Laser cutting technology is no longer costly for mainstream sheetmetal fabrication due to rapid developments in speed, cutting quality and manufacturing. The laser beam is now efficient enough and has been quantified as a universal tool for cutting, welding, surface treatment and coating.
Not only does it enhance OH&S standards by operating silently and without wear and tear; laser cutting technology produces burr-free edges with narrow kerfs and minimal heat-effected zones. Its advantages include minimal heat input, low distortion and high feed rates.
Integrateability has been a key factor in laser cutters crossing into the realm of mainstream cost effectiveness. With the worldwide increase in versatility of turret punch presses, fabrication companies at all levels have greater possibilities to add laser cutting manufacturing solutions for their applications.
The company’s marketing director, Andrew Bentrup, said that now the integration of several work stages in the punching unit, the manufacturing of sophisticated components becomes possible at a lower cost/component ratio.
The share of ultra fast laser cutting systems, featuring linear drive technology is increasing due to fabricators’ demand for faster part processing time combined with enhanced accuracy and reduced setup times. Today, many manufacturers are looking closer at lasers to meet low run, high part number needs because of a disappearing need for higher volumes of the same part numbers and it is important to understand how the features of the present technology will last into the future.
Anticipating what the best features of a laser cutting system is important, but more vital is the evaluation of which features will become ‘obsolete’ and costly in the years to come. The basics of laser cutting have not changed for the past 20 years. There is an energy source (the laser) that removes material by thermally vaporising it. The mechanism to do this is controlled by five major elements: power, feed rate, focus, assist gas pressure, and type of assist gas.
Feed rate controls either the material or the laser movement at a speed that will allow the laser to consistently vaporise the material. Focus places intensity of the laser beam either on the surface, above, or into the material to achieve the desired cutting condition. The type of assist gas and pressure will remove the molten material and achieve the desired edge quality.
Recent Developments: According to Bentrup, high technology machine tools are what most manufacturers are looking for.
Lower set up times, high part quality and accuracy have been a natural benefit of laser cutting systems. Fast cycle times on lasers have always been related to geometry. Large radius parts cut on a laser have always outperformed other manufacturing methods.
With the latest in new linear drive technologies, the cycle time margin on traditional sheet metal systems is narrowing. A completely new type of laser design needs to be provided to accept the speed of acceleration that the new drive technology offers.
This new speed of process combined with the existing trend of the laser industry towards automation make the future of this manufacturing technology bright. Technologies like DpM and DpMplus are examples and make it easy to understand how fabricators can benefit from those new developments.
Control of axis movement has improved over the early systems, especially over stationary beam style lasers. Yet, most machine tool manufacturers still embrace either ball screw or rack and pinion drives.
Focus point is automatically changed through a cutting database or technology table. Assist gas change and pressure are system controlled as well. In fact, most of the internal functions of laser cutting have been automated. The NC cutting database has taken over almost all of the operational commands, leaving simple functions like nozzle or focus lens alignment or change to the operator.
Higher laser powers have advanced the technology as well. Thicker capacities of metals can now be processed, but the real advantage of higher power (3,000W and above) has been the increased feed rates on thin metals.
By using an inert gas, cutting speeds of metal are almost three times faster than earlier wattage systems. However, in efforts better to maximise speed of cutting more and more attention has been paid to nozzle design and beam collimation.
Punch-Laser Combination Machines: The development of laser cutting systems in recent years and the benefits associated with laser fabrication have increased interest in the use of laser cutting in many sectors of industry. Laser technology, in combination with punch press machines, has been used in the industry since 1980s.
Product designers are able to consider the opportunities of punch presses with the ‘four-in-one’ solutions, i.e. using forming, tapping, punching and laser cutting in one system to have different manufacturing methods available within one fabricating cell. However, various sheet metal components can be made using different machines, but also with one common manufacturing tool – laser cutting.
Manufacturing Benefits of Punch/Laser Combination: In recent years, machine tool builders have managed to economically integrate different manufacturing methods in a system through punch/laser combination systems. Fast axial flow CO2 lasers up to – 3,000 Watt laser power play the dominant role as an additional tool in the turret punch press. The integration of a diffusion cooled 2,500 Watt SLAB CO2 laser with its outstanding beam quality equals even 3,750 Watt laser power in comparison with conventional fast axial flow CO2 lasers. The heart of the machine is the robust O-frame of welded construction. The rigid construction of machine frame and the coordinate table permit the use of high axis speed and acceleration.
