Cutting Processes

Metal cutting process: plasma arc, oxy-fuel and laser beam cutting

Precision cutting for precision welds

At Praxair, we’ll work with you to understand your cutting and welding needs and help you choose the most effective and economical cutting process for your operations. See below for some of the differences and advantages of our major cutting technologies.

Oxy-Fuel Cutting -

Oxy-fuel cutting is a cost-effective method of plate edge preparation for bevel and groove welding. It can be used to easily cut rusty and scaled plates and only requires moderate skill to produce successful results. The oxy-fuel gas cutting process creates a chemical reaction of oxygen with the base metal at elevated temperatures to sever the metal. The necessary temperature is maintained by a flame from the combustion of a selected fuel gas mixed with pure oxygen.

The process is based on the rapid formation of iron oxide which occurs when a high-pressure pure oxygen stream is introduced into the cutting envelope. The iron is quickly oxidized by the high purity oxygen and heat is liberated by this reaction. The oxygen stream and combusted gas transport the molten oxide away and the metal in its path burns, producing a narrow cut known as a kerf. Continued iron oxide formation requires large volumes of oxygen to be delivered to the cut zone at a controlled preset pressure. The intense heat produced by this reaction sustains the cutting process and the production of the cut.

Common oxy-fuel cutting applications are limited to carbon and low alloy steel. These materials can be cut economically, and the setup is quick and simple. For manual oxy-fuel gas cutting there is no electric power requirement and equipment costs are low. Materials from 1/16in (1.6mm) to 4in (102mm) thick are commonly cut using manual oxy-fuel gas cutting. Materials 12in (0.3m) and greater in thickness are successfully severed using machine cutting.

Plasma Arc Cutting (PAC) -

Plasma Arc Cutting (PAC) severs metal by melting a localized area of the material with a constricted electric arc that removes the molten material with a high velocity jet of hot ionized gas.

The PAC process can be used to cut any electrically conductive metal if its thickness and shape permit full penetration by the plasma jet. Because the PAC process can be used to cut nonferrous materials, and is faster than oxy-fuel cutting with ferrous material less than three inches thick, it is the most economical alternative for many industrial applications.

PAC equipment is available for cutting a wide range of material thicknesses, and precision plasma can produce laser-like quality cuts in some applications for significantly lower equipment and operating costs.

Plasma arc cutting

Laser Beam Cutting (LBC) -

Laser Beam Cutting (LBC) is a thermal cutting process that utilizes highly localized melting or vaporizing to sever metal with the heat from a beam of coherent light, usually with the assistance of a high-pressure gas. An assist gas is used to remove the melted and volatilized materials from the beam path. Both metallic and non-metallic materials can be cut by the laser beam process. The output beam is often pulsed to very high peak powers in the cutting process, increasing the travel speed of the cutting operation.

The two most common types of industrial lasers are carbon dioxide (CO2) and neodymium-doped yttrium aluminum garnet (Nd:YAG). A CO2 laser uses a gaseous medium to produce the lasing action while the Nd:YAG use a crystalline material. CO2 lasers are commercially available in powers up to 6kW and Nd:YAG systems are available up to 6kW.

Done by mechanized equipment, laser cutting delivers highly reproducible results with narrow kerf width, minimal heat-affected zone and little-to-no distortion. The process is flexible, easy to automate and offers high cutting speeds with excellent cut quality. Equipment costs are high but are becoming lower as resonator technology becomes less expensive.

Laser beam cutting