Theses and Final Projects

Master's Thesis / Simon Van den Hende

Autogenous laser welding has shown many advantages over traditional welding methods in numerous applications. Still the process has disadvantages, e.g. limited area of thickness and tight tolerances in groove manufacturing. The research work has been carried out to overcome these disadvantages.

In this study, tests were made with a fiber laser using a constant power of 6 kW. Single and multi pass techniques were used to weld various thick austenitic stainless steel sections. Very narrow grooves were used because of the lack of filler material. Many problems have been noticed, evaluated and solved. A good view of multi pass laser welding has been created. Tests were made up to a thickness of 22,5 mm. Good results were found up to a thichness of 10-12 mm. Welding thicker plates becomes a lot more difficult, though it is not impossible.

Master's Thesis / Teemu Hiltunen

This master’s thesis concentrates on laser and its usage to laser welding. Laser sets its own requirements to product design and fixing methods of laser welded products. In addition usage of laser in machine shop places requirement to work environment. In this master’s thesis one box made of sheet metal was redesigned and found out is the box possible to weld tightly with lasers. The box was suitable for laser welding but fully tight welded box was challenging and uncertain to weld.

Master's Thesis / Marko Vattulainen

The master’s thesis examines the welding product development, design implementation and development of welding used in the workshop. Manufacturing companies know their own technical problems, but the initiation of development is often difficult or not even started. Smaller companies often lack the possibilities and knowledge of new production methods and product development. This master’s thesis will provide advice on how to lower the threshold for initial development work and it helps to structure the design task. Product design is a demanding task because the usability and the cost of the product are decided at the design phase. Designers need to know the different manufacturing methods and the idea of manufacturing-friendly design, so that they can take into account manufacturability and assembly considerations. A good welding construction has a minimal amount of welding. Both modulation and standardization, as well as substitutive methods to welding have been used. This master’s thesis presents manufacturing-friendly "Design For Welding" -model, that goes through the specific features of welded structure from the point of view of design. The purpose of manufacturing-friendly welding is to reduce the order-specific design, welding, welding post-processing and tooling.

Bacherlor's Thesis / Mikko Lamminpää

This thesis was commissioned by Machine Technology Centre Turku Ltd. The aim of this project was to organize the operating engineer education and engineer workshop for Machine Technology Centre Turku Ltd because professionally skilled machinists are needed there. The assignments of different firms are fabricated in the engineer workshop. The assignments can be different types of engineering work, subcontract work, projects and so on. In this thesis operation models and contract forms were drawn up for the future operation of the engineer workshop and the operating engineer education. The operating engineer education moved from traditional teaching to assistant based teaching. A suitable organisation model was searched for to implement the engineer workshop which will be taken into practice when the operation of the engineer workshop starts during the year 2009.

Master's Thesis / Aki Piiroinen

This master's thesis examines the development of the welding processes. The beginning of the introduction describes the welding at present and in the future together with the status of actual welding in Finland. The part of advancements in welding processes is divided into two sections, first one concentrating on the welding of low alloyed steels and second one the welding of aluminum alloys. The section of welding of low alloyed steels presents friction stir welding, modified short arc welding, laser welding, laser hybrid welding and narrow gap welding. The section of welding of aluminum introduces laser welding, nmodified short arc welding, friction stir welding and AC-MIG welding. The practical part of the master's thesis verifies the advantages of the current development stage of the selected welding processes. The first series of tests is welding marine aluminum with different arc welding types. Comparison is made between MIG pulse welding, wire pulse welding, and CMT-welding. Welding tests shows that in CMTwelding create smaller welding deformations than MIG pulse welding. The welding of aluminum with oxide layer on top with CMT-welding process is resulting fever problems nthan MIG pulse welding. The arc lights up more easily on high welding speeds and weld pore sensitivity is lower. When welding aluminum butt joint at welding speed 40 cm/min with wire pulse welding and MIG pulse welding weld pore sensitivity is very low. Test’s aluminum plates were water jet cut and half of the plates were welded with oxide layer on top. Welding experiments second test series examine low alloyed manganese steel T-beam fiber laser welding. With five kilowatt laser power was successfully weld five meters long T-beams at welding speed 2 m/min. With tacheometry measuring and Tritop 3D coordinate measuring was verified that laser weld T-beam welding deformations was much smaller than Twin Submerged Arc Welding welded T-bars.