Use of laser technology

German manufacturers of lasers and laser equipment are world market and world technology leaders. The following gives on oversight of the key application fields. Photos have been attached for downloading.

Reasons for the success of the laser

The success story of the laser is based in the first instance on the great number of advantages that it offers compared with other manufacturing technologies, whether technical or business. The main arguments in favour of using a laser that ultimately leads to cost and time savings for the user are found in the simple automation, high flexibility, precision, enhanced productivity, and finally the innovative potential of this technology.

Ever higher automation levels and throughput rates on today's production lines require tools that meet these requirements, also under strict cost and quality aspects. Lasers are highly compact designs and, thanks to standardised and modern interfaces, can be integrated very easily in existing production plant. One other advantage is that lasers operate without contact - the laser process is subjected to virtually no wearing.

Yet the tool light is extremely flexible not only in matters of automation: configurable machining parameters mean that the most diverse materials of various thicknesses and geometries can be machined without appreciable delays. High process flexibility is achieved, for example, with the use of a laser that inside the one manufacturing station undertakes both cutting and welding tasks or labels even a batch size of one economically after a simple program change.

Also higher demands based on product trends like miniaturisation, individualisation, tracing, or quality enhancement are met by the laser: thanks to its extremely high precision, ultra small components can be manufactured with the minimum of heat input and maximised reproducibility. The smaller the components, the more the laser can show itself off to advantage.

In addition laser technology represents very high innovative potential: frequently the use of this technology leads to a considerable improvement in product properties and is the first essential step towards realising new products. Also innovative, more economical production methods are realised by the laser: for example, today's disc lasers can cut glass with such a high edge quality that the conventional polishing process no longer applies.

Last but not least, the laser's properties ensure productivity: large batch sizes and piece numbers can be realised to an extremely economical degree.

Enormous benefit to the user

The laser is used predominantly in machine construction, the automotive industry, and the manufacture of semiconductors and electronics. Yet also medical engineering, packaging technology, aerospace, and many other sectors utilise today the advantages of the laser. Whether medicine, research, instrumentation, or telecommunications, lasers have become an integral constituent of our lives and many things we use every day would not have been possible without them.

With its increasing deployment possibilities, demands placed on lasers are becoming more and more diverse. In order to do justice to the most varied of demands from industry, a likewise wide range of solutions is required from the direction of laser manufacturers. That which in small scale constitutes various parameter settings for individual lasers, with which their application can be adjusted to the specific material or workpiece, on a grander scale is the necessity to provide quite different laser types and technologies, in order to make possible a constantly increasing number of applications.

In the meantime the laser has become a kind of black box in machine construction. Initially used to join only simple, rotationally symmetric parts like the components of an automatic transmission, lasers in the automotive industry today machine whole bodies. Roof and door welds, 3D trims of hydroformed components, hardened door springs, or labelled controls in day and night designs are only a number of examples from the range of applications.

Laser labelling has long been established in the semiconductor and electronics industries: extremely high labelling rates of up to 1 200 characters per second can be realised. Yet also ultra small characters of 0.2 mm invisible to the naked eye belong to the standard. Not only the principal markets of laser machining, also a large number of other sectors have established the laser as a manufacturing tool.

For example medical engineering where the laser has created a wide range of applications. Ultra fine laser cutting of microtubes for the manufacture of stents and medical implants is today state of the art. Laser welding has conquered not only metals, but also plastics for a growing number of new applications in medical engineering. One example involves the welding of hearing aids: the tool light has a low heat input and so can be used for welds near sensitive electronic components and for invisible and therefore highly aesthetic joins.

Laser technology has also become indispensable in dental engineering as well: lasers used to weld crowns and bridgework is superseding the conventional soldering, whose use of additives poses biocompatibility problems.

Dominating field of application - laser cutting

Still the largest market, laser machine tools for flexible sheet working continued the trend towards higher machining speeds and greater automation. The range of customers here is very broad and extends from the job contractor to the internationally operating large-scale enterprise.

