Making their Mark
- August 31, 2020
In the past ten years, fiber lasers have made a significant impact on the sheet metal fabrication industry. Today, the fiber laser is the most sought-after solid-state laser and is where most laser development work is happening. In a 2019 industrial laser market report, Industrial Laser Solutions Magazine says sales of fiber lasers far surpassed those of CO2, disc, diode and other lasers representing about half the total industrial laser revenues.
No doubt, fiber 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 fiber lasers is so much more.
More Power and Control
High powered fiber lasers – 6, 8, 10-kW – have changed the playing field. While high powered lasers have existed for more than a decade, it's 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 fiber 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 aluminum.
Advancements in cutting head design have made it possible to change the spot size of the laser giving greater flexibility and optimized cutting speeds over a wider variety of material thicknesses. Modern fiber 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 optimized 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) optimizes piercing by enhancing stability and quality.
With the use of higher power sources and zoom focus technology, cutting speeds have increased dramatically. A fiber 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 is critical to a fiber 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 fiber laser cutting machine that combines both an extremely rigid frame and gantry can maintain high acceleration even while cutting.
Reduced maintenance and operating costs are attractive features of fiber 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 fiber laser sources have pushed WPE from 25 per cent to over 40 per cent. In comparison, the WPE for CO2 lasers is 10 per cent and the WPE for disc lasers stands at approximately 25 per cent.
New Cutting Technologies
New material types and thicknesses require new application technologies to enhance speed, optimize quality and minimize operating costs. They are implemented in the machine as well as in the programming software and the machine control.
The latest developments include new piercing routines that dramatically reduce piercing times, particularly in thicker materials. For example, a 25 mm pierce on a 6-kW fiber laser is completed in 3 seconds compared to 18 seconds on a 6-kW CO2 machine. As well, new nozzle designs increase processing speeds during nitrogen cutting while also reducing nitrogen consumption up to 30 per cent. Because fiber lasers have a broad processing range, their nitrogen consumption is greater. Nozzle technologies have advanced to reduce nitrogen consumption and even improve edge quality.
More Automation Options
Because fiber laser cutting productivity rates are significantly higher than those of CO2 lasers, many fiber laser users look to add some level of automation to their machine in order to maintain a consistent pace of production. This could be as simple as a load-assist option, but as large-format fiber lasers becoming increasingly in demand (to replace aging CO2 machines), equipment manufacturers are turning their attention to providing flexible, modular automation options for mid-sized as well as large-format flatbed fiber lasers.
Modular tower automation systems and warehouse automation systems are able to feed multiple lasers, thus increasing the productivity of connected machines. These systems keep material flow continuous, production uninterrupted, and sheets and parts organized efficiently, which is key in making the most of fiber laser cutting technology. They help increase throughput without adding additional machinery or personnel. These units offer highly customizable configurations, including single, double or triple tower storage systems, output stations to deliver cut sheets to a sorting area or sorted parts to other machines such as press brakes, and the ability to unload directly on the machine. Many of these systems are retrofittable.
With so many automation options available to fiber laser users, the key is matching the right automation solution to the user’s needs.
As fiber laser technology continues to advance and as the installation base of systems grows across the globe, there is more on the horizon for fiber lasers. Laser power will continue to be important, as will piercing and cutting efficiencies and automation cycle times.
Article courtesy of LVD Strippit.