MOVING TOWARDS A BETTER WORKPLACE
This new plasma cutting technology for aluminum, stainless steel and other non-ferrous materials saves energy, is more economical and less hazardous to operate than traditional cutting systems.
Posted: April 18, 2009
No longer a passing trend, "going green" has taken hold on nearly every American industry, from building to advertising to dry cleaning. And this concept of going green has expanded itself to include a variety of healthy alternatives, including safer and healthier workplaces.
With this surge of interest in eco-friendly companies and products, the welding industry has taken the lead to develop new sustainable technologies that will improve our workplaces and the environment as a whole.
Looking to the future in the welding industry, the upcoming years are expected to showcase tremendous growth in aluminum sales. Driven by the material cost of steel and aluminum's quality as a lightweight resource, the difference between steel and aluminum is expected to drastically shrink. Understanding the importance this product will play in the near future, especially in the automotive industry as gasoline prices continue to soar, welding manufacturers must be one step ahead.
Introducing new technologies specifically designed for advanced cutting capabilities with popular metals and metal thicknesses, manufacturers have positioned plasma welders with the necessary tools for success. In addition, these new tools have brought cleaner working environments.
Here we have cut through the clutter to help end users better understand the plasma cutting technologies available and the applications for each in obtaining the best quality cut while also maintaining a safer and healthier workplace.
Water Mist Secondary
Cutting non-ferrous materials, especially stainless steel and aluminum, has always been a challenge for welding manufacturers. Because of the cutting precision required and production prices, the most commonly used technologies for cutting these materials in the past were plasma, waterjet and laser.
However, a recent technology known as Water Mist Secondary offers a more economical and energy-saving alternative. WMS
Compared to the other processes, where argon-hydrogen is used as a plasma gas and nitrogen as a secondary, WMS instead uses nitrogen as a plasma gas and water as secondary (shield gas), providing unique advantages with outstanding results.
The water in the torch is divided into its principal hydrogen and oxygen components during the cutting process. The hydrogen creates a reduced atmosphere in the cutting zone, isolating it from contaminating elements and producing a clean, dross-free and oxide-free cut surface. Then the main amount of the water used during the process – from 4 to 8 gallons per hour – is converted to principal components or evaporates in turn eliminating the need for disposal.
Most effective on non-ferrous materials such as aluminum and stainless, WMS notably reduces production prices, energy and smog levels as a result of the use of normal tap water and offers remarkable results on a very wide range of thickness.
Due to the machine's significant reduction in the creation of smog in the workplace, use of this technology is a good choice for those looking to meet the Occupational Safety and Health Administration's (OSHA) requirements. OSHA is tasked to promote and regulate the safety and health of U.S. workplaces by setting and enforcing standards across individual industries.
Smog's negative effects on the environment due to ozone gas includes reducing plant and crop growth, creating a haze that limits visibility in an area, and causing widespread damage to forests. Likewise, for humans smog can cause severe injuries such as difficulty breathing, asthma, reduced resistance to lung infections and colds, and eye irritation.
Since smog consists of air pollutants that can significantly harm the environment and its inhabitants, OSHA is continually seeking new ways to monitor and reduce an area's smog output. Thus, WMS technology aids OSHA in its endeavor to regulate smog throughout the environment, providing an excellent alternative energy source for plasma cutting.
Argon-hydrogen was the gas of choice for plasma cutting. Used for cutting steels and other metals through a torch, plasma cutting with argon-hydrogen gas is best for middle to high thickness purposes, such as from 3/8 in.
Generally the results of plasma cutting are excellent, both in quality and in speed, but the huge consumption of argon and hydrogen result in middle to high cost per foot of work. As a result, these produce higher levels of smog into the atmosphere due to the harmful chemicals the gases may contain.
Harmful not only to the environment, but to the workers that use them, chemicals in these gases can cause both short-term and long-term effects including, but not limited to, upper respiratory infections, chronic respiratory disease, lung disease and heart disease.
