JSN ImageShow - Joomla 1.5 extension (component, module) by JoomlaShine.com
|
|
Plasma cutting in a nutshell: a step-by-step guide to the process and the materials needed |
|
|
Tuesday, 01 May 2007 |
|
Page 2 of 3
Electrons separate from nucleus
In layman’s terms, plasma occurs when gas reaches an extremely hot temperature. The energy “begins to break apart the gas molecules, and the atoms begin to split. Normal atoms are made up of protons and neutrons in the nucleus, surrounded by a cloud of electrons. In plasma, the electrons separate from the nucleus.
Once the energy of heat releases the electrons from the atom, the electrons begin to move around quickly. The electrons are negatively charged, and they leave behind their positively charged nuclei. These positively charged nuclei are known as ions. When the fast-moving electrons collide with other electrons and ions, they release vast amounts of energy. This energy is what gives plasma its unique status and unbelievable cutting power,” according to www.howstuffworks.com/plasma-cutter3.htm.
How a plasma arc cutter works in simple terms
The difference between plasma and gas is that plasma can conduct electricity and this physical property is the basis of plasma arc cutting. Pressurized gas, compressed air or nitrogen, which is the best gas for cutting stainless steel, flows into the upper chamber of the torch. The electrode is located in the center of the torch. Note that the electrode is the negative part of the electrical circuit that will be created. When the tip of the gun touches the metal that is to be cut, an electrical circuit is established. A powerful spark is produced in the chamber and this spark heats up the compressed air to an extremely high temperature. This generates the plasma gas.
The plasma expands in volume and pressure - up to 30,000 degrees Fahrenheit and 20,000 ft/sec - and is directed in a controlled beam to the metal that is to be cut. The metal heats up to a molten state and the pressurized gas forces open a hole that is the start of the cut line. The gun is moved in a path away from the hole and the metal is severed or cut. The speed and depth at which the plasma arc cutter works depends on a few variables.
Speed and thickness variables
Some of the variables that affect cutting speed and the depth of cut depend upon the voltage, amps (110 volts with produce up 27 amps), air pressure, nozzle size, and the metal thickness. Most plasma arc cutting manufacturers have both 110 volt models as well as 220 volt models. Miller Electric’s 375X-TREME has multi-plugs that can be switched from 120 to 220-volts in a matter of moments, depending on the type of receptacle. I have outlined all the major manufacturer’s machines in a comparison chart at the end of this article.
The next generation of plasma cutters is now using inverter technology. To help reduce the number of variables, I will look at machines that are rated to cut 3/8-inch thick metal at 10 inches per minute. First and foremost by using the 3/8-inch thickness, I cannot think of any part on today’s cars or light trucks (one ton or less) where a tech would encounter a piece of metal that would be that thick. Nearly all of the 120-volt machines will cut a 1/8-inch thickness, but you may have an occasion to cut a thicker piece of metal and it would be nice to have those capabilities at your fingertip. One more item when selecting the right machine is to stay away from any high frequency or capacitor discharge units. They will play havoc on your company phone and computer systems as well as the nearby vehicle’s computers.
|
|
|