The trend towards higher laser performance is also continuing for laser cutting in flexible sheet metal processing. This continues to be the market with the highest turnover for laser systems. After the 5 kW laser performance class has already gained the highest market share for laser cutting systems, the 6 kW class is now also showing encouraging sales figures.

The additional performance can be transferred into 40 per cent higher cutting speeds. For the users the increased flexibility is the most important benefit derived from the added performance, because it allows both faster cutting speeds and cutting thicker sheets. Aluminium can be cut up to 15 mm and stainless steel up to 25 mm thickness. Furthermore, new cutting strategies, such as FlyCut with its flying positioning on the contour, lead to productivity increases. Besides axial-flow CO2 lasers, diffusion-cooled lasers are also used for cutting, especially in the low performance class between 2 and 3.5 kW. One important development can be seen in the flexible processing of tubes and sections for new low-cost and versatile design elements. We can expect that this field, as a complement to the field of flat sheet, will experience strong growth over the next few years.

Some examples for increasing automation are automation components for unattended shifts and the automated singling and withdrawal of workpieces.

The general advantages of processing various materials with lasers, such as reduced finishing work and follow-up processes or enhanced process quality serving to minimise materials, weights, and costs improve especially in times of crisis productivity and competitiveness.

Laser welding extends the sheet metal process chain

Laser welding is a major growth market in flexible sheet processing. The extension of the sheet metal process chain by laser welding offers enormous potential for productivity increases even with small to medium lot sizes. Advantages of laser welding are not just higher process speeds, but also high quality welds. Post-weld rework times are reduced considerably. With the availability of standardised systems technology, modularised clamping technology and catalogued process data, laser welding is now firmly establishing itself as an economical alternative to conventional joining methods.

Although 3D laser cutting continues to achieve the greatest volume for a single application, it has now considerably dropped to less than half of the sales achieved by CO² and solid-state lasers over 500 watts. One decisive reason is above all the laser welding market's development into a volume market. Laser welding methods are today qualified in all important sectors and many applications have been established for many years.

A particular positive development is still shown by the segments of welding and 3D cutting. In shipbuilding, for the first time up to 90 per cent of the steel used for a ship are welded by lasers - a total of about 200km of laser-welded seam. In aviation, too, the laser is finding increased application. Thus, the process of welding stringers already successfully introduced on the Airbus A318 is also being used on the new large-capacity Airbus A380 to save weight, costs and time. As compared with traditional riveting, laser-welded seams are also more stable and less susceptible to corrosion.

Important application fields for laser welding and 3D laser cutting are found in the automotive industry. An increasing number of laser sources in body shops and the manufacture of tailored blanks and hydroformed components over the last few years have promoted large growth in sales. We estimate the basis of German laser sources in these sectors worldwide to be as high as four figures. An equally large number of laser sources is installed in addition in plant for manufacturing e.g. transmission, clutches, airbags, fuel injection systems, exhaust systems, etc. At the same time, also the spectrum of applications keeps growing, especially in supplier plants. A great potential exists in world-wide laser use for car body production currently wide-spread especially in Europe. As a milestone in this respect laser-welding on the Audi aluminium body frames can be advanced.

Laser welding in car body manufacturing has received a new impetus through the technology of remote welding with a scanner. The study entitled "Tomorrow's automotive manufacturing", conducted by McKinsey together with the laboratory for machine tools of the university RWTH Aachen, which has been made available in excerpts, has examined the importance of remote welding for the automobile industry. The study has found that the use of remote laser welding can bring down investment costs by 30 per cent and reduce cycle times by 60 per cent. The required production area will be 50 per cent less. The study predicts that remote welding can reach a share of up to ten per cent of joining methods until 2015.

In remote welding a scanner mirror directs the laser beam to the working area from a distance of up to one metre. This reduces positioning times so much that they become almost negligible. However, an important precondition for remote welding are beam sources with high beam quality. So far, especially CO² lasers were used in stationary scanner systems.