For thicknesses less than 3/8 in, often nitrogen or compressed air is utilized to reduce hourly costs and to eliminate dross. It is difficult to get dross-free or low level cuts below 3/8 in using argon hydrogen mix gases, considering the high heat required of the gas.
The cutting speed is very high when using nitrogen or compressed air, but the quality is compromised from an excessive inclination of the cut or by excessive oxidation. In addition, these gases require extra diligence in cleaning after the work.
WMS technology, on the other hand, allows travel speeds similar to those of plasma cutting, similar cut quality without dross or oxidation on a range of thicknesses from gauge up to 1 in, and a reduction in costs because of the elimination of a secondary gas and a longer life cycle for consumable parts.
Another alternative is cutting with a laser, which has recently taken hold in the aluminum and stainless steel cutting industries. While the laser does offer advantages in cutting speeds on thinner materials and in situations requiring small holes or intricate designs, its drawbacks far outweigh its usage for many types of cutting.
Typically used in the production of industrial manufacturing equipment, laser cutting requires great amounts of power in comparison to plasma cutting especially in the case of aluminum cutting. It also requires high pressures and volumes of nitrogen for non-ferrous materials, about 35 times the amount of nitrogen. So the cost advantage from speed on thinner materials is lost due to the energy consumption necessary. In addition, the system is not advantageous in speed for materials over 1/4 in.
Although lasers are a great alternative in that they do not use gases which clutter the earth's atmosphere, they do rely on heavy amounts of energy consumption, which can result in higher prices and harmful effects to the environment. Most energy sources we depend on, such as coal and natural gas, can't be replaced – once we use them, they're gone. Additionally, most forms of energy can cause pollution, so the less energy used, the better for all.
When there is no need for very small holes or very intricate shapes, cutting with WMS technology can replace laser cutting with an increase in productivity and a remarkable reduction of time, costs and energy.
For high quality precision cutting on a variety of materials – from cotton to wood to metal – waterjetting offers excellent results. The process includes using a very high pressure of water to cut the material.
However, waterjetting is a very slow process which results in higher labor costs. Remember, 80 percent of the costs – no matter what you cut or how – is labor. Therefore, it's important to use manpower time efficiently.
While waterjet cutting is another alternative cutting application that doesn't use gas, it does require large amounts of water, which may put a toll on maniple water supplies. Additionally, high costs are common for waterjet cutting and prices are increased due to the consumption of abrasive materials and energy put in the cutting flow. Yet waterjetting is used in applications for the mining and aerospace industries.
Plasma cutting with WMS can provide a cutting quality very close to waterjet cutting, with speeds much higher and overhead costs much lower in comparison. The productivity of this cutting system makes it a valid alternative, particularly in the range of middle-low thickness -less than 1 in.
With the introduction of green and sustainable trends, wind and solar energy sources have become increasingly popular. These types of applications consider the energy costs essential to success, providing an increased interest in lightweight metals such as aluminum and stainless steel.
For professionals looking to meet OSHA requirements for a better workplace, WMS is the obvious cutting technology of choice. With its clear advantages – user-friendly process, high-quality weldability, high cutting speeds, great sustainability and low energy source costs – this technology is positioned for success in the future, especially in the use of popular non-ferrous materials such as aluminum and stainless steel.
Welding and cutting are hazardous jobs by nature. The type of work required poses several health and safety risks to its workers. However, as manufacturers develop products to improve safety opportunities and lower health risks, these work hazards will begin to decline as alternative solutions are continuously being offered.
Looking to the future, while the other process – plasma, laser and waterjet- are available, the advantages of WMS far surpass the rest, providing the best overall advantage to its users and the environment.
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Dirk Ott is the Vice President, Global Plasma Automation for Thermal Dynamics, 16052 Swingley Ridge #300, St. Louis, MO 63017, 636-728-3000, Fax: 636-728-3021, www.thermadyne.com.
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