March 2009Issue No 8
Mike Barrett, AILU Laser Safety Representative
Health and Safety is a major factor in our business lives. For industrial users of laser machines the Provision of Work Equipment Regulations and the Supply of Machinery (Safety) Regulations apply and though they only make a small reference to lasers themselves, they establish the principle of risk assessment and together with related standards, give guidance relating to the control measures to be put into place to eliminate or minimize the residual risks.
Compared to other industries, the laser industry has an impressive record for safety. International standards advocating necessary safety measures to be taken were published less than 4 years after the initial practical demonstration of the laser and these standards are still being developed to keep abreast of the challenging advances in laser technology.
Later this month the International Laser Safety Conference (ILSC) organised by the Laser Institute of America will be held in Reno, Nevada, drawing together members of the international laser safety community over a four-day period to address all aspects of laser safety practice and hazard control. Technical sessions and workshops will address developments in regulatory, mandatory and voluntary safety standards for laser products and for laser use. For laser safety professionals the event presents a valuable opportunity to meet, network and discuss research programs and standards.
As AILU’s representative on the British standards Institute Committee TC76, which deals with standards relating to the safety of lasers, I will also be involved in several Working Groups of the International Standards Body IEC/TC76, who will be convening in Reno to review current standards development work. The programme is a busy one leaving little time for the pleasures in life, but someone has got to do it!
Mike Barrett
 Job Shop Group Chairman’s Report- Spring 09
Welcome to the JSG report for the electronic newsletter. Although our machines are not as busy as last year I seem to have spent more time with marketing our laser cutting services than ever before to try and get some enthusiasm from our customers. At our JSG committee meeting last week our JSG members had quite a large variation in the amount of work available for their machines. Some job shops have had to resort to short time for their employees, other job shops in specialist markets have not seen a down-turn. At our job shop we suddenly in the middle of February fell off the proverbial cliff, we have had small busy spells in the last 4 weeks but generally we are keeping our costs down and our marketing up.
For the last few years the AILU job shop group has been running a deal with laser machine suppliers whereby purchasers of laser machines who are not AILU members effectively receive a year’s free membership. However, being free, these members have a tendency to undervalue their membership, failing to take advantage of the many benefits that membership brings. The Job Shop Group within AILU held a committee meeting recently and I’m able to report that its customer services team is on the case! Committee members have agreed to a mentoring scheme to encourage participation in the on-line forums, surveys and other membership activities.
Feed-back from the first year free members has been slightly negative, however, I personally do not believe we need a drastic change in the content, just tweaking and good quality feedback. AILU covers a wide spectrum of interests, and if the magazine was full of gas surveys and CO2 lasers cutting 15mm stainless steel then the academics amongst us might start moaning about the magazine content and anyway, in 10 years time we might all be asking ‘what’s a CO2 laser?’ If you do not read the techy bits how can you keep one step ahead of the pack?
As our job shop machines get bigger, quicker and more powerful we never seem to run out of new ideas and applications to fill their ever increasing thirst for work. Of all the modern production techniques, the laser process still manages to grow strongly despite economic downturns, we might have some major hiccups currently, but I fully expect those job shops who are members of AILU to still be there when the economy gets back to full strength.
Dave Connaway
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Magazine Articles
The articles below are from the Winter 2008 Issue of the AILU Magazine
Profile and microstructure control in direct deposition
In laser cladding the energy of a laser beam fuses a material addition to the surface of a component; a different material to alter the surface properties of the part, or a similar material to enable repair of wear or damage. Residual stresses during solidification, brought about by thermal gradients in the molten deposition pool, can result in cracking in the clad material; high temperature at the centre of the melt pool and uneven cooling rates can result in undesirable variations in grain structure across the clad surface, mirrored in variations in strength, fracture toughness and corrosion resistance.
Laser clad tracks deposits typically exhibit a domed profile. A number of factors are believed to influence this shape including the mass flow profile of injected powder and the time a discrete section of the melt pool surface is above melt temperature. Mass transport effects, caused by stirring of the melt pool, also contribute. By controlling the temperature gradient in the melt pool, which is the source of the currents, a more desirable deposition profile can be achieved, reducing the doming of the clad tracks and by so doing reducing the degree of overlap between adjacent tracks needed to achieve a uniform deposition.
The shape and intensity distribution of a laser beam play a key role in controlling temperature profiles. For example, if a CW laser beam with a circularly symmetric cross section were scanned in a line across a surface it would deposit more energy along the centre line of the scan even if the intensity distribution was uniform. In order to properly address temperature gradient effects a means of tailoring the intensity distribution and shape of a laser beam is required. Diffractive Optical Elements (DOE) provide this means.
Matt Gibson, John Tyrer and Rebecca Higginson
Loughborough University
IMAGE: A Diffractive Optical Element (DOE)
AILU members can log in to the AILU web site and download this article free of charge. Otherwise click here to order a copy’
Bond formation in laser and resistance spot welding
Laser and resistance welding often compete for the same spot welding application and choosing between the two requires careful analysis since they have many similarities including the ability to weld dissimilar materials, and join practically all types of metals and alloys. On the other hand, they have differences such as location of heat generation, part geometry, and weld metallurgy that affects bond formation and consequently the weld performance. Here we compare and contrast bond formation at the weld interface for laser and resistance welding and its effect on related factors such as part design and materials selection.
