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Fiber Laser Extends Capabilities of Laser Welding Workstations

Fri, 04/30/2010 - 6:47am
Crafford-LaserStar Technologies Corp.

Crafford-LaserStar Technologies Corp., a worldwide supplier of laser microwelding, cutting, and marking workstations for industrial applications, premiered its first FiberStar laser welding workstation earlier this year, and is already examining other workstation products that feature fiber laser engines.

 

In recognition of the growing acceptance of fiber lasers for materials processing applications as a cost-effective alternative to conventional laser design, Crafford-LaserStar has added the FiberStar welding workstation it its product range. The new welding workstations provide a better quality output combined with improved process yield, reduced running costs, and lower maintenance demands, heralding a major breakthrough in welding performance.

 

Tougher Demands for Laser-based Manufacturing

For the typical laser materials processing applications, there is an almost universal requirement for consistently high quality results. For a large proportion of these applications, workstations that make use of conventional laser engines are more than satisfactory for the task.

 

Nonetheless, some industries are subject to particularly stringent quality requirements, particularly the manufacture of medical devices and electronics. Medical devices, implants, and components for the electronics industry often use 300-series stainless steel, with a wall thicknesses of 0.1 to 0.5mm. The specifications for the size, quality, durability, and performance of such welds are set very high. However, the weld process for such thin materials is actually very difficult, in that too much power can result in excessive penetration, which can lead to weak points and perforation. On the other hand, too little power can result in weak weld strength.

 

Crafford-LaserStar workstations find extensive use in low and high volume and high value assemblies, and precision assembly environments. They are capable of welding a wide variety of metals, and are highly valued for their low running costs and compact ergonomic design.

 

In order to provide the industry with a wider welding performance envelope, Crafford-LaserStar began exploring alternative laser engine options for a new line of workstation products with fiber laser specialist SPI Lasers plc (Southampton, UK). Over the last few years, and in close cooperation with strategic partners such as Crafford-LaserStar, SPI’s intensive R&D program has developed the fiber laser into a real-world industrial welding, cutting, and marking tool.

 

With more than 50 years combined experience in industrial manufacturing, applications specialists at Crafford-LaserStar are now confident that fiber lasers have matured beyond the performance window offered by conventional laser design, and are key to the next step in workstation performance.

 

New Performance Envelope

Crafford-LaserStar exhibited the new Model 7500 FiberStar workstation design at the MD&M West Show in February of this year. Designed for stringent welding and cutting applications, this workstation is equipped with an air-cooled, cw/modulated fiber laser from SPI and is the first fully integrated portable welding workstation of this type. Production versions of this workstation are available with 20, 50, 70, and 100W fiber lasers.

 

The new workstation has been designed with the needs of the precision microwelding and microcutting industry in mind, providing a level of accuracy and consistency previously unavailable. This is made possible by the unique capabilities of the fiber laser engine, including sub 0.5% pulse to pulse energy variation, +/-0.5% cw power stability over time, single-mode (TEM00) beam quality, and focused spot sizes down to 10micrometers. These features, coupled with high energy efficiency and no optical parts to align or calibrate, make fiber lasers an attractive laser engine for practical shop floor environments.

 

According to David Braman, VP of Engineering and Operations at Crafford-LaserStar, “full integration of the fiber laser into the FiberStar workstation provides full control over pulse energy, repetition rate and pulse duration for welding, with the workstation meeting all Class 1 safety regulations.” David also noted that the workstation has the ability to function in cw mode for cutting applications.

 

One of the biggest benefits is the improved overall system performance. The FiberStar can be guaranteed to perform to a higher standard for longer, and maintenance is simplified, allowing the end-user to focus his expertise on production. The new FiberStar workstation can be demonstrated in any one of the four Laserstar Centers operated by Crafford-LaserStar in the USA (in Rhode Island, California, Florida and Texas), and will be available internationally through established distribution channels in Europe, the Far East, and Australasia. Crafford-LaserStar can also provide on-site technical training.

 

Advantages of Fiber Lasers

Fiber lasers bring significant advantages to industrial applications. To begin with, they do not exhibit the shortcomings in output power variation, and spot size and focal point variations that are caused by thermal effects on the glass rods of traditional YAG lasers. Fiber lasers offer true welding consistency at all power levels, across all pulse sequences, and during the entire lifetime of the laser, the laser parameters remain predictable and consistent. The reason for this is that the generation and transport of the laser beam to the work-piece takes place entirely within the confines of a single-mode fiber. The beam shaping provided by this fiber neither degrades over time, nor changes with laser power. This also makes the laser exceptionally physically robust and stable, and thus suitable for the most challenging of industrial environments.

 

A further advantage is that the small spot size and high beam quality translate to high irradiance at the focus, so workstations equipped with fiber lasers can produce better results at lower power levels. The focused beam consistently affects a very small area of metal, with the benefit that very little heat is generated around the weld point. High quality precision welding can be performed close (0.1mm) to the most complicated and intricate component parts, but applications are not limited to just welding; cutting of medical grade steels and wire end preparation for medical components are both easily realized with the new workstation.<p>
From an economics standpoint, the consistent and improved welding performance means reduced scrap and faster production throughputs, coupled to lower operational running costs, and improved laser up-times. These financial and performance advantages mean that fiber laser technology is now frequently chosen as an upgrade over the conventional flash-lamp pumped solid state, or even DPSS laser technology in many other laser-based manufacturing segments. In addition, a small footprint and fast ROI open up markets that were previously out of reach for some applications.

 

Advantages for Industrial Manufacturing

David Braman states that the choice of SPI as supplier for the fiber lasers, in addition to their mutual long term partnership, is due to a number of reasons critical to performance in an industrial setting: “Firstly, the output delivery optic is back-reflection hardened, protecting the laser from potentially damaging reflections feeding back into the laser engine. Secondly, the pump laser diodes are also fiber-coupled to the laser and are rated with 400,000 hours MTTF (mean time to failure) giving a full system design life of 30,000 operational hours (on time). Both of these features help contribute to maximum up-time in the production process by guaranteeing maximum dependability.”

 

Additionally, high consistency of performance among fiber lasers of a given type means that the degree of repeatability between workstations is also much higher. For the end-user, this means setting up and maintaining multiple lines to produce identical high quality components has never been easier.

 

In general, the choice of workstation for any application comes down to determining the required performance, followed by a trade-off between initial outlay, component yield, uptime, and maintenance. While the initial outlay for the new workstation will be higher, David is confident that rapid ROI due to high yield, near 100% up-time and near-zero maintenance means that less demanding manufacturing processes can also benefit from the technology.

 

There is little doubt that the fiber laser engine offers distinct performance advantages, in particular the high level of weld quality provided over the entire working range and over the entire working lifetime of the workstation. Extra benefits to the end-user include a more flexible workstation with a broader performance window, and the ability for the end-user to focus on their business demands, rather than having to become laser maintenance experts.

 

In the longer term, as the market for fiber lasers matures, the specialists at Crafford-LaserStar expect to see more widespread adoption of the fiber laser engine for more general tasks. Likewise, as the performance window improves, we can expect to see greater diversification of workstation use, as well as penetration into new application areas, including marking.

 

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