The punching operation can be generated either with a hydraulic system, with the possibility for more than 1,000 hits on 1mm axis movement, or by a servo-motor-driven mechanism. Its principle is made possible by a combination of electrical servo technology and mechanical power transmission.
Further enhancements also include linear drive motor technology allowing the punch/laser combination to become not only as fast as the 3-axis high speed laser systems but making the new combination machine the most universal sheet metal fabrication centre in the market, capable of punching, forming, contouring, marking, and tapping in one single set up without releasing the sheet metal fro the work holder.
More Integrated Work Stages – More Automation: Besides punching, nibbling, forming, marking, even bending and tapping operations are possible. For outside part contouring and special inner contours, in order to avoid nibbling marks, sharp edges or buying special tools the laser is used to increase part quality in one operation with no additional material handling.
Additional increases of productivity for punch laser systems are modular extensions in the overall system, like loading/unloading, part sorting or stacking.
The laser cut parts will be guided outside the working area via trap doors and conveyor systems. From this point or even straight from the cutting position a sorting and stacking robot transfers the part to its programmed sorting address.
High-Speed Laser Cutting Systems:
Flat bed laser cutting systems have been established technology in the sheet metal industry for more than a decade. The flexibility of the laser cutting process in producing components with various contours, with varying thickness and materials, has led to the world-wide use of these systems.
High speed laser cutting has been accepted by sheet metal manufacturing shops throughout the years as several studies of institutes have shown the possibility of cutting materials such as 1mm aluminium at 50 m/min or even faster.
Many sheet metal applications have been solved with punch presses due to manufacturing costs for the component. With the integration of linear drive technology, new and rigid machines had to be developed to achieve positioning speed up to 300 m/min and acceleration of more than 20 m/s2. In addition to this, the laser cutting speed could be set up to 25 m/min for 1mm mild steel without a negative influence to path accuracy. In aluminium even 50m/min cutting speed is a standard parameter in the system cutting data base.
The high-speed laser cutting system can be designed also for flexibility. With the use of, for example, 4,000 Watt laser power mild steel can be cut up to 25mm.
Higher cutting speed for thin material and the repositioning speed from one cutting point to the next contour have led to higher productivity in comparison with conventional flat bed laser cutting systems.
The laser cutting process is a complex one, which is why a more sophisticated and user-friendly operator interface for the CNC control was developed for the system. All necessary parameters are available, and functions from the system can be activated through a Windows-based touch screen operator panel.
The process time for a complete sheet has been drastically reduced. Also more and more material handling devices like loading and unloading from the sheet are installed in high-speed laser cutting systems.
A further step towards more sophisticated material and component handling is Finn-Power’s laser cutting centre LC6. This automation for laser cut components helps the customer integrate laser operation and part handling for fabricating high-quality components within one system.
The LC6 Laser Centre utilises a fixed laser beam system, combining the unique C-series turret punch press drive concept with the latest generation of diffusion cooled CO2 SLAB laser.
Laser Automation: The biggest trend towards laser cutting over the last 10 years has been one towards automation. This trend promises to continue. The reasons are varied and this trend promises to continue.
Bentrup says that the consistency of operation of an automated cell, especially with a laser at the heart of it, offers complete flexibility to the manufacturer. Reaction time to the customer’s demands is minimal.
There is no costly tooling inventory to manage, nor need pallets be chased down to be prepared for processing.
More and more companies are implementing lean manufacturing strategies to minimise wasted movement and overproduction of parts and thus reducing inventories. An automated laser cell is the suitable tool to achieve these goals.
Developments in laser power control and technology tables have reduced cycle time and set up. The new developments in linear drive technology are causing manufacturers to rethink the basic design of laser cutting equipment.
Laser automation and the new advancements in laser processing are likely to bring the production cost-per-part lower than ever before, with less set up and higher throughput.
The future of any technology depends on how that technology best serves its end user, the customer. With this thought in mind, the future of the laser technology is moving in the right direction.