Laser oxygen cutting requires extremely high levels of both purity and quality in the gases used for its execution. Even minimal contamination of the oxygen jet by other gases can result in substantial losses of exothermic energy.
This has an impact on the speed at which cutting takes place and the final quality of the cut. Cognisant of the impact that impure oxygen can have on the final product produced by laser oxygen cutting, industrial and specialty gas products and chemicals company, Air Products South Africa, has a specialised plant that produces Lasox, the high purity laser oxygen.
“Our Cryoease division, which produces and supplies Lasox, specialises in providing an on-site gas supply solution. This is in comparison with the traditional method, of swapping full for empty cylinders for smaller volume consumption. The Cryoease supply mode features specially designed tankers with integrated controls and flexible storage tank options. End user applications range from pure gas supply, cryogenic liquid supply or gaseous mixtures applications via a mixing panel installed at the customer’s site,” explains Gary Lombard, Cryoease Business Manager at Air Products.
Lombard says that the Cryoease concept was developed as a means of proactively working with customers to ensure a constant and consistent supply of gas. “Customers can not afford to have an interrupted supply of gas, so we developed Cryoease, to provide the assurance that their gas requirements would be met. In addition, with Air Products’ telemetry monitoring systems, the customer’s gas consumption can be monitored and forecasted, and their product will be automatically replenished when required.
“The choice of laser cutting gas is extremely important and can have a significant effect on the process in terms of quality and productivity,” says Lombard. “The two main gases used for laser cutting are oxygen and nitrogen. The decision to utilise one gas over another is dependent on the specific application and metal type.”
The laser cutting process relies on the high energy of the laser beam, concentrated to a spot of about 0.2 mm in diameter, to vaporise the metal. The molten metal is then blown from the cut area by a coaxial jet of assist gas to perform the cut.
“Oxygen purity plays a critical role in achieving the high levels of exothermic energy required for laser cutting and is an important parameter when cutting steel. Using oxygen with purities above 99.95% can increase the cutting speed; the standard industrial grade of Oxygen is 99.5%. Cutting speeds can be increased by 10–30 %, depending on material thickness and the type of steel, which leads to increased productivity and produce products that require less re-work. The Cryoease concept provides a total solution that offers customers further benefits in terms of efficiency and quality,” says Lombard.
Lombard cautions that not many companies are able to produce high purity oxygen in liquid form due to the challenges associated with the process. “Because of its specification parameters, there are only a few plants geared up and capable of this time-consuming manufacturing process. Improved quality specification levels and reliability of supply are the main product differentiators, and form the crux of the Lasox offering.”
“Customers need to consider the long-term effect of using sub-standard industrial gases on their laser optics as well as the final product produced by the laser machine. Original Equipment Manufacturers (OEMs) recommends that high purity gases are utilised by their laser machines and without these gases the performance of the laser cannot be guaranteed. To ensure optimal performance and lifetime, lasing gases must consistently meet the specifications for quality and composition set by the laser manufacturer. Impurities in the lasing gas such as hydrocarbons can damage the laser optics, eventually resulting in shutdowns for cleaning or replacement of the optics. It is not really worth sacrificing on time and quality, when the OEMs of laser cutting equipment are specifying the use of high purity oxygen,” Lombard concludes.