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Plasma cutting – How to get a better cut (Part 2)

Thursday, January 26th, 2012

A main issue often encountered with plasma cutters is angularity or “beveling” of the cut. Nearly all standard definition plasma cutters will exhibit some beveling. You’ll find more or less beveling between brands as well. Too large of consumables for the cut is a primary cause of beveling. Sizing consumables for the amp output of the cut will keep the beveling down. Drag cutting and moisture will also cause issues with beveling by increasing the wear on the consumable, and opening up the orifice to a larger size, even “angling” the hole in the nozzle, creating a more exaggerated bevel. Using a rolling stand off, or specially designed consumables that can protect the orifice where the flame exits by preventing the area from contacting the metal, will increase the life of the consumable. Of course using special dryers that you’d use in a paint booth, will increase consumable life as well. Reducing piercing, and plunge cuts will prevent the blowback of material on the torch face that creates rapid wear as well. Managing a consistent but minimal standoff height manually poses some challenge but is possible. Practicing will result in improved muscle control and smooth movement to reduce beveling caused by off angles caused from holding the torch wrong as well. Additionally, you will find that a torch will have a natural side, to which the bevel will always turn. Taking note of this will help in cases where the bevel is angled to the throw away side of the material.

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Plasma cutting – How to get a better cut (Part 1)

Tuesday, January 24th, 2012

If you have ever plasma cut very long, you’ll notice a few “odd” quirks with almost any machine. First, you will notice that the cut will reflect nearly every bobble or twitch of your hand, with a jagged edge as a result. Granted plasma cutting makes an extremely smooth cut with a CNC, the plasma cut is only as good as the hand that holds the torch.

To stop the “shakes”, consider using a cutting guide, where you can draw the torch along a solid cutting guide. Make sure it is smooth, and compatible with the torch you are using. Usually a small piece of flat bar is all that is needed. Some people use a piece of wood trim. What is important is that it is true and straight. For circles, a circle cutter can be fabricated or bought from online or from your local welding supply store. For varied curved cuts, rough templates can often be made from a “free hand” run, then ground or machined smooth to offer a smooth guide surface for the torch side to run on. Also, blood sugar, and fatigue play an often overlooked role in how well you can cut. Believe it or not, late afternoon cuts between lunch and supper can yield the worst cuts. Try eating a small snack or meal whenever it’s been more than a couple hours after meal time. This will help increase hand/eye coordination, and steady the nerves as well.

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Plasma Cutting – selecting the best start type

Monday, January 23rd, 2012

Little thought is given by most purchasers of plasma cutting systems about the starting of the arc, and how it is accomplished within the unit. But this is an important issue that the purchaser should be aware of, because each of the three major start types offer distinct advantages and disadvantages. Below are a list of the three basic types, and what you need to know to make the best choice for you when selecting a plasma cutter.

1)       “Blowback” start. This start type uses  air pressure supplied to the cutter to force a small piston or cartridge inside the torch head back to create a small start between the inside surface of the consumable, ionizing the air, and creating a small plasma flame. This also creates a “pilot arc” that provides a plasma flame that stays on, whether in contact with the metal or not. This is a very good start type that is now used by several manufacturers. It’s advantage is that it requires somewhat less circuitry, and is a fairly reliable.

2)      High Frequency start. This start type is widely employed, and has been around the longest. Although it is older technology, it works well, and starts quickly. But, because of the high frequency high voltage power that is required generated to ionize the air, it has some drawbacks. It often interferes with surrounding electronic circuitry, and can even damage components. Also a special circuit is needed to create a Pilot arc. Inexpensive models will not have a pilot arc, and require touching the consumable to the work to start. Employing a HF circuit also can increase maintenance issues, as there are usually adjustable points that must be cleaned and readjusted from time to time.

3)     A much less, common and more expensive start time, is an inductor circuit start. This uses a high voltage, lower frequency current to ionize the air. Torches are similar to the HF torches, if not identical. The start is very quick, and interference is minimal. However, it is a more costly design, due to the component requirements to make such a design. This start would seem ideal compared to HF and blowback, if the cost was more reasonable. Very few companies use this design, because of it.

