Friction Stir Welding using Mazak VCN-430a Milling Centre and Taguchi’s robust design method finding optimum parameters.

Master's thesis in Stuctural EngineeringFriction Stir welding has become an important method for welding of aluminium alloys. Excellent mechanical properties, economic benefits and environment friendly is just some of the advantages compared to ordinary fusion welding. However, large investments are needed as the workpiece need to be clamped properly against the worktable to resist any movement and the machine have to produce a large downforce. FSW can be performed using ordinary CNC- machines but force control or position control are suggested to make sound welds. This experiment used a Mazak VCN430a vertical milling centre and tools from Stirweld. The welding was conducted without any force control or force measuring system. To get a better control of the shoulder depth, the plates surface was measured using a measuring probe and the surface curvature was interpolated along the weld path. Friction stir welding was successfully performed on 300x150x3 mm plates of AA6082-T6 alloy using the Tagushi robust design approach. Optimal parameters for this particular machine and experiment was found to be 1200 rpm for the rotation speed, 150 mm/min for the welding speed, 2 seconds dwell time and a shoulder depth of 0.11 mm. The matrix experiment revealed almost the same value for the 0.07 mm shoulder depth which can be a prove of interaction among the parameters. Ultimate tensile strength test for the optimal weld parameters was 222.7 MPa. The predicted value was higher, but the measured value was inside the 2-standard confidence interval. Vickers hardness test showed that weakening of material had occurred throughout the specimen. The measured value 60 mm from the weld centre was approximately 75 Vickers HV. Developing the welding jig, clamping system and also simultaneously finding welding parameters without having any force control or position control proved itself to be very difficult. The clamping system seemed to be the most important factor to be able producing sound welds. For further friction welding experiment a welding jig and clamping system with the possibility of force control or position control need to be considered to eliminate defects

DIG-MAN: Integration of digital tools into product development and manufacturing education

General objectives of PRODEM education. Teaching of product development requires various digital tools. Nowadays, the digital tools usually use computers, which have become a standard element of manufacturing and teaching environments. In this context, an integration of computer-based technologies in manufacturing environments plays the crucial and main role, allowing to enrich, accelerate and integrate different production phases such as product development, design, manufacturing and inspection. Moreover, the digital tools play important role in management of production. According to Wdowik and Ratnayake (2019 paper: Open Access Digital Tool’s Application Potential in Technological Process Planning: SMMEs Perspective, https://doi.org/10.1007/978-3-030-29996-5_36), the digital tools can be divided into several main groups such as: machine tools and technological equipment (MTE), devices (D), internet(intranet)-based tools (I), software (S). The groups are presented in Fig. 1.1. Machine tools and technological equipment group contains all existing machines and devices which are commonly used in manufacturing and inspection phase. The group is used in physical shaping of manufactured products, measurement tasks regarding tools and products, etc. The next group of devices (D) is proposed to separate the newest trends of using mobile and computer-based technologies such as smartphones or tablets and indicate the necessity of increased mobility within production sites. The similar need of separation is in the case of internet(intranet)-based tools which indicate the growing interest in network-based solutions. Hence, D and I groups are proposed in order to underline the significance of mobility and networking. These two groups of the digital tools should also be supported in the nearest future by the use of 5G networks. The last group of software (S) concerns computer software produced for the aims of manufacturing environments. There is also a possibility to assign the defined solutions (e.g. computer programs) to more than one group (e.g. program can be assigned to software and internet-based tools). The main role of tools allocated inside separate groups is to support employees, managers and customers of manufacturing firms focused on abovementioned production phases. The digital tools are being developed in order to increase efficiency of production, quality of manufactured products and accelerate innovation process as well as comfort of work. Nowadays, digital also means mobile. Universities (especially technical), which are focused on higher education and research, have been continuously developing their teaching programmes since the beginning of industry 3.0 era. They need to prepare their alumni for changing environments of manufacturing enterprises and new challenges such as Industry 4.0 era, digitalization, networking, remote work, etc. Most of the teaching environments nowadays, especially those in manufacturing engineering area, are equipped with many digital tools and meet various challenges regarding an adaptation, a maintenance and a final usage of the digital tools. The application of these tools in teaching needs a space, staff and supporting infrastructures. Universities adapt their equipment and infrastructures to local or national needs of enterprises and the teaching content is usually focused on currently used technologies. Furthermore, research activities support teaching process by newly developed innovations. Figure 1.2 presents how different digital tools are used in teaching environments. Teaching environments are divided into four groups: lecture rooms, computer laboratories, manufacturing laboratories and industrial environments. The three groups are characteristic in the case of universities’ infrastructure whilst the fourth one is used for the aims of internships of students or researchers. Nowadays lecture rooms are mainly used for lectures and presentations which require the direct communication and interaction between teachers and students. However, such teaching method could also be replaced by the use of remote teaching (e.g. by the use of e-learning platforms or internet communicators). Unfortunately, remote teaching leads to limited interaction between people. Nonverbal communication is hence limited. Computer laboratories (CLs) usually gather students who solve different problems by the use of software. Most of the CLs enable teachers to display instructions by using projectors. Physical gathering in one room enables verbal and nonverbal communication between teachers and students. Manufacturing laboratories are usually used as the demonstrators of real industrial environments. They are also perfect places for performing of experiments and building the proficiency in using of infrastructure. The role of manufacturing labs can be divided as: • places which demonstrate the real industrial environments, • research sites where new ideas can be developed, improved and tested. Industrial environment has a crucial role in teaching. It enables an enriched student experience by providing real industrial challenges and problems

