Veli Kujanpää
The first high-power laser installation in Finland was a flat laser cutting system at Tammerneon Oy (Tampere) in 1981. Soon after, about ten similar systems were bought for sheet metal cutting. In 1985 a large national laser research project, which was the pioneering work on laser welding and surface treatment in Finland, was started and led by Lappeenranta University of Technology. Since then a rapid growth of laser processing systems has continued and it shows no signs of slowing down. The total number of systems in place is about 350 CO2 lasers and 130 Nd:YAG lasers, used mainly for cutting and marking. Recently seven diode lasers and a few fiber lasers have been installed.
A major portion of Finnish industrial laser activity is in laser cutting, with a minor role for laser welding. The main reason for this is the strong role of the heavy metal industry, where companies process in small lot numbers. Finland does not have companies with long production runs such as the auto industry, where laser welding was typically first applied in many countries.
The heavy metal industry was started because Finland needed to pay back World War II reparations to the Soviet Union so they agreed to pay with heavy metal products. So many large companies were established to produce heavy machines, lorries, trains, and so on. The last portion of these reparations was paid in late 1950s, but the industry remained and started to produce all kinds of heavy metal products such as pulp and paper machines, luxury ships, cranes, elevators, and power stations.
In the late 1990s the number of laser welding applications started to grow. Many subcontractors established facilities such as HT Lasertekniikka Oy (Keuruu), High Metals Production Oy (Vantaa), Laserle Oy (Vantaa), and LaserPlus Oy (Riihmäki) and applied it in several cases. Veslatec Oy (Vaasa) is a subcontractor in fine mechanics offering precision and micro-welding, as well as cutting and drilling, mainly using Nd:YAG pulsed laser technology.
Some companies apply laser welding to their own products. Outokumpu Oyj (Tornio) has two laser welding systems. One is in the company’s RAP sheet processing line, welding coils together, and another is in its Outokumpu Stainless Tubular Products Oy (Pietarsaari) plant for welding tubing. Ecocat Oy (Vihtavuori) welds catalytic converters using a diode laser (see Figure 1). Kennotech Oy laser welds sandwich panels in a new factory in Hämeenlinna. The most recent investment published is by Aker Finnyards Oy (Turku), for a sheet line that will use a 6kW fiber laser in a hybrid welding application.
Laser cladding is a subcontracting business at Kokkola LCC (Kokkola). Here the work is concentrated on repair welding for power station applications, but the applications are widening into other sectors.
One of the most specific Finnish applications is from Proventia Automation Oy (Forssa), which cuts television monitors for waste purposes (see Figure 2). This company, which was featured in ILS (September 2005), has a world-wide patent and produces the machines for cutting a more valuable face surface apart from the lead-containing tube.
Apart from laser welding and surface treatment, laser cutting is still increasing the business of subcontractors. About 200 systems for laser cutting are working for this purpose, and the largest company is HT Lasertekniikka Oy with more than 10 locations and 20 systems.
Research and education on laser materials processing is concentrated in two universities, Lappeenranta and Tampere Universities of Technology. At Lappeenranta Laser Processing Centre, which is a cooperative facility with Lappeenranta University of Technology and VTT, a national research center, there are 30 people working in R&D and education. The main research fields are in laser and hybrid welding, surface treatment, laser welding of plastics, laser microprocessing, and paper processing. The group is very active in publishing and servicing the industry. In addition, the university has undergraduate and graduate student programs in laser processing and arranges continuing education programs and seminars. In Tampere, 10 people are working on laser processing, concentrating on surface heat treatment. Tampere is also strong in optics and has several optics companies started from its Optical Research Centre.
In recent years several major investments in laser processing have been started at public technical colleges and schools, which have included, in their teaching facilities, Nd:YAG and diode lasers and sheet metal processing centers with laser cutting.
In 1988 a Beam Processing Club was established by the Finnish Welding Society to increase the interest of laser and electron beam processing. It has been active in arranging seminars and other events for specialists to meet. Recently it also established a Laser Forum, which is a member society for interested companies to meet and update their know-how with research facilities in the country.
Veli Kujanpää is professor of laser welding at Lapeenranta University of Technology, Finland.