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EVOLUTION OF LASER CUTTING TECHNOLOGY Defining beam shaping in laser cutting

Jul 28, 2022

The application story explains the usage of S7 Variable Beam Parameter Product (V-BPP) offered by Mazak. With this, the article highlights the evolution of laser cutting technology and illustrates the difference between a standard fibre and V-BPP fibre.

Laser cutting technology, like most modern technology, is constantly advancing. From CO2 lasers to fibre lasers, to advanced cutting heads with beam diameter control, and now generators that perform beam shaping. The next development in laser cutting is here.

Laser cutting technology evolution

When laser cutting technology was first introduced for fabrication, in the 1980’s, CO2 was the only option. By the early 2000’s, laser manufacturers started to evolve the laser source and fibre laser technology began.

Fibre lasers gave fabricators increased cutting speed, especially in thin gauge material. Fibre lasers also helped the bottom line with a reduced cost for consumables and energy consumption.

The next laser cutting advancement was high power lasers. Before 2015, the standard configurations for laser cutting machines were 2kW and 4kW. By 2015, high power lasers hit the centre stage. High power lasers offered fabricators the ability to cut at high speeds with a reduced bottom line in a greater range of material thickness.

While the thin gauge material was covered, many job shops cut more than just that. Often, these fabricators cut a large range of materials up to thick plate. This expansive range of material meant that thick plate cutting needed to be accomplished on the same fibre laser as thin gauge.

Offering edge quality

By 2018, 6kW became the new standard for laser cutting and the introduction to 8kW, 10kW, and 12kW started. The increased power not only gave fabricators an increased material cutting range, but it also offered improved edge quality through advanced cutting head technology. Right around the corner was high power lasers.

Initially, fibre laser cutting heads only used one lens with one focal length. Advanced cutting head technology changed that. Now many fibre lasers have sophisticated cutting heads with multi-lens, automated focus, and beam diameter control. This advanced cutting head functionality allows fabricators to process almost any material of almost any thickness on a single fibre laser.

While the combination of high-power fibre lasers and sophisticated cutting heads have an increased edge quality, it still is not the CO2 quality that many fabricators were striving for, until now. V-BPP, also known as beam shaping, now offers unrivalled edge quality with the fibre laser speed, low maintenance and reduce bottom line advantages.

What is V-BPP?

V-BPP stands for Variable Beam Parameter Product, often referred to as beam shaping. V-BPP offers beam shaping technology that comes directly from the generator rather than having to make beam diameter and shape changes in the laser cutting head. V-BPP is a way to command to the generator from the CNC a variety of shapes, sizes and power distributions that can be used for different cutting techniques and applications.

V-BPP can start with a very small diameter beam with the heat profile directly centre to that beam. This shape is often referred to as fibre mode. But the beam can get wide and create a ‘donut-shape’ mode. While V-BPP alters and changes the beam diameter, it is also altering the shape of the beam, where the power density is concentrated, and where the heat resides in the total spectrum of the beam profile.

Fibre cable delivery

From inside, the generator and proprietary beam types are created. But from there, that beam type is delivered through a fibre optic cable. With this next level V-BPP technology, a standard fibre cable cannot transfer these beams effectively. Now Mazak has paired both, a new generator technology and a new multi-core fibre cable for the OPTIPLEX NEXUS FIBRE S7. This new multi-core fibre cable has an inner core and an outer ring core.

By having a dual fibre core, it directs power to both the centre core and the outer ring core allowing for a balance in power distribution. In doing so, the power can switch from the centre core for rapid piercing through heavy plate, then switch and balance out that power to the outer ring core and reduce the power in the centre ring core. This gives a wider kerf width but maintains the heat profile needed to get through heavy plate. By doing so, it gives an advantage in thick plate cutting in edge quality, straightness of cut and speed of cut.

Standard fibre vs V-BPP fibre

For applications of thin stainless steel, thin mild steel or thin aluminium, a smaller beam diameter with a higher power density in the centre core is ideal, fibre mode. But for thick, heavy material it is necessary to have the beam
substantially larger in diameter. An example, 1-inch mild steel cutting with oxygen.

A traditional fibre laser, the beam directed out of the laser is a fixed diameter, while the beam diameter can be increased through cutting head technology, it is not possible to change the heat profile of the beam. A standard fibre laser going from 0.250” to 0.500” to 0.750” it is still using the same type of parameter product out of the generator because that is all that is possible, just one fixed beam type.

With V-BPP users command to the generator not only a different size diameter of beam, but also where the heat resides in the total spectrum of the beam profile. For 0.250” mild steel utilising V-BPP, all the heat is directed to the centre core of the beam and the diameter is rather small. When climbing to a thicker material, the beam diameter is increasing along with a changing heat profile.

Comparing standard fibre to V-BPP, even with a standard fibre increasing its beam diameter, there will still be heavy striation and the speed is limited due to the diameter of the beam. With V-BPP, using a much larger diameter and the heat not in the centre core but on the outer edges of the beam, gives a much smoother edge, a straighter edge and faster speed.

From left to right: 0.375” stainless steel with high performance air, 1.000” mild steel with oxygen, 0.188” aluminium with high performance air, 0.375” mild steel with oxygen, 0.750” mild steel with oxygen, and 0.625” aluminium with high performance air.

Choosing the right solution

Since advanced cutting head technology started, there is slang regularly used which causes confusion. Much of this confusion is around beam diameter control, mode and beam shaping.

Beam diameter control is not changing the mode and is not beam shaping. Mode is both the thermal characteristics of the beam and the three-dimensional shape. The mode is not focal length change. Focal length is just changing the convergent point of the beam. This is not beam shaping.

True mode changing is different, it is changing the shape of the beam and the heat profile in the beam. With standard fibre lasers, whatever comes out of the generator, it is. It is not changing beams in the generator. It is not different shapes.

Moving ahead with a unique solution

One question that may be asked with the introduction of V-BPP is, are advanced cutting heads technology of the past? The answer is a hard no. There are even more advantages to beam shaping technology when combined with an advanced cutting head.

Overall, V-BPP is much different than a standard fibre laser. V-BPP provides a variety of beam shapes, sizes and power distributions that can be used for different cutting techniques and applications.

Courtesy: Mazak Optonics Corporation

Image Gallery

  • Changes in power distribution

  • A diagram showing the S7 beam shaping quality advantages

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