Since the advent of highperforming disc lasers in 2005 there will be now also be solid body lasers available that meet the requirements of remote welding systems as to performance and quality. In conjunction with laser light cables and robots, disc lasers for three-dimensional tasks can be employed to create so-called "Robscan" or "scanner welding systems". The first ever use in serial production of Robscan was already carried out by DaimlerChrysler.

Moreover, the economic efficiency of solid-state laser applications is enhanced by so-called "laser networks', or the linking of different work stations to one or more laser sources for optimal laser utilisation. At the same time, these laser networks enhance the flexibility for users.

A specific example for laser machining in the automotive industry, as already mentioned by Mr Leibinger, is a new method for laser erosion of tailored blanks made from high-strength steel. Since high-strength steel deforms at temperatures of more than 900°C, components require a special coating as a protection from scaling and corrosion, which has to be removed in the area of the seam for welding to be achieved. This procedure is advantageous in two respects: the steel, which has a higher tensile strength than conventional steel, is then able to be used for high-temperature reshaped tailored blanks, which leads to reduced steel plate thicknesses and thus savings in both weight and fuel. Over and above this, productivity compared to normal sand-blasting methods can be considerably increased.

Generative methods with great potential

Other laser methods with great potential are the generative technologies. What has been state of the art in plastics for a long time under the name of Rapid Prototyping is now also offered for metallic materials by generative methods. Besides metal powder with sinter additives, original materials are now also used increasingly.

Workpieces can either be produced in a powder bed or they can be coated via build-up welding with a powder nozzle. In the toolroom there is a great interest in this technology, especially where the production of contour-near coolant bores is concerned. Interest is also high for the production of customised components such as medical implants. Build-up welding is also an interesting option for surface finishing or the modification of large work pieces. A very specialised application is the building up of abrasion-resistant coats on parts of oil-drilling rods which are exposed to heavy wear and tear.

Highest growth in laser inscription

The fastest-expanding market are beam sources and systems for laser inscription. In terms of unit numbers this is also the largest market. More and more users avail themselves of the flexible, durable and abrasion-resistant inscription with laser light, especially for quality assurance and product marking. Lasers can inscribe many different materials, ranging from metal to plastics, glass and ceramics, with different wavelengths, performances and maximum pulse rates depending on the work piece.

In laser marking, the trend for application of long-lived diode lasers as excitation sources cannot be overlooked, the market share of these advantageous marking lasers being considerable. In particular for the semi-conductor industry which usually operates in three shifts with high components turnout, determining arguments for application of the modern laser marking technology are maximum availability and high processing speeds.

Laser marking systems can be used not only for individual printing of SmartCards, for instance, but also for depositing Bitmap images in top quality. An interesting application also is interior marking of glass. Adapted beam sources can achieve sufficiently high intensities to produce extremely fine micro-fissures in the glass at any desired spot. Special software thus allows to produce three-diemensional representations and imagery in a minimum of time. However, marking lasers today are also used for producing small depressions in polished high-quality stoneware and natural stone floor tiles in order to increase stepping safety. Each square meter is provided with 3 or 5 million depressions which are not visible to the human eye, though.

The current drop in sales in the semiconductor and electronics industries has mainly affected the marking laser, which is used extensively to letter semiconductor devices, PCBs and SmartCards. The trend of minimizing size and weight as well as the lifely demand for flexible, permanent, and tamper-proof component lettering remains undiminished. In 2003 this segment once again showed a growth. For 2004 reliable sources prognotize a return to growth for these industries. One highly significant application is lettering that quality assurance can use to trace single components back to their source, e.g. in the automobile industry.

In an ever greater number traditional bar codes are being replaced with 2D matrix codes for the identification and traceability of components. Their considerably reduced surface requirements provide an essentially higher information density, and they are still machine-readable even when slightly damaged.

