CNC laser cutting machine Full-time Job

While each cutting process has its advantages and disadvantages, this article focuses on laser cutting, outlining the basics of the laser cutting process and the necessary components and mechanics of the CNC laser cutting machine. Additionally, the article explores various laser cutting methods and applications, the benefits and limitations of the process, and comparisons between laser cutting and other types of cutting processes.  

The Laser Cutting Machine and Process

Laser cutting is a non-contact, thermal-based fabrication process suitable for metal and non-metal materials. For the laser cutting process to run smoothly and at optimum capacity, several factors should be taken into consideration, such as the flatbed CNC laser cutting machine’s configuration and settings, the material being cut and its properties, and the type of laser and assist gas employed.

Stimulated Emission: The photons that are produced by spontaneous emission travel within the medium, which is contained in a cavity of the laser resonator between two mirrors. One mirror is reflective to keep photons traveling within the medium, so they continue to propagate stimulated emissions, and the other mirror is partially transmissive to allow some photons to escape. Stimulated emission is the process in which a photon (i.e., the incident photon) stimulates an atom that is already at a higher energy level. This interaction forces the stimulated atom to drop to its ground state by emitting a second photon of the same fixed wavelength or coherent with the incident photon.

The process of one photon propagating the emission of another photon amplifies the strength and intensity of the light beam. Thus the stimulated emission of light photons (i.e., a type of electromagnetic radiation) causes the amplification of light; in other words, light amplification by stimulated emission of radiation. Improperly aligned photons within the resonator pass through the partially transmissive mirror without being reflected into the medium, generating the initial laser beam. Once generated, the beam enters the laser cutting head and is directed by mirrors into the focusing lens.

Chemical Degradation: Chemical degradation is employed by high end laser cutting machine and is suitable for laser cutting thermoset polymers and organic material, such as wood. As thermoset and organic materials do not melt when heat is applied, the laser beam burns the material instead, reducing it to carbon and smoke.

Evaporation Cutting: Evaporation cutting is employed by CO2 laser cutting machines and is suitable for materials such as laser cutting acrylic and polyacetal due to the closeness of their melting and boiling points. Since the laser evaporates material evaporates along the cut, the edge produced is generally glossy and polished.

Scribing: Scribing is employed by CO2 and Nd:YAG laser cutting machines to produce partial or fully penetrating grooves or perforations, usually on ceramics or silicon chips. These grooves and perforations allow for mechanical breaking along the weakened structural lines.

Oxidation Cutting: Also referred to as flame oxygen cutting, oxidation cutting is employed by CO2 and Nd:YAG laser cutting machines and is suitable for laser cutting of mild and carbon steel. Oxidation cutting is one example of the reactive gas melt shearing cutting mechanism, which specifically employs chemically reactive assist gases. As with inertness, the reactivity of an assist gas is relative to the material being cut. Oxidation cutting, as the name implies, employs oxygen as the assist gas, which exothermically reacts with the material. The heat generated accelerates the cutting process and produces an oxidized melted edge which can be easily removed by a gas jet to allow for a cleaner, laser-cut edge.

Beam Movement

Once the localized heating, melting, or vaporizing has started, the machine moves the area of material removal across the workpiece to produce the full cut. The machine achieves the movement either by adjusting the reflective mirrors, controlling the laser cutting head, or manipulating the workpiece. There are three different configurations for low power laser cutting machine, defined by the way in which the laser beam moves or is moved over the material: moving material, flying optics, and hybrid laser cutting systems.

Moving Material: Moving material laser cutting machines feature a stationary laser beam and a movable cutting surface to which the material is affixed. The workpiece is mechanically moved around the stationary beam to produce the necessary cuts. This configuration allows for a uniform and consistent standoff distance and requires fewer optical components.

Flying Optics: Flying optics laser cutting machines feature a movable laser cutter head and a stationary workpiece. The cutting head moves the beam across the stationary workpiece in the X- and Y-axes to produce the necessary cuts. The flexibility of flying optics machines is suitable for cutting materials with variable thickness and sizes, as well as allowing for faster processing times. However, since the beam is continually moving, the changing beam length has to be taken into consideration throughout the process. The changing beam length can be controlled by collimation (alignment of the optics), using a constant beam length axis, or employing an adaptive optics or capacitive height control system capable of making the necessary adjustments in real time.

Hybrid: Hybrid high power laser cutting machine offer a combination of the attributes found on moving material and flying optics machines. These machines feature a material handling table that moves on one axis (usually the X-axis) and a laser head that moves on another (usually the Y-axis). Hybrid systems allow for more consistent beam delivery, and reduced power loss and greater capacity per watt compared to flying optics systems.