Impact on health when sugar is replaced with intense sweeteners in soft drinks, ‘saft’ and nectar. Opinion of Vitenskapskomiteen for mattrygghet Norwegian Scientific Commitee for Food Safety

publishedVersio

Estimates of stock size of northeast Arctic cod and haddock, "Sebastes mentella" and "Sebastes marinus" from survey data, winter 1988

An acoustic survey and a bottom trawl survey for cod and haddock were carried out in the Barents Sea during the winter 1988. The fish still had the westerly distribution established in the previous year, but the echo abundance was substantially lower for both cod and haddock. The results of the surveys confirm the declining trend in recruitment. Abundance indices for redfish indicate that the stock situation is stabilizing for Sebastes mentella, but give cause for great concern for the Sebastes marinus stock. An acoustic survey on the spawning grounds of cod in the Lofoten-Vesterålen area was carried out after the Barents Sea survey. The estimate of mature cod was only 37% of the 1987 estimate

Estimates of stock size of Northeast Arctic cod and haddock from survey data 1986/1987

Combined acoustic and bottom trawl survey for cod and haddock were carried out in the Svalbard area in autumn 1986 and in the Barents Sea during the winter 1987. An acoustic survey for spwaning cod was carried out in March 1987 in the Lofoten area. The results show that the stocks are still increasing, but not as fast as previous surveys have indicated. One possible reason for this is that fish abundance in relatively shallow waters may have been generally overestimated by the current acoustic survey method

Marine indikatorer

The Nature Index (NI) is established to get an overview of the state and development of biodiversity within the major ecosystems of Norway. It includes marine, limnic and terrestrial ecosystems. The aim of the index is to measure if Norway manage to halt the loss of biodiversity by the end of 2010. A number of indicators are chosen to represent the state of biodiversity. 125 scientists from various disciplines of research have contributed with data, expert judgements or modeled data for 310 indicators representing different aspects of biological diversity, such as trophic levels, key species and threatened and common species. In order to assemble all the data to an index, a reference value has been estimated for each indicator. The reference value reflects an ecological sustainable value for the indicator, and the indicator values displays eventual divergence from this state. This report describes how data on reference values, uncertainty and values for 1950, 1990, 2000 and 2010 has been set for each indicator. Furthermore this report documents the data sources for each of the indicators that are included in the data set

Impact on health when sugar is replaced with intense sweeteners in soft drinks, ‘saft’ and nectar. Opinion of Vitenskapskomiteen for mattrygghet Norwegian Scientific Commitee for Food Safety

publishedVersio