Laser micro-processing

Laser micro-technology is a field of highly dynamic growth, due to the trend for miniaturization in the area of electronics, semi-conductor production or medical technology. For producing a mobile telephone, for instance, more than a dozen different laser applications can be used for the reduction of weight and size. Micro-applications is the term for work demanding top precision on minute components. Typical applications include seam and point welds, surfacing, fine and ultra-fine cutting, notching, drilling, soldering, decomposing, engraving, trimming and perforating.

The system solutions cover the whole range from fully automated production plant to manual welding sites, with applications in automobile construction (for welding fuel injection nozzles), mould building (for engraving and repairing injection moulds), electronics (for welding battery boxes), and even medicine (for cutting coronary stents), the seal-welding of aluminium battery boxes or the welding of DRAMs for enhancing clock speeds and minimising surface requirements. The most diverse approaches can be taken for finding solutions and range from the deflection and distribution of lasers with optical fibres to fast beam positioning with galvanometer mirrors. These solutions can be used for marking applications, often in conjunction with camera systems for detecting the position of components and for precise corrections ot the laser path.

It is in particular the area of laser perforating that presents a high application potential. Thus, a special CO² laser and an adapted optical processing system can today be used for perforating 500 000 holes per second in moving paper of plastic webs. Applications include paper tips for cigarettes and plastic foils for packaging purposes.

Mentioned is here the simple opening of packaging along a defined line or the fact that air exchange is made possible without changing the moisture within wrapped goods. One should think of prolonged durability of food.

Important application areas fur ultra-fine laser cutting are semi-conductor production, micro-electronics and medical technology. Here, the high precision, the speed of processing, the small heat-affected area, the flexibility and the absence of wear of the laser as a tool in particular constitute positive aspects for its use.

Diode-pumped hogh-power lasers become established

Diode-pumped solid-state lasers with multi-kilowatt power outputs are becoming established on the market, yet market penetration is progressing more slowly than predicted. On the other hand, diode-pumped solid-state lasers of lower power output have been highly successful for many years on the labelling sector. Disc lasers with kilowatt outputs (a diode-pumped solid-state laser with disc-shaped crystal and particularly high laser quality) are now also on the market and are finding a large response within the applying industries.

Diode lasers for direct working have in the recent years gained a firm position in the laser beam source technology. More and more of these extremely compact and almost maintenance-free lasers are being used in industrial production for welding thin metal sheets, for hardening, soldering, and in plastics processing.

The possibility of welding plastics with lasers has given rise to a new field of activities that has successfully evolved. Air conditioning ducts of plastic for the rear seats of automobiles are being joined by laser, and laser-welded crash sensors transfer the lifesaving signal to the (laser-welded) detonator of the (laser-cut) airbag. Also minimum heat contribution, clean surfaces, and absolutely tight welding are the characteristic and promising features of laser welding.

Laser welding of plastics all colours

Laser welding of plastics has become a well-established form of joining technology in recent years. Besides its excellent weld quality - with almost the same firmness as the basic materials - other positive factors for this laser as compared with conventional methods are the low mechanical and heat exposure of the components and simple component structures.

Thanks to special laser transmission methods the colouring of the components plays a decisive role. Black or rather dark components are fairly easy to process with a laser, whereas bright or even transparent parts still pose a challenge for a laser welding process.

At the plastics trade fair K in October 2004, a joint venture of the BASF pigments department, masterbatcher Treffert and the laser manufacturer for the first time presented to the world a special type of laser additives - the Lumogenes IR - which now allow welding any combination of colours. In the NIR range, the maximum absorption of these lumogene dyes is about the same as an ordinary laser wavelength (808 nm). Moreover, residual absorption in the visible range is minimal so that these additives can be used for near-colour-neutral admixing. Apart from that the lumogene dyes fulfil all necessary conditions such as toxidity tests, light stability, migration stability, etc.

Welding of bright or transparent plastics parts is expected to find a ready market especially in medical technology, electronics and human care.

