Laser Cutting Machine

Workpieces must be properly prepped in order to ensure a precise cut. Laser cutting can be performed on a wide spectrum of materials, including metals, plastics, composites, glass, rock, fabrics, and more. However, lasers create hazards when applied to certain materials, and other items may not respond well (or at all) to laser cutters. For example, PVC produces highly toxic chlorine gas when burned, and ABS (acrylonitrile butadiene styrene) simply pools and bubbles rather than cutting. Additionally, laser systems can only cut materials up to a certain thickness limit. The limit depends upon the absolute laser power, the beam quality, and the absorption spectrum of the material.

Laser light is generated through a process called stimulated emission (LASER means Light Amplification by Stimulated Emission of Radiation). It begins with a laser medium — a solid, liquid, or gas (unique or blended) whose atomic structure can be excited to higher energy levels. The medium is pumped with energy to generate these higher energy states. This can be done through electrical discharge, optical (flash tube, another laser, etc.) pumping, direct electrical stimulus at a semiconductor junction, or chemical reactions that generate flashes of energy emission.

The process of focusing a laser requires the manipulation of the laser beam to draw its energy into a smaller area. This is typically done with lenses or mirrors and improves the specific energy, power density, and precision in applications such as: cutting, drilling, welding, or laser microscopy. A smaller focal spot results in a narrower cut and a longer focal length creates a more uniform kerf.

The machine's laser cutting parameters need to be optimized in order to get the best possible quality out of the cut. The laser energy level is the main driver in determining the beam's intensity, which, in turn, affects cutting speed and depth. Higher power settings allow for faster cutting but may result in a larger HAZ (heat-affected zone) if not properly tuned. HAZ size is directly related to beam power, beam conditioning, and the response of the target to the incident energy.

Once the machine parameters are validated by testing, the cutting process can begin. The laser cutting machine will follow its programmed instructions. The beam rapidly heats and vaporizes the material. The gas assist blows vapor and droplets clear and cools the post-cut areas, creating a narrow kerf along the desired cutting path.
For larger cutting jobs or when cutting multiple parts, the laser cutting machine will operate continuously unless forced to pause to reposition the workpiece or clean the nozzle. More capable equipment may ‘observe' other reasons for stoppages or operator intervention.

Programmed movement is achieved either by moving the cutting table or the optics head (or occasionally both). Larger machines typically have mobile optics because the optical head has far less mass than a large workpiece, allowing for faster maneuvers. Move time between cuts can suck up significant process time, especially when large plates and heavy loads must be positioned. Smaller industrial machines with lower cutting capacities will commonly move the cutting platform along at least one axis of motion because it simplifies the optical setup. Desktop machines, meanwhile, commonly feature fixed lasers, so all motion is made by the cutting table.