Laser cutting of thick sectioned steels using gas flow impingement on the erosion front

Abstract

An off-axial gas jet has been developed that has the potential to extend the laser's effectiveness by improving the rate at which parts can be machined, producing high-quality surfaces, enhancing the cutting thickness, and adding to the range of materials that can be machined. In laser cutting, an erosion front (liquid–gas region) forms at the momentary end of the cut. Laser heating, exothermic reactions and shear force between the gas flow and the molten layer dictate the material removal rates. The principle of the off-axial gas jet is to provide straight, nonturbulent flow to the cutting erosion front, causing further oxidation reactions and transferring momentum to the molten slag and dross, thereby improving the cutting speed and the quality of cut. The design features of the off-axial nozzle including the shape, size, gas impinging angle with respect to the erosion front, gas pressure and velocity at the nozzle exit, and the distance between the nozzle and the laser beam are described. Successful test results of the off-axial nozzle in the laser cutting of stainless and carbon steels in the laboratory are presented.

Design and application of laser scanning strategy for machining deep surface grooves with a continuous-wave fiber laser

“…This quickly vaporized the material in the kerf. This rapid vaporization created high-pressure vapor that further eroded the walls of the kerf while ejecting material from the groove [33]. As the absorptivity of metals can be well approximated by an increasing relationship with temperature [12], the concentrated heat density in the kerf owing to the higher absorptivity also intensified the biased groove shapes.…”

Laser Cutting: A Review on the Influence of Assist Gas

“…Ilavarsan and Molian [85] followed the previous experimental approach. Using an off-axial cylindrical nozzle, in conjunction with a converging coaxial one, the cutting speed during reactive gas laser fusion cutting of carbon steel, and 304-stainless steel is substantially increased for thicker plates (plates with thicknesses in a range of 2–4.5 mm); however, the off-axial assist gas did not have any significant effect when cutting thin plates (<2 mm).…”

The development of a laser machining curriculum: An interdisciplinary approach (the MAST program)

“…Due to its non-contact nature, laser processing provides excellent flexibility for interfacing with computer-aided design/computer-aided manufacturing (CAD/CAM) tools and allows precision machining without hard tooling and complex fixtures [1]. One of the principal advantages of laser processing is its ability to cut very hard metals and ceramics that are very difficult to machine using conventional techniques [2].…”