The application of laser technology is pacing the demands from the electronic, medical and aerospace with increasingly tighter specifications. An example of this can be found in machining circuit paths for electronics that must be 10μ with a tolerance of 1μ. The process must be performed quickly, and with depth of cut control that does not affect the substrate beneath the circuit path.
A short pulse laser, called Staccato, by RPMC Lasers is finding acceptance in machining fine features in a variety of materials. For micro-machining applications, the fundamental wavelength of this laser unit is 1μ. It delivers 13ps long, diffraction limited pulses at a peak power rating as high as 38MW, according to the company. A single pulse from the laser removes materials as thin as 1nm and as thick as 1μ, depending on the material being cut.
A technological advance of this new laser is its ability to generate peak power at 100kHz that's 100,000PPS. This translates into a significant improvement in the amount of material that can be removed.
Owing to its short pulse and rapid frequency, the heat affected zone usually associated with longer frequency laser pulses is reduced or eliminated. At the ultra-high frequency of the Staccato, material is blasted from the cutting zone and does not have time to recast on the workpiece surface. The result is a smooth and accurate cut at relatively high-production rates.
This new laser system is designed for use on the factory floor. It is not a laboratory machine. It works well in a manufacturing, shop floor environment.
The laser is designed to be an augment to conventional laser machining. It is not designed to replace conventional lasers but, rather, to offer manufacturers a tool to make cuts that are currently beyond conventional laser technology.
CO2 laser-cutting systems
High-power CO2 laser-cutting systems, while suitable for cutting thick metal plates, often fall short when it comes to cutting thin sheet metal. That's because these lasers generally can't run at full power or speed without damaging thin material. However, a new class of low-cost, compact laser-machining stations, built around a sealed CO2 laser and machining centre platform, promises to process thin sheet metal parts more efficiently and economically than their massive counterparts.
For the most part, shops must reduce power more than 50% to cut thin material with a high-power laser-cutting system. Doing so, minimises dross, re-cast molten metal. Running at reduced power is also important when cutting around corners because the metal on each side of the laser focal spot is in the heat-affected zone (HAZ) and easily melts when the laser beam moves into this preheated region.
To avoid overshoot, the cutting speed of high-power CO2 lasers is usually limited to approximately 100 inch/min, although the machines can cut thin sheets up to 30% rate. Unfortunately, shops won't get a maximum return-on-investment by operating these high-power lasers at less than 50% power and at only 3% of their maximum cutting speed.
Sealed CO2 systems, on the other hand, are built around a lower average power, below 500W. These systems complement high-power systems by processing thin sheet metal more economically, leaving high-power systems free to efficiently cut thick metal plates. This makes them perfect for laser job shops specialising in high-precision fabrication of components and the processing of exotic materials.
Laser cutting needed an inexpensive system that was easy-to-use and versatile enough to tackle drilling, engraving, and welding. The laser also had to meet customer requirements for ever-tightening levels of dimensional control, finer features, better quality, and greater cleanliness of finished products fabricated from thin sheet metal and thin-walled tubing.
Sealed CO2 lasers have qualities that make them well suited for thin sheet metal processing. They feature slab-discharge technology and offer the benefits of compact design, ease-of-use, maintenance-free operation, and low operating costs. Laser heads can also operate up to 25,000hr without needing scheduled maintenance. This translates to over 21/2 years of continuous operation. Two further advantages of sealed lasers are their fast pulsing, up to 100kHz, and high peak-power qualities of 1.5 kW/pulse.
The slab-discharge technology used in these lasers produces high frequency pulses with extremely fast rise-and-fall times relative to the duration of the pulse. Therefore, metal is efficiently cut or drilled rather than merely heated. The result is a clean cut or hole with little heat induced damage. This efficiency, coupled with fast pulsing, allows slab lasers to process metals quickly.
In addition to their other benefits, compact laser-machining systems won't blow a shop's budget. For example, a laser-machining station using a 500W sealed laser, and with 4th-axis capability for radial cutting, costs less than $200,000. An additional 5th-axis option can also be added to a machine later, if necessary.
Growing market needs
High-strength steels, gaining popularity because they reduce vehicle weight while maintaining structural integrity, present challenges for a blanking press line. With their high yield and tensile strengths, these metals require high tonnages, larger presses, and frequent die maintenance, because the cutting die's blades can dull quickly. Quality issues also arise with mechanically cut edges in this material. As material hardness increases, so does the propensity of micro-fractures after the blanking die shears the metal. Even worse is the potential for micro-cracks to develop into major fatigue-failure splits while the panel is in use on a vehicle.
"Laser technology is pacing the demands from the electronic, medical and aerospace with increasingly tighter specifications."
In these cases and others, laser blanking can provide an advantage. Using lasers eliminates the need for the blanking die that, depending on its complexity, can cost about $100,000 initially, with annual maintenance costs about 25% of the initial purchase price. Lasers also eliminate a press foundation pit, and certain laser blanking configurations eliminate the coil-looping retardation pit. The laser blanking setup also requires a smaller crane capacity for coil handling. No blanking dies also means no die storage or rolling-bolster die change areas and, of course, no die changes.
Lasers make blank development and nesting more flexible. Any change requires altering the laser cutting CNC software program, not a new blanking die. While a blanking press line prefers shorter progressions at high-press SPMs and a high-speed stacker, laser blanking prefers long progressions with a flexible stacker capable of handling multiple parts at a time. Producing blanks for draw-die tryout in forming presses is also easier. The laser blanking line can produce several stacks of parts and make small modifications to the blank size during draw- die tryout.
Today, a single-head laser system is less expensive than a blanking press capable of producing blanks up to 13ft long from coils up to 9.2ft wide, though certain simple, single-laser systems may not achieve the throughput of traditional press blanking lines. For increased throughput, a laser blanking line is designed with multiple laser heads in a series or in parallel for a single coil line.(finished)
