Air Assisted Laser cutting
Using compressed air as a laser cutting gas can greatly reduce your laser running costs and help increase your profitability
Cutting gas supply is an essential part of laser cutting but it is also the most expensive utility that you need to supply to your laser cutter. Common cutting gases are nitrogen and oxygen, but the cost of supplying these gases alone can be as high as 90 percent of the total utility cost for the laser.
Depending on the type and the thickness of the material being cut, compressed air can be used as a cutting gas. Compressed air production costs are only one quarter the cost of supplying nitrogen or oxygen!
Why use compressed air for laser cutting?
- Cost Effectiveness - Compressed air is considerably less expensive than both nitrogen and oxygen.
- Speed - Depending on the material and thicknesses, compressed air can give faster cutting rates and increased throughput.
- Compressed air is already used on site - Compressed air is a versatile utility and is probably used elsewhere on site and in your manufacturing process (such as for other machine tools, dust extraction and automation machines that are connected to your laser)
How Does Air-assisted Laser Cutting Work?
No single cutting laser rely strictly on a light beam for cutting metal. Rather, the process includes the injection of an assist gas at the nozzle to supplement the process. This confluence initiates a process known as an exothermic reaction—a chemical reaction that releases energy by light or heat. The introduction of nitrogen, oxygen, or air helps transfer heat more effectively than the beam alone.
Initially oxygen was the most popular gas for the laser cutting process. Later it was discovered that nitrogen produced a cooler cut, resulting in cleaner edges, perfect for industries where aesthetics and edge quality were critical. While nitrogen remains the most widely used laser cutting gas, air is proving to be an effective and cost-saving alternative for a growing number of fabricators.
This is not to suggest that air-assisted cutting is a radical departure from nitrogen or oxygen. Air is, after all, approximately 80 percent nitrogen, with the rest consisting primarily of oxygen. The goal with air-assist cutting is to use this high concentration of nitrogen while at the same time leveraging the added benefits of substituting a slightly more diluted gas.
What Are the Advantages of Air-assist Laser Cutting?
While relatively new to some, air-assist cutting has been around for nearly 25 years. Since the beginning, the use of air as an assist gas has continued its steady growth in popularity among laser users alike. Mode quality was a major limitation when compressed air was first introduced for CO2 lasers, but that has improved significantly. Today air-assist is an efficient and popular method for cutting a variety of materials, even stainless steel and aluminum.
Air carries with it a substantial return on investment for those employing fiber lasers or those cutting stainless steel.
The intense heat of fiber lasers, combined with injected air, creates cuts without producing an oxide formation on the cut surface. This means that secondary cleanup operations are significantly reduced or even eliminated.
As any fabricator using nitrogen will tell you, it is a costly gas. In some instances, the cost of the gas alone can be as high as 90 percent of the total operating cost. Air is considerably less expensive than both nitrogen and oxygen.
Another advantage of air is the faster cutting and increased throughput it delivers. Cutting tests on the full range of materials and thicknesses prove this out.
For example, for material thicker than 10 gauge, tests have shown that nitrogen produces faster cuts, but in the mild steel range of 3 mm and thinner, air is roughly 3 percent faster than nitrogen. In the stainless steel range from 20 mm down to 1 mm, air is about 22 percent faster. In the aluminium range from 5 mm down to 0.8 mm, air is approximately 14 percent faster.
When Should Air be Used as an Assist Gas in Laser Cutting?
Something as common as air can deliver measurable cost and productivity improvements. While air is generally used to cut thin material, most stainless parts, especially those used in assemblies, are candidates for air-assist laser cutting.
While clearly not the best gas in all instances, generally speaking, air produces a laser-cut edge quality that is at least comparable to parts cut with oxygen or nitrogen. In fact, if one were to label nitrogen edge cut quality as a 10, then the edge quality resulting from an air-assist cut would be about an 8. Air-assist edge quality is more than satisfactory for most powder coatings to adhere to, eliminating the need for secondary cleaning operations.
Still there are times when nitrogen remains the best gas choice. Nitrogen produces a cleaner cut, and those serving customers throughout the food processing and aerospace industries should continue their use of the gas.
Additionally, some cosmetic parts cannot show any blemish whatsoever. Again, these types of parts would not be candidates for air-assist cutting.