Product category:
Laser-based systems
News Release from: GSI Group, Laser Division | Subject: Pulsed Nd:YAG lasers
Edited by the Manufacturingtalk Editorial
Team on 14 December 2006
High-power beams for micro-joining
The latest generation of GSI's JK pulsed Nd:YAG lasers provide precise, high-power beams that are ideal for micro-joining applications.
The latest generation of GSI's JK pulsed Nd:YAG lasers provide precise, high-power beams that are ideal for micro-joining applications The constant demand for increased performance and functionality is driving a trend towards ever smaller assemblies and components
This article was originally published on Manufacturingtalk on 18 Sep 2002 at 8.00am (UK)
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In the medical sector, for example, new treatments call for increasingly complex microsurgery tools and miniature implantable devices, while in the automotive, telecoms and electronics markets, the demand is to pack more power into a smaller and smaller footprint.
This is putting increasing pressure on conventional manufacturing methods.
In the area of micro-joining in particular there is a need for processes that can guarantee high-quality consistent welds without damaging delicate components - often at extremely high production rates.
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For many of these applications, the latest generation of pulsed Nd:YAG lasers provide the best, or indeed only, way to meet these needs.
The new JK lasers have extremely high-quality beams that can deliver higher powers through smaller diameter fibre optics.
Combined with a precise control of the shape and power of each pulse this means they can produce high-quality welds in minute devices, exotic materials and even dissimilar metals.
"People are starting to become more aware of what lasers can do at the micro scale, and the process window is much bigger than it used to be," says Mark Greenwood, Technical Director of GSI Group, Laser Division.
"Four or five years ago the smallest focus spot you could achieve was around 250 microns, and you just couldn't weld the extremely fine features that we are now talking about.
"With the JK125, for example, using a 150andmu;m fibre optic we can weld material down to 20andmu;m thick with a weld spot as small as 45andmu;m in diameter - and we can deliver average powers of 120W and peak powers of over 2kW.
This technology is twice as good as the previous generation, enabling you to do things now that just weren't possible before." To give an example from the medical sector, one of the most effective ways of treating certain cancers, such as cancer of the prostate, is to implant a capsule containing a radioactive source next to the tumour.
This technique, known as brachytherapy, allows controlled doses of radiation to be delivered to the cancer without damaging healthy tissue.
The capsules that hold the radioactive 'seed' are only a few millimetres long, less than a millimetre in diameter and have a wall thickness of less than 150 andmu;m.
The welds that join the capsule together need to produce a hermetic seal, with a smooth weld bead.
The capsules have a high intrinsic value and, as disposing of radioactive scrap creates its own problems, there must be no rejects.
Welding with a GSI JK pulsed Nd:YAG, delivered by fibre optic, and with a focused spot size as small as 45andmu;m and pulse-to-pulse stability better than 1%, meets all these requirements in an easily controlled, versatile process that can produce finely-controlled weld beads as narrow as 50andmu;m.
On fine mechanical parts, such as aneurism clamps, or implanted medical devices, excessive heat could cause burn-through of delicate materials or damge sensitive components, but, says Dr Greenwood, the JK's combination of high power, precise pulse control and small spot size means that the laser energy is delivered exactly where it is needed, with very low heat input to the surrounding area.
Each pulse can be programmed in up to 20 blocks, with each block as short as two milliseconds to produce the right energy profile for each weld.
This not only makes it easy to prevent overheating or cracking on delicate components, it also allows the successful welding of reflective materials and even dissimilar metals - such as titanium and memory alloys to stainless steel for medical applications.
"We are now routinely making welds that would have been considered impossible just a couple of years ago.
This rate of development means that many design and production engineers just aren't aware of what can now be done - there must be thousands of new applications for laser micro-welding just waiting to be found," says Mark Greenwood.
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