One of the challenges in recent years has been how to get the best performance from a solid-state laser cutting machine without simply increasing the overall power of the engine. Increased power can lead to unexpected knock-on effects within the machine itself, such as increased consumable costs, as well as generally increasing the machine cost.
Several different beam shaping technologies have been developed by different manufactures, but these have all been static control solutions and all have led to the energy density of the laser beam to be compromised in some sort of way. Some even require additional optics to be manually changed by an operator in the cutting head before production can continue.
Research into dynamic beam oscillation methods and control systems revealed their ability to improve processing in the mid-range power band while keeping power consumption – and therefore cost-per-part – as low as possible, all while providing extra benefit to users. Amada’s R&D team discovered that significant improvements to the interaction of the laser beam and metal could be achieved by the ability to oscillate a low-order laser beam independent of the cutting head direction of travel, while maintaining the high brightness provided by continued developments in laser diode technology. This led to the development of Locus Beam Control (LBC) technology (see figure 1), which first debuted in 2018.
Figure 1: The difference between a standard solid-state laser without any type of beam control and LBC technology
Since then we have seen users increasingly realise that they do not require the high-power systems they initially thought they did, and that they can achieve similar cutting results using a 4kW LBC-enabled system – at lower running costs – than a 6kW system. Not only that, but they are also seeing that these systems require less regular maintenance than higher-power systems due to them being less susceptible to imperfections in the beam path, such as dirty laser optics.
Beam control beats power
When cutting thin materials, a standard solid-state laser beam has a sharp, power-dense profile. However, as the material thickness increases, the focus position must be adjusted to provide the optimum cut width to remove molten material, thereby reducing the power density of the beam. The only way to overcome this decreased power density and still provide enhanced cutting performance is to increase the laser power. With LBC technology, the power density of the laser beam never changes from the sharp, power-dense profile. The beam is moved dynamically in predefined patterns depending on the material and thickness being processed. This independent beam movement provides the optimum cut width, retains the high power density of the beam and allows material on the cutting front to be removed with high efficiency.
In order for users to take full advantage of this type of technology, Amada developed a new 4kW single diode module fibre laser engine. It was discovered during the development of LBC technology that keeping the low order properties of the laser beam was a fundamental requirement. Originally, in 2010, Amada developed a fibre laser engine using 600W modules that were combined together. In 2014 the design was changed to utilise 2kW modules. The elimination of combined modules meant the superior BPP of the beam was retained at the 2kW level. In 2017, 3kW single modules were introduced, moving this BPP benefit to a higher power level. Whilst developing LBC technology, a parallel development was made into a 4kW single diode module, as it was realised that the benefits of a high quality beam at higher power would provide additional benefits. When LBC technology was released on the Ventis-AJ fibre laser at EuroBlech 2018, it was therefore powered by the new 4kW single diode module engine without the need for a module combiner. It is this setup that users are finding capable of achieving similar results to higher-power 6kW systems at lower running costs.
The introduction of this type of laser processing also required the development of enhanced control systems in relation to the beam cutting direction. If the dynamic beam pattern is not altered during the cutting process, the final cut shape will not be as the customer requires. Vector Control technology was developed to eliminate this issue. Using this system, the dynamic beam pattern can be adjusted as the cutting head approaches, turns through and accelerates away from a corner, ensuring the required cut shape is correct after processing. Figure 2 shows three examples of instances where there is either no control or incorrect control (2a to 2c), versus the Vector Control technology result (2d). As can be seen, the dynamic beam pattern must be altered progressively in relation to the cutting head direction to ensure that the final cut profile is correct.
Figure 2: Three examples of instances where there is either no control or incorrect control (a to c), versus the Vector Control technology result (2d)
There are three main operating modes provided by LBC technology: Productivity Mode, Quality Mode and Kerf Control Mode.
In Productivity Mode, the cutting speeds achievable can be up to double that of a conventional 4kW solid-state laser. With aluminium, for example, the performance can be equivalent to that provided by an oscillator with 1.5 to 2 times the laser power. This extra performance also provides significant cost reductions. If we take stainless steel processing as an example, the costs can be reduced by about 50 per cent by that of a conventional 4kW solid-state laser.
Quality Mode has the ability to provide dross free stainless steel processing up to 15mm, dramatically reducing secondary operations.
Kerf Control Mode allows the cutting gap to be adjusted to suit the application. This ensures easier removal of parts from the cut sheet either by an automated part removal system or, in the case of thick parts, manually by the operator.
The combination of LBC technology, Vector Control technology and the 4kW single diode module fibre laser engine has allowed many users to increase their production capabilities whilst reducing running costs. For example, Omnis Mechanical in the UK initially planned to purchase a 3kW fibre laser, but when seeing the Ventis capabilities for compressed air cutting, which are the same as a 6kW fibre laser, they decided the Ventis offered more benefits for their production. Germany’s Funke Werkzeugbau and AMS have both benefited from the high cutting speed and quality in aluminium, which was found to be superior to 6kW fibre lasers available on the market. In addition, Somis, of Italy, has been particularly impressed with the dross free cutting capabilities when processing stainless steel with Quality Mode. Finally, Spanish firm Model Metal commented that no other laser on the market (even those with much higher power) could achieve the same cutting quality in 25mm mild steel as the Ventis with LBC technology.
Over 150 Ventis-AJ fiber lasers have been sold into the European market since the machine’s official launch in late 2019.
Takaaki Yamanashi is director and senior executive officer of the Sheet Metal Technology Development & Production HQ at Amada.