A Cut Above

A wide range of advantages offered by fiber laser cutting technology renders it the preferred choice over CO₂ for flat sheet metal processing.

Fast processing speeds, high process quality, high wall-plug efficiency, superior reliability and minimal maintenance requirements are key reasons fabricators turn to fiber laser cutting technology for sheet metal processing. As fiber laser cutting machines become even more flexible – able to cut a wider range of material types and thicknesses using higher power laser sources and with larger sheet carrying capacity – the advantages are amplified. For flat sheet metal cutting, the fiber laser is the technology of choice.

A better edge

In its infancy, fiber laser cutting was best suited for thin materials (6 mm thick or less). While fiber was able to cut stainless and aluminum, the quality of the cutting edge was inferior to CO₂. As fiber technology has matured, so has its capability. Today, fiber lasers can match or outperform conventional CO₂lasers on thick materials, including mild steel, stainless steel and aluminum. The fiber laser is also able to process non-ferrous materials such as copper and brass as its shorter wavelength is better absorbed by these highly reflective and conductive materials. The modern-day fiber laser is suited to cut both thin and thick materials and a range of material types.

Auto focus/zoom

Advancements in cutting head design help make the fiber laser more flexible. The machine controlled and automated independent adjustment of focus position and focus diameter (so called, “zoom focus”) is one such advancement. Available on certain models of fiber lasers, zoom focus control can dramatically improve piercing times, cutting speeds and cut performance in all material types and thicknesses, increase throughput and reduce the need for operator intervention.

To make zoom capability possible, a collimator was introduced in the area above the cutting head, using two additional optics. Both optics are motorized and can move independently, much like a zoom lens in a camera, allowing the focal point to be expanded or decreased. The focus position changes by moving the collimation lens. The focus diameter can be changed by varying the focal length of the collimation. Independent/automatic control of the focus position and diameter makes it possible to cut different sheet thicknesses without manual intervention.

Machine controlled adjustment of focus position and focus diameter will maximize productivity no matter the material or material thickness. However, zoom focus provides a clear advantage when cutting thick material (20 mm). While both conventional and zoom focus laser cutting heads can achieve fast cutting speeds in light-gauge materials, only a zoom head design is recommended for thick
plate processing.

An advanced optical design features motorized adjustment of focus position and focus diameter.

Piercing optimized

Piercing is also better handled by zoom technology. A significant challenge when cutting thick mild steel is to create a fast and stable piercing process. The machine-controlled focus adjustment (zoom focus) optimizes the piercing process by enhancing piercing stability and quality.

Piercing times are significantly reduced in thick mild steel versus CO₂ technology. In part, this is because the absorptivity of metal surfaces is higher for the shorter wavelength fiber laser radiation compared to the longer wavelength CO₂laser radiation. Another factor is the improved (zoom focus) technology in the fiber laser cutting head. By increasing the magnification (spot size), the half angle divergence decreases. This enables a reduced amount of molten material and hence results in faster processing. It takes a high-powered CO₂ laser 10 to 15 seconds to make a small pierce hole in 20 mm thick mild steel. Using a zoom focus cutting head, we can now pierce in only two seconds. Considering an average of 500 holes/plates, the resulting savings can
be significant.

Higher power

Laser manufacturers are developing more powerful fiber laser sources and optical systems, driven by the end-user need to cut a broader range of materials in varying thicknesses. When cutting steel with nitrogen, a 6000 W fiber laser offers significantly more versatility than 3 kW and 4 kW systems. For example, using nitrogen to process 6 mm steel, a 6 kW fiber laser can cut at 5200 mm/min compared to 2800 mm/min for a 4 kW fiber laser.
The higher power level opens the door to cutting a wider range of sheet metal thicknesses, which in turn makes more design and engineering opportunities possible.

LVD recently introduced the 8 kW Electra fiber laser. The machine incorporates a “smooth lead-in” feature, which guarantees a much faster but stable lead-in after fast piercing when cutting thicker material (greater than 6 mm) with Nitrogen, resulting in an average gain of up to 15 per cent on part cutting times.

Uprated

The latest fiber laser cutting machines, like LVD’s Phoenix 4020 and Phoenix 6020 models, feature uprated drive systems able to deliver dynamic cutting performance when processing large format sheets (4000 x 2000 mm; 6000 x 2000 mm). High cut quality is maintained across the entire length of the workpiece at high processing speeds. The ability to process large sheets allows the user to maximize material usage, making the cutting process more cost competitive.

LVD will exhibit the Lynx FL 3015 at IMTEX 2018. Lynx makes entry into the world of fiber laser technology easy in a machine that’s capable, easy to use, and an investment that is within reach for most shops.

Lower costs

Since its introduction, fiber laser has had the advantage of reducing variable costs in electricity, laser gas and consumables. A 6 kW fiber laser uses significantly less energy than its 6 kW CO₂ counterpart, making it more cost-efficient to operate. In one example, the maximum energy consumption of a 6 kW CO₂ was 81.5 kW. In comparison, the same configuration of 6 kW fiber laser had a maximum consumption of 21.1 kW – a dramatic 74 percent lower energy usage rate.

A fiber laser is also low-maintenance, having no mirrors and a simple beam delivery system. In fact, fiber laser sources can be virtually maintenance free, providing consistent power delivery for thousands of hours without the need for any maintenance intervention.