Laser Surfacing and Repair Welding showing Advantages

A promising application for lasers is in the manufacture of injection moulds as well as forming and blanking dies. These are subject to complex loads leading to deterioration caused by wear of corrosion and therefore have to be repaired, corrected or reworked frequently. The classical surfacing methods such as TIG, MIG, MAG or plasma welding can lead to warping or even cracking due to the high temperature input into the workpiece and in any case give rise to substantial rework. Also, conventional methods virtually do not allow working out fine structures. In laser surfacing and repair welding with filler material, heat input is minimal so that heat warping, structural changes within the base material, and rework requirements are minor. Distinct economic benefits result from a drastic reduction of processing time. Even filigree structures can be treated.

Laser eroding in mould making drastically reducing delivery times

Much potential for elaborating fine filigree structures, where milling becomes increasingly difficult and electric discharge machining often requires a great variety of electrodes, is also offered by laser eroding in the manufacture of injection moulds. The slogan of "rapid tooling' becomes reality: CAD data can be converted directly into processing programs, and even special materials such as carbid metals and ceramics can be worked efficiently. A mould which previously required more than 30 EDM electrodes and approximately 120 hours of work now is completed within 7 hours. For bigger moulds, a combination of milling and laser processing will be appropriate.

Engraving of Intaglio plates (steel engraving)

Together with the Austrian Bank Note and Safety Print GmbH (OEBS), a method has been developed for direct engraving of plates in Intaglio printmaking. This technology is an engraving method that combines the possibilities of stamping with those of printing. Up to now this method still involves rather elaborate etching. With laser engraving production times for plates can be reduced significantly. This method, which is far more environment-friendly than chemical etching, also allows incorporating additional safety features in the printing of security documents.

Surface cleaning by means of lasers

The basic principle of this is simple: an extremely short laser pulse of very high power hits the coat to be removed. The energy acting like an impact cannot be dissipated via heat conduction, but blasts the coat off the surface to be cleaned as if by an explosion. This method finds application today in a number of cleaning and coat-removing operations in various industrial areas. These include niche applications such as removing coats from brake lines as well as treating flat cables, cleaning moulds in the vulcanization or tyre industry, or cleaning of buildings and works of art.

Laser erosion alone offers a series of further deployment facilities, such as the non-damaging removal of paint layers in the aircraft industry.

MLBA glass-cutting

This new method allows cutting glass with yag laser sources. In this method, the laser beam is repeatedly passed through the glass substrate above and below the glass disc. This repeated traversing ultimately ensures that the entire laser energy is absorbed and will heat up the glass evenly across its entire thickness. The cutting edge has a smooth surface and in many applications will not require any additional finishing. The method is patented.

Recently, a series of impetuses have also emanated from Asia concerning new application areas. For example, a new one is laser cutting of glass for plasma displays (PDP), using solid-state lasers. This special procedure ensures extremely high-edge quality. Likewise, the surface structuring of plasma screens is frequently carried out by means of lasers. The consumer electronics sector generally offers high growth potential, since a laser is most likely to be involved in the manufacture of an iPod, MP3 player or a mobile phone. Most SD cards are cut using a laser and many mobile phone batteries are marked or welded by means of a laser.

Processing of solar cells

A further area of application with considerable potential is currently illustrated by the processing of solar cells. Not just since the publication of the climate protection report is solar cell production being massively pushed ahead both in Europe and in the USA and China. The application possibilities extend from cutting or plating through and right up to marking, laser milling or edge insulation and are generally achieved using low-power solid-state lasers.

Further special applications

As "proven records' cutting of SMD templates, welding of batteries and work in the jewellery industy.

These are just a few newer trends with regard to laser applications and further examples can be quoted at will. What is certain though is that the deployment possibilities for light as a tool are by no means exhausted. It is our task, along with providing as big a spectrum as possible of existing and new technologies, from system solutions plus applications expertise, and not just optimising already established applications, but also qualifying further innovative applications for the industry.