Machine Technology Center Turku Ltd.

Turku, Finland

Machine Technology Center Turku Ltd.

Turku, Finland

Time filter

Source Type

Islam M.,Lappeenranta University of Technology | Purtonen T.,Lappeenranta University of Technology | Piili H.,Lappeenranta University of Technology | Salminen A.,Lappeenranta University of Technology | And 2 more authors.
Physics Procedia | Year: 2013

Powder bed fusion is a laser additive manufacturing (LAM) technology which is used to manufacture parts layer-wise from powdered metallic materials. The technology has advanced vastly in the recent years and current systems can be used to manufacture functional parts for e.g. aerospace industry. The performance and accuracy of the systems have improved also, but certain difficulties in the powder fusion process are reducing the final quality of the parts. One of these is commonly known as the balling phenomenon. The aim of this study was to define some of the process characteristics in powder bed fusion by performing comparative studies with two different test setups. This was done by comparing measured temperature profiles and on-line photography of the process. The material used during the research was EOS PH1 stainless steel. Both of the test systems were equipped with 200 W single mode fiber lasers. The main result of the research was that some of the process instabilities are resulting from the energy input during the process. © 2013 The Authors.


Matilainen V.,Lappeenranta University of Technology | Piili H.,Lappeenranta University of Technology | Salminen A.,Lappeenranta University of Technology | Salminen A.,Machine Technology Center Turku Ltd. | And 2 more authors.
Physics Procedia | Year: 2014

Laser additive manufacturing (LAM) enables production of complex parts with good mechanical properties. Nevertheless, part manufacturing is still relatively slow and the process efficiency could be improved to achieve total breakthrough into series production. In this study, the process efficiency improvements via higher laser power and thicker powder layers are studied. Effect of the building parameters must be understood when increasing build rate. Track-wise and layer-wise manufacturing strategy involves different independent and dependent thermal cycles which all affect part properties. Effects of the processing parameters such as speed and power on single-track formation are examined, since the part quality depend strongly on each single-track and layer. It was concluded that heat input has important effect on the penetration depth and possibility to melt thicker powder layers. These were noticed to be crucial for improving process efficiency. © 2014 The Authors. Published by Elsevier B.V.


Unt A.,Lappeenranta University of Technology | Lappalainen E.,Lappeenranta University of Technology | Salminen A.,Lappeenranta University of Technology | Salminen A.,Machine Technology Center Turku Ltd.
Physics Procedia | Year: 2013

This paper is focused on the welding of low alloy steels S355 and AH36 in thicknesses 6, 8 and 10 mm in T-joint configuration using either autogeneous laser welding or laser-arc hybrid welding (HLAW) with high power fiber lasers. The aim was to obtain understanding of the factors influencing the size of the fillet and weld geometry through methodologically studying effects of laser power, welding speed, beam alignment relative to surface, air gap, focal point position and order of processes (in case of HLAW) and to get a B quality class welds in all thicknesses after parameter optimization. © 2013 The Authors.


Salminen A.,Lappeenranta University of Technology | Salminen A.,Machine Technology Center Turku Ltd.
Mechanika | Year: 2010

Laser welding is gaining new applications in various industries. Often the use of filler wire is not considered due to reputation of complicity. This study has, however gained almost no interest of research groups after millennium. The study showed that when certain rules are followed the filler wire feeding can be used and applied to industrial applications. The reflection of the laser beam from wire surface can be considerable, but I can be controlled due to its behavior according to the normal reflection laws. Even the fraction of beam reflecting from the wire surface can be utilized to the process.


Purtonen T.,Lappeenranta University of Technology | Kalliosaari A.,Lappeenranta University of Technology | Salminen A.,Lappeenranta University of Technology | Salminen A.,Machine Technology Center Turku Ltd.
Physics Procedia | Year: 2014

Monitoring of laser processes has been researched actively since the 1980's in several institutes around the world. The goal of process monitoring is to gather information on the process and to improve the understanding of the occurring phenomena, and to use the gathered data to create quality control methods and adaptive, closed loop control of the process. The methods used for laser process monitoring can be divided into optical and acoustic methods of which the optical methods are more common. Today, monitoring has been commercially applied to even the newest laser processes, e.g. additive manufacturing. For laser welding, the process monitoring has been developed even further and closed-loop systems have been demonstrated several years ago. The improvements in digital camera technology and data processing have resulted in development of systems that use feature recognition for determining certain features of the process. Monitoring systems have developed from simple systems using single sensors to a more sophisticated systems utilizing a multitude of different detectors and detection methods. © 2014 The Authors. Published by Elsevier B.V.


Sokolov M.,Lappeenranta University of Technology | Salminen A.,Lappeenranta University of Technology | Salminen A.,Machine Technology Center Turku Ltd.
Physics Procedia | Year: 2014

The aim of this paper is to evaluate methods for improving laser beam welding efficiency, namely, obtaining increased penetration depth and enhanced weld quality without an increase in laser power or a decrease in welding speed. Increased efficiency can be realized with several techniques: butt joint edge surface modifications, preheating and modifications of ambient atmospheric conditions. Methods for laser beam welding process efficiency improvement are analysed and compared both separately and combined. Improvement in penetration depth or welding speed with similar penetration depth was noted for all the techniques studied. © 2014 The Authors. Published by Elsevier B.V.