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Tips to make your plasma cutter work more efficient

Friday, January 13th, 2012

Plasma cutting is a very important process that is used quite predominantly for cutting steel and other metals of varying thickness using plasma torch in the welding industry. In order to create sturdy and high quality product the industry considerably relies upon good plasma cutters for cutting metals precisely as per their requirements. Irrespective of what kind of welding procedure you follow, every welder requires a good plasma cutting tool to create proper welds.

Here are five tips to make your plasma cutter work more efficiently.

  1. Cleaning your ground location is very important. Every welder requires a clean solid ground to create a strong arc in order to easily cut through the metal. A stable arc is what every welder needs to create proper welds. With a subpar ground your arc is mostly bound to be unstable.
  2. Your torch should be slag free as well. Slag plays a predominant feature while cutting metals. This slag can make its way inside your plasma torch electrode or nozzle. This leads to poor cutting ability and spoils the whole purpose.
  3. Plasma cutters needs dry air while cutting. There should be a constant flow of dry air for better efficient cutting. Your compressor should have an adequate dryer and water separator involved. Without dry air, the plasma torch won’t be able to create a stable arc once again.
  4. Avoid using extension cords. The plasma cutter always works better when closer to the power source. Extension cords alter the voltage supply your cutter requires for carrying out the cutting process which hampers your weld.
  5.  Your plasma cutter requires adequate amount of air pressure for the torch to properly “punch” through the metal.

There are several welding forums online giving you more tips and guidelines related to welding concepts. Use them for better welding experience.

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Plasma cutters yielding maximum production output

Wednesday, November 16th, 2011

A method that slits dissimilar metals of diverse width by using a plasma torch is called as plasma cutting. Inert gases are used and it is blown at a high speed with an electric current to generate a potent torch that can cut through metal. The welding equipment that is used for doing this particular process is called a plasma cutter. Also it is one of the welding tools that form a thin brook of plasma and it is adequate to melt the metal with smooth and cleaning process. It can cut large sheets of metals.

With plasma cutters you can do intricate patterns in metal. Metal cut-out can also be formed with the help of a plasma cutter as the tip of the plasma cutter can make very fine incisions on the metal.

Since it makes use of furious gas, as soon as it is discharged from the nozzle it can cut almost any metal of any thickness in few minutes and yields maximum production output.

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Mechanisms of a cutting torch

Friday, November 11th, 2011

The plasma cutting torch clings to the electrode in an exceedingly dug in compartment where gas is heated to plasma.

The utmost tip of the torch cleaves to the contracting hypodermic with an orifice for the bend and plasma to pass through. The arc is tapered into a focused plasma line of ionizing gas that is proficient to transmit much more force than a regular welding arc.

The degree of flame is intense and focused then the heat allows for quicker cuts and less distortion.

Some exclusive plasma cutting systems make use of Nitrogen and other gas mixes. But the more cost-effective and well-liked forms of plasma cutters just draw on dried out condensed air to generate the plasma gas by spinning it in the torch where the unpreserved electrode and nozzle intermingle. Thereby the process is carried on.

An Oxygen/Acetylene Torch is the best tool used for cutting steel to size and shape and it is used in some projects concerned to building. It is one of the dangerous cutting methods however, by following certain safety measures the work is done easier. Comparatively to this the other tools are not much efficient.

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The Plasma Cutting Process : PAC

Monday, October 3rd, 2011

Plasma Arc Cutting (PAC) is probably one of the single most coveted items in a well equipped shop. Almost all commercial shops are equipped with Oxy-fuel for cutting. In fact, I can’t think of any reason a commercial shop would not have a Oxy-Acetylene rig. But up until the last 10 years, many established shops did not have a plasma cutter. A few still don’t. As technology has improved, and prices have gone down and availability has gone up, more and more shops and even hobbyists are making the plasma plunge.

