Ultra-high-speed fibre laser cutting.
Fibre Lasers: Making their Mark
As fibre laser technology continues to advance and as the installation base of systems grows across the globe, there is more on the horizon as manufacturers continue to strengthen its capabilities. Article by LVD.
Machine gantry plays a role in high cutting dynamics.
In the past 10 years, fibre lasers have made a significant impact on the sheet metal fabrication industry. Today, the fibre laser is the most sought-after solid-state laser and is where most laser development work is happening. In global industrial revenues for 2019, sales of fibre lasers far surpassed those of CO2, disc, diode and other lasers. Fibre laser revenues (51 percent) represented about half the total industrial laser revenues in 2019 (Industrial Laser Solutions, January 2020).
No doubt, fibre laser technology has experienced widespread acceptance in the sheet metal cutting sector and a number of factors have powered its growth. Initially best suited for cutting thin sheet metal at high speeds, today the scope and capability of fibre lasers is so much more.
More power and control
Features like an automatic nozzle changer adds to the efficiency of fibre lasers.
High-powered fibre lasers—6-, 8-, 10-kW—have changed the playing field. While high-powered lasers have existed for more than a decade, it is only within the last four years that laser head technology has caught up, allowing manufacturers to expand the scope of materials and thicknesses that can be cut. As a result, a fibre laser cutting machine with 10-kW source can cut 6 mm mild steel at 12,000 mm/min. Even more impressive is the increase in speed when cutting stainless steel and aluminium.
Advancements in cutting head design have made it possible to change the spot size of the laser giving greater flexibility and optimised cutting speeds over a wider variety of material thicknesses. Modern fibre lasers use a variable beam collimator or “zoom focus” cutting head, which allows the focal point to be expanded when cutting thicker materials and decreased for cutting thinner materials. In this way the density of energy, cutting speeds and piercing times are optimised for each material thickness. A significant challenge when cutting thick mild steel is to create a fast and stable piercing process. The machine-controlled focus adjustment (zoom focus) optimises the piercing process by enhancing piercing stability and quality.
High cutting dynamics
Modern cutting head.
With the use of higher power sources and zoom focus technology, cutting speeds have increased dramatically. A fibre laser can achieve up to 5G acceleration. But leveraging more power and high cutting dynamics is only possible in a machine designed for the job. Basically, if the machine can’t maintain the exact position of the tip of the cutting head at maximum speed and acceleration, the cutting process must be slowed down for parts to keep their desired shape.
The machine frame plays a key role in keeping the cutting head in position at maximum speeds and so is critical to a fibre laser’s cutting dynamics. An extremely rigid frame can ‘contain’ the inertia of the high-speed movement of the cutting head and gantry making it possible to take advantage of higher levels of power. In a machine without such a solid structure, the frame is not able to ‘contain’ the deflection of the frame, which can cause problems with accuracy and shorten machine life.
The machine gantry which holds the cutting head carriage should also be a rigid construction to prevent flexing.
A fibre laser cutting machine that combines both an extremely rigid frame and gantry can maintain high acceleration even while cutting.
Improved efficiencies
Reduced maintenance and operating costs are attractive features of fibre laser technology. The wall-plug efficiency (WPE) of the laser source, which is the ratio of power into the source versus power out at the head for cutting, is a core part of these costs. Latest generation fibre laser sources have pushed WPE from 25 percent to over 40 percent. In comparison, the WPE for CO2 lasers is 10 percent and the WPE for disc lasers stands at approximately 25 percent.
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