Wandera C.,Lappeenranta University of Technology | Kujanpaa V.,Lappeenranta University of Technology | Kujanpaa V.,VTT Technical Research Center of Finland | Salminen A.,Lappeenranta University of Technology | Salminen A.,Machine Technology Center Turku Ltd.
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture | Year: 2011

The high-power fibre laser presents a possibility for the application of solid-state lasers in thick-section metal cutting, a field which has been dominated by high-power CO 2 lasers. The current paper presents the lumped-parameter formulation of the laser power requirement as a function of cutting speed for oxygen-assisted laser cutting of mild steel and nitrogen-assisted laser cutting of stainless steel. The calculated laser power requirement is compared with the incident laser power used in the cutting of 15mm mild steel with oxygen assist gas and 10mm stainless steel with nitrogen assist gas using a multi-mode 5kW fibre laser and a 4kW CO 2 laser. The incident laser power required for cutting at a given cutting speed is found to be lower for fibre laser cutting than for the CO 2 laser cutting, indicating a higher absorption of the fibre laser beam. The effects of process parameters on the cut kerf quality in mild steel laser cutting with oxygen assist gas using the high-power fibre laser are presented. The critical process parameters affecting the quality of the cutting process and the resulting cut kerf are the cutting speed, oxygen pressure, and nozzle diameter.


Unt A.,Lappeenranta University of Technology | Poutiainen I.,Lappeenranta University of Technology | Salminen A.,Lappeenranta University of Technology | Salminen A.,Machine Technology Center Turku Ltd.
Physics Procedia | Year: 2015

In this paper, a study of laser-arc hybrid welding featuring three different process fibres was conducted to build knowledge about process behaviour and discuss potential benefits for improving the weld properties. The welding parameters affect the weld geometry considerably, as an example the increase in welding speed usually decreases the penetration and a larger beam diameter usually widens the weld. The laser hybrid welding system equipped with process fibres with 200, 300 and 600 μm core diameter were used to produce fillet welds. Shipbuilding steel AH36 plates with 8 mm thickness were welded with Hybrid-Laser-Arc-Welding (HLAW) in inversed T configuration, the effects of the filler wire feed rate and the beam positioning distance from the joint plane were investigated. Based on the metallographic cross-sections, the effect of process parameters on the joint geometry was studied. Joints with optimized properties (full penetration, soundness, smooth transition from bead to base material) were produced with 200 μm and 600 μm process fibres, while fiber with 300 μm core diameter produced welds with unacceptable levels of porosity.


Vanska M.,Lappeenranta University of Technology | Abt F.,University of Stuttgart | Weber R.,University of Stuttgart | Salminen A.,Lappeenranta University of Technology | And 2 more authors.
Physics Procedia | Year: 2013

The material and parameters like welding speed and laser beam parameters define the geometry of the keyhole. The keyhole geometry affects the weld geometry, such as width and depth, and in some cases it should be considered when selecting welding parameters. In-situ X-ray videography makes it possible to obtain time-and space resolved information about the keyhole geometry during the welding process. This paper describes the partial penetration laser welding experiments and shows the effects of a welding speed and a focal point position change onto some geometry values of the keyhole. Two different joint types were used, bead on plate to simulate a very good machined joint preparation and laser cut I-butt joint. © 2013 The Authors.


Purtonen T.,Lappeenranta University of Technology | Salminen A.,Lappeenranta University of Technology | Salminen A.,Machine Technology Center Turku Ltd.
Welding in the World | Year: 2014

Laser fusion cutting is a widely used process to cut stainless steel sheets and plates. In best cases, it provides such a good quality that it can be used instead of machining, e.g.; for manufacturing tube systems and components where accurately cut holes and sections are required. The flexibility of fiber lasers provides a fast and affordable way to accomplish these demands. This paper examines the effect of cutting position on fiber laser cutting of stainless steel. The tests consist of flat sheet bevel cutting, cutting of tubes in vertical and nonvertical positions and orbital cutting. The effect of different cutting positions and parameters to the final quality of the cut edge are studied. The parameters were, e.g.; material thickness, focal length, cutting speed, and laser power. The cutting tests were performed as high-pressure nitrogen cutting using a 5-kW multi-mode fiber laser. It was shown that the changed angle of incidence in the cutting direction had affected the cutting result. With a pushing cutting position, both the cutting quality and performance were improved. The results indicated clearly that orbital cutting is possible with the same parameters that are suitable for cutting in vertical position. © 2013 International Institute of Welding.

Loading Machine Technology Center Turku Ltd. collaborators
Loading Machine Technology Center Turku Ltd. collaborators