In the field of laser cutting, especially for processing high-reflective metals such as copper, brass and their alloys, the selection of the cutting nozzle is of vital importance. Among them, single spray and double spray are the two main structural forms, which have fundamental differences in design, working principle and applicable scenarios.
1. Structural Design Differences
Single nozzle
The structure consists of a single gas channel. Inside, it is typically composed of a cone (vortex ring) and the nozzle body, forming a circular gas flow path.
The high-pressure auxiliary gas (usually nitrogen or oxygen-free compressed air) is ejected from this annular flow channel, forming a converging and collimated gas flow.
Double nozzle
The structure consists of two independent and coaxial gas channels. The inner layer is the main cutting gas channel, whose structure is similar to that of a single nozzle. The outer layer is an additional, independent annular gas channel.
The dual-injection structure enables two gases (or the same gas but at different pressures) to operate simultaneously through the inner and outer channels.
II. Working Mechanism and Core Functions
Working Mechanism of a Single Nozzle
Its core function is to generate a high-speed and stable gas jet. This gas flow has three main effects:
Forming protection: Blow away the molten metal at the cutting edge to complete the cutting.
Protecting the lens: Preventing the metal splatters generated during the cutting process from contaminating and damaging the focusing lens below.
Auxiliary cooling: To cool the internal components of the cutting head.
When cutting high-reflection materials, the single-nozzle airflow design, especially when combined with the vortex gas path, can effectively disperse and attenuate the laser energy reflected into the nozzle interior, thereby reducing the risk of the nozzle itself being damaged by the reflected light.
The working mechanism of the double-nozzle
Its working mechanism is based on the principle of air curtain protection. The internal and external airflows work together:
Inner airflow: Consistent with the single nozzle function, it is responsible for the main cutting task, namely piercing through the material and blowing away the slag.
Outer air flow: Forms an "air curtain" that surrounds the inner main air flow. The main function of this air curtain is:
Enhanced anti-reflection: The outer airflow can more effectively cool and clean the nozzle end face, and further block and scatter the laser energy reflected back from the workpiece surface, providing a higher level of protection for the nozzle and the cutting head.
Improving cutting stability: The outer airflow helps stabilize the inner main airflow, reducing the turbulence within the cutting edge, thereby potentially achieving a smoother cutting surface.
III. Comparison of Performance Parameters and Application Scenarios
The fundamental difference between single-nozzle and double-nozzle copper cutting nozzles lies in the design and control of the gas flow field. The single nozzle achieves cutting and basic protection through a single optimized gas flow, featuring economic and practical characteristics. The double nozzle, through the synergy of an inner and outer dual-layer gas flow, constructs a more powerful gas curtain protection system, providing a higher process window and equipment safety when dealing with extreme reflection risks. The choice of which nozzle to use depends on the specific processing material (purity, thickness), process requirements (section quality, speed), and overall cost considerations.