the suggested shades are as follows.[Source]

AmperageSuggested Shade Number
Less than 204
20 - 405
40 - 606
60 - 808
80 - 3009

What Are Plasma Cutter Tips Made Of?

Copper is the most common type of plasma cutting tip. However, several consumable components make up the plasma torch; it isn’t just a tip.  

Inside the torch head, there is an electrode. This electrode directs the plasma through the nozzle. Typically the electrode is made of copper (sometimes silver) with a few additives such as hafnium or tungsten.  

How Fine Can A Plasma Cutter Cut?

The quality of a plasma cut depends on the thickness and type of material, the consumables, gases, and amperage. Generally speaking, a hand-held plasma cutter will be able to cut as fine as about ⅛” across. Greater precision than this requires specialized CNC controlled equipment. There is a maximum threshold that you can cut due to the nature of plasma and melting temperatures of materials.

Which Plasma Gas Gives The Best Results For Cutting Mild Steel?

Filtered air provides the most versatile solution for plasma gas type when cutting mild steel and other types of conductive metals such as stainless steel, and aluminum. It is important to note that the air is filtered. Filtering the air provides a cleaner cut as well as prolonging the longevity of your consumables and equipment.

Can You Weld With A Plasma Cutter?

Plasma cutters are not able to be used as welders without alterations. In standard OEM setup, a plasma cutter will only be able to cut conductive metals. Although you may be able to spot melt two metals together, the weld may not hold due to a lack of additives such as flux. Follow all manufacturer recommendations when it comes to the use of the equipment, and it’s intended purpose.

Conclusion

Plasma machines are very reliable and work great when they’re correctly maintained. If you’re just starting with plasma cutting, it can take a little bit of practice to get nice, clean cuts that don’t have globs of slag on one side.

Even if you’re not doing the best job of cutting, this slag generally isn’t very hard to tidy up. A wire wheel or a quick grind should blast it off, no problem. But if you take a bit of time to practice with some test cuts, you should be able to get a plasma cut that looks nearly perfect.

Post a comment below and let us know what you do to improve your quality when plasma cutting.

Share With Friends

Share on facebook
Facebook
Share on twitter
Twitter
Share on linkedin
LinkedIn
Share on pinterest
Pinterest

ABOUT GizmoPlans

Hey, this is Brian and Gene Luoma. Since the two of us have pretty much been self-employed our entire lives, we have a lot of experience designing and creating all sorts of DIY projects for businesses and homes—projects that have helped us make money or save money through the years!

Gizmoplans is our way to share our culmination of years of experience, along with our catalog of projects—both new and old—that we hope will help you, too. If you’re interested in saving or making money, browse on through. We hope you find something here that inspires and helps you to DIY!

LEGAL INFORMATION

This site is owned and operated by GizmoPlans.com LLC. Gizmoplans is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Gizmoplans.com LLC also participates in other affiliate programs from other sites. GizmoPlans.com LLC is compensated for referring traffic and business to these companies.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top
Get 13 FREE DXF FILES - DESIGNS valued at $139.95!

Get the files and stay informed
on Future FREE designs,
discounts & special offers.

(Instant Access)

'}]}