In resistance welding, the welding energy is supplied by electrical current flowing through the two welding electrodes, which also provide the welding force to hold together the surfaces to be welded. In laser welding, the energy required is supplied by the absorption of a laser beam. As well as energy delivery there are a lot of interesting similarities and differences between the two processes in terms of heat generation, shielding gas and type of bond. These issues need to be well understood before one can select between the two processes for a particular application.
Resistance and laser welding provide some unique options for the engineer when selecting a suitable process for spot welding. Even though they have many features in common including the ability to weld almost all metals, to produce spot welds, and to weld dissimilar materials, the two processes also have some interesting differences. An exposed weld pool provides additional challenges for laser welding, but the non-contact nature of the process provides opportunities too. Both processes can produce solder/braze and fusion bonds, but only resistance welding can produce solid-state bonds, a powerful process for bonding dissimilar materials. An engineer choosing between the two processes has to be aware of all the factors involved before making a selection.
Girish Kelkar and Neil Ball
IMAGE: Photomicrographs of sections of the bond holding a Niobium wire in the V-groove of a Kovar lead frame: (top) Laser and (bottom) resistance weld. The frame melts, and flows around the wire, forming a braze on the higher melting point component.
AILU members can log in to the AILU web site and download this article free of charge. Otherwise click here to order a copy’
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Forthcoming Events
25-26 March 2009
Medtec_09
Medtec is the Exhibition and Conference of Manufacturing and Automation Technology, Materials and Outsourced Expertise for Medical Device Manufacturers based in the UK.
26 March 2009
AILU workshop: Additive layer manufacturing: laser techniques and opportunities
The increasing current interest in the industrial uptake of laser additive manufacturing processes (cladding, sintering and rapid manufacturing) makes the biannual AILU workshop of particular interest to the laser community. Its scope includes both the laser-assisted additive processes and the related technologies, including laser sources, materials and CAD/CAM workpiece control. Applications include repair & refurbishment, rapid prototyping and tooling, low-volume manufacturing, and tailored surfaces (for improved wear/corrosion resistance). SEE IMPORTANT SECURITY REQUIREMENTS
23 April 2009
Photonics and Microsystems in High Value Manufacturing
This 1 day conference brings together some of the leaders from the UK and Europe in developing photonic and micro-systems for a wide range of high value manufacturing fields. The event is hosted by the James Watt Institute for High Value Manufacture at Heriot watt University in Edinburgh.
13 May 2009
Laser Processing for Plastic Electronics
This seminar provides the opportunity for companies and academics working in the Plastic/Printed Electronics arena to hear first hand the plethora of processes and applications that are enabled by laser processing techniques.
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Most Gorgeous Part
This wonderful example of 3-D laser marking of a glass perfume bottle was supplied by Charles Dean of Fimark Ltd. It is an example of what can be achieved by combining a galvo marking laser, a six-axis robot and a 3-D laser scanner.
In this example the bottle has a conical shape so wrapping the image over the surface is in itself a great challenge, made all the worse by the variations in shape of the body surface arising during the glass blowing process. The laser beam path is adjusted to the real part geometry, rather than a theoretical one. This also allows the robot to pick up the part in any orientation. The result is the fishnet design laser etched onto the bottle surface with no wrapping errors or overlap of the image.
A video of the process in action can be seen on the home page of the Fimark web site at www.fimark.co.uk. Further examples are given on the '6-Axis Laser Systems' page of the site.
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Laser User Groups
Check out the activities of each of our special laser user groups within the Association. Our Special Interest Groups are where like-minded members can get together to discuss recent developments in their field.
Job Shop Group
Subcontract laser-based engineering companies form this group. For more details about their activities, see here.
Market Development Group
 The successful launch of the Design for Laser Manufacture site took place in September 2007, see here. To add your own information, images and videos please contact us.
Medical Group
 The Medical Group was launched in 2007. To join the group and influence its development, please contact the AILU Office. We are always keen to hear from you. For more details see here.
Micro:Nano Group
 The Micro:Nano Group activities were launched at the 10th Microprocessing workshop in June 2008. For more details see here.
Products & Process Innovation
 The aim of the Products and Process Innovation Group is to provide a focus for universities and other organisations involved in laser and/or laser materials processing development and/or research, to identify their common needs and create the possibility of joint initiatives and activities with industrial laser users. For more details see here.
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The Association
 The Association of Laser Users (AILU) was established in 1995 as an independent, non-profit making organisation run by and for laser users involved in activities such as manufacturing, healthcare, academic and industrial research; as well as suppliers of laser-related products and services.
The aims and objectives of the Association are set out in its Memorandum and Articles of Association. They include the fostering of co-operation and collaboration and the dissemination of information, experience and expertise relating to industrial laser technology, laser materials processing; its applications and related technologies.
AILU is a partner in the Photonics Knowledge Transfer Network, leading development in high power lasers and photonics. Contact the AILU Office for more information about the PKTN.
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Contact us
If you would like to advertise in the monthly newsletter, please contact us at:
AILU
Oxford House,
100 Ock Street
Abingdon
Oxfordshire
OX14 5DH
United Kingdom
info@ailu.org.uk
www.ailu.org.uk
Tel: +44 (0) 1235 539595
Fax: +44 (0) 1235 550499
Please note that this email is sent from an email address that cannot receive emails. Please contact us here.
If you would like other people to see this e-newsletter, please send them the following link www.ailu.org.uk.
If you would like to advertise in the monthly newsletter, please contact the AILU Office by email in the first instance.
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