What makes plasma so desirable? It would be difficult to pinpoint any one feature. Plasma cutters are capable of making extremely clean and accurate in any metal, something that cannot be done with Oxy-Acetylene torches. Speed is another factor, with plasma having an edge over Oxy-Acetylene when trying to achieve similar cut quality. Low temperature input also reduces metal distortion while cutting. A major deciding factor for most is the relatively low skill required to operate one. Almost anyone can turn out competent cuts within a short amount of time with just a little practice. Most plasma cutters are easily taken right to the site to work. There’s no dangerous gases to work with. There’s no large bottles to carry around or fill. Most plasma cutters use air compressors which are already found in many shops. Air hoses can be run quite a long ways to the unit giving a lot more portability around the shop with a reduced foot print. Some plasma cutters even have the compressor built in and will operate on 120 volts, allowing it to be used almost anywhere in or out of the shop.

There are some drawbacks to plasma though. While plasma may give Oxy-Fuel a run for its money on performance cutting, it cannot be used in situations where it is necessary to heat metal. Nor can it weld or braze. Plasma can only be used to cut or gouge any metal. Oxy/Acetyelene will weld, cut, braze and heat…though it is limited mostly to steel on cutting. The initial purchase of a plasma system is much higher as well, especially if an air compressor is needed. Consumables should always be kept handy as this is a wear item that is constantly needed. Also, electricity is needed and may be a limiting factor in remote locations. Oxy-Fuel rigs have no such requirements. Torch tips for Oxy-Fuel last much longer for sure and rarely need replacing.

Carefully evaluate your needs and capabilities before purchasing a plasma cutter. It is not a good fit for everyone. It is not a substitute for a good Oxy-Fuel rig because of its limitations. But if you do feel it’s a good fit for you, Everlast offers a full range of plasma cutters from 50 to 100 amps, with cutting capacities up to nearly 2 inches. Well priced from $700 dollars, there’s probably a unit that will fit your needs.

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Need for Water Shroud in Plasma Cutters

Tuesday, May 10th, 2011

The plasma can be made to function with a water shroud or in an alternative case by submerging the work piece for some 50 to 75mm below the surface of the water. Either ways, water is used to keep the condition or temperature of the process under control.

Unlike in the usual plasma cutting methods, we can find that the water takes the role of being the barriers. The advantage of Water Shroud in plasma cutters is that it reduces fumes, decreases noise levels to a great extent and improves the life of the nozzle.

In a usual method the noise levels were noted to be at high current levels of 115dB. But for the conventional plasma cutting machine we can note that the water shroud played a vital role in reducing the noise level to about 96dB.

Seeing that the water shroud will not add to the quantity of constriction, we can note that the squareness of the cut edge as well as the cutting speed is improved to a great extent.

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What is High tolerance plasma?

Monday, May 9th, 2011

Unlike in normal plasma cutting method in which there is no sharp or squireness in the edges we can get the right result that we need in this method. Getting an improved cut quality is no more difficult as we have High Tolerance Plasma Arc cutting, that are also known as HTPAC systems. These High Tolerance Plasma Arc cutting are obtainable with an extremely constricted plasma flow.

To be precise we can say that High Tolerance Plasma Arc cutting method is an automatic technique which requires accuracy, speedy tackle. We can get great results with thicker sheets starting from a minimal thickness of about 6mm.

Apart from this the cutting speed of these High Tolerance Plasma Arc cutting method is usually lesser than the usual plasma processes and can be calculated to be just about 60 to 80% the speed of a laser cutting method but still give a great cut at the end. The Cut quality lies between a usual plasma arc and the laser beam with Narrow kerf width. As the heat affected zone is very small, there is less or very minimal distortion.

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Water injection in the Plasma Arc Cutting Process

Friday, May 6th, 2011

As we all know water is used as a coolant in many industrial methods that involves high temperature for the process. Same ways water injection in the plasma arc cutting process also has a specific use. Water is injected through the injector into the plasma arc.

The plasma arc is generally got when Nitrogen is used as plasma gas in most of the plasma cutting machines. When the water is introduced to the plasma arc it induces a high degree of constriction. We can note that the temperature shoots up considerably to 30,000°C and above in this particular process.

If you compare the above process advantages with conventional plasma you can notice that there is a substantial Improvement in cut quality as well as squareness of cut. Apart from the improvement in cut quality we can also find an increase in cutting speed, less noticeable risk of double arching as well as decrease in nozzle erosion.

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