For years, CO2 lasers and plasma arc cutters held the advantage and dominated the market when it came to processing large parts or heavy workpieces. More recently, the efficiency and cost effectiveness of new fiber lasers with high-power 10-kW or 12-kW power sources has allowed fiber laser technology to excel in the area of large-format cutting in applications for steel service centers, shipyards, off-road vehicles, construction, large-plate subcontracting and others.
For shops processing large plate or even cutting a diversity of jobs, a large-format cutting machine means larger productivity gains. Large parts can be processed without repositioning while multiple smaller workpieces can be positioned on the cutting table and processed in continuous fashion, without interruption. Parts can be cut on one section of the table, while offloaded on another, keeping downtime to an absolute minimum.
Industrial fiber lasers continue to broaden in scope while the advantages of more traditional thermal cutting processes like CO2 continue to narrow. Companies with aging large-format CO2 laser cutting machines that are investing heavily in maintaining this equipment are considering their options. Today’s fiber lasers make a strong case for large-format cutting and even extra-large processing.
One key reason is machine design. Many large-format laser cutting machines no longer employ a shuttle table design but are gantry-style designs like the classic oxyfuel and plasma cutters. The advantage of this design is that the limitation in the length of a large-format laser cutting machine now comes down to the available floor space and not the machine construction.
The laser shown on this page is a modular design that begins at a 40-ft. (12-m) bed length and can be expanded in increments of 6.5 ft. (2 m) up to a bed length of 130 ft. (40 m), accommodating workpieces up to 10.8 ft. (3.3 m) wide and material thicknesses up to 1.18 in. (30 mm).
Exceeding limitations
High-power fiber lasers – 10 kW or more – cut at higher speeds and through thin and thick material with greater efficiency than CO2 and plasma. CO2 laser sources have traditionally been large and heavy and have to be carried along by the gantry, which make the machine quite slow. New large-format fiber lasers position the laser source adjacent to the machine. Laser power is transferred to the cutting head by a flexible fiber cable (process fiber).
Harnessing power up to 12 kW in a fairly small area such as a cutting head is no longer a challenge. Today’s cutting head technology incorporates electronics to automatically alert operators of unusual contamination or performance issues with any of the critical components in the cutting head design that are responsible for adjusting the fiber laser’s focal point and its curve width.
Then, there’s the high-speed piercing advantage of fiber laser, which is especially of value when cutting thicker materials. Piercing with CO2 is a long, slow process. New cutting technologies for fiber laser offer rapid piercing routines with a piercing time in thick plate of less than 3 sec. The time saved piercing can be significant. In a shipyard application processing armor plate with an average of 500 holes, almost two hours are spent piercing before a single cut is made. In the same example, the fiber laser reduces piercing time to less than 15 min.
High-power fiber lasers also can comfortably cut small, precise holes in thick materials, which is a shortcoming of plasma cutting. Fiber lasers can produce smaller hole sizes than plasma, sometimes with a diameter half of the thickness of the material or smaller.
Cutting capabilities
Large-format fiber lasers can cut thicker materials and can cut over longer periods of time than CO2 or plasma. On a large-bed table, the operator lays multiple sheets and plates on the table and can process one plate after another with virtually no interruption. Most modern fiber laser cutting machines incorporate an automatic nozzle changing system, so it’s easy to continue laser cutting for longer.
A nozzle changing system like the one pictured on this page holds 30 nozzles. The nozzle changer features an integrated camera that checks nozzle alignment, size and condition. Nozzles are automatically changed, and each nozzle is automatically cleaned after a preset number of piercings.
Most newer large-format fiber lasers also offer a bevel cutting option. This is a significant advantage when performing welding as a secondary process. Bevel cutting prepares the part for the subsequent welding operation. Because the fiber laser beam is guided directly to the cutting head via a glass fiber without the complex beam path and the several mirrors required by a CO2 laser, fiber laser is an optimal tool for high-accuracy, large-format bevel cutting.
Certain manufacturers, particularly those preparing structural parts for heavy-duty applications in industries like construction or shipbuilding, require that all surfaces to be welded are bevel cut. The bevel allows for a larger welding area, which improves the joining process and makes for a stronger weld. Most large-format fiber lasers are able to bevel or 2.5-D cut up to 45 degrees, cut shapes in pre-formed parts or cut under angle.
No tending needed
Often, large-format cutting machines require a dedicated operator to watch over the cutting process. This is especially true when plasma cutting to ensure that the curve width is consistent and for changeover of material or consumables. Fiber laser is by its nature a consistent and stable technology. Even when cutting in a large format, the fiber laser machine can operate without supervision and in a lights-out manner.
When cutting on a large-format machine, safety is a concern. Recent models of large-bed fiber laser cutting machines incorporate a higher level of protection for operation and maintenance. This includes multiple control panels situated at strategic points along the machine, collision-prevention 2-D scanners, an integrated fume exhaust system and scrap bins with fork pockets for easy removal by forklift.
While fiber lasers are known for requiring less maintenance than CO2 lasers, in many aspects, that is also the case when comparing fiber lasers to plasma cutting machines. A large-format fiber laser cutting machine is not as maintenance-intensive as a plasma cutting machine, considering the slats of a plasma table need to be changed out often, likely every other week. In contrast, the bed of a fiber laser cutting machine can last six months or longer, keeping overall cutting time high.
Today’s large-format fiber laser cutting machines also incorporate an exhaust mechanism to remove hazardous dust and fumes. Inadequate dust control can cause significant problems, which are amplified on a larger format machine. A large-format laser can include a 12-cartridge dust collector as part of the machine, which is twice the size of the standard dust collector that would be used on a 6-kW fiber laser cutting system.
The fiber laser continues to change the industrial laser landscape. Now with higher power capacity in large-format machines, fiber laser answers the need for large-plate cutting.
