Glass has been a key material for many important advnces in cilivilization.  Currently there is much scientific and technological interest to obtained flat/float glass surface that has extremely highly resistant to abrasion, anti-fingerprint, surface contamination and optical dimming. The aim of current project is to develop new routes to modify the glass surface in order to increase functionality and enhance performance in various existing and future areas of application. This will be achieved by modifying the glass surface by incorporating nitrogen to the flat/float glass surface by deposition of thin coatings of AlN, Si₃N₄ and TiN. This will be achieved by gas to particle conversion by physiochemical routs. Thin films of elemental nitrides have not been reported previously by aerosol technique and we anticipate that these can be used to enhance the mechanical, optical and chemical properties of flat/float glass surface. Techniques used for structural and physical characterization include, SEM, TEM, AFM, Raman, thermal analysis, mechanical and optical measurements. Areas of applications of these modified surfaces include automotive, architectural, laser optics, camera lenses, optical filters and display technologies.

In this work, amorphous thin films in Mg-Si-O-N system typically containing >15 at.% Mg and 35 at.% N were prepared in order to investigate especially the dependence of optical and mechanical properties on Mg composition. Reactive RF magnetron co-sputtering from magnesium and silicon targets were used for the deposition of Mg-Si-O-N thin films. Films were deposited on float glass, silica wafers and sapphire substrates in an Ar, N₂ and O₂ gas mixture. X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, spectroscopic ellipsometry, and nanoindentation were employed to characterize the composition, surface morphology, and properties of the films. The films consist of N and Mg contents up to 40 at.% and 28 at.%, respectively and have good adhesion to substrates and are chemically inert. The thickness and roughness of the films increased with increasing content of Mg. Both hardness (16–21 GPa) and reduced elastic modulus (120–176 GPa) are strongly correlated with the amount of Mg content. The refractive index up to 2.01 and extinction coefficient up to 0.18 were found to increase with Mg content. The optical band gap (3.1–4.3) decreases with increasing the Mg content. Thin film deposited at substrate temperature of 100 °C shows a lower value of hardness (10 GPa), refractive index (1.75), and higher values of reduced elastic modulus (124 GPa) as compared to the thin film deposited at 310 °C and 510 °C respectively, under identical synthesis parameters.

ABSTRACT

This is a summary of the formal part of our project. During the autumn of 2007 and spring 2008 we have done an overhaul on one of the auxiliary engines onboard Calmare Nyckel. The assignment was given from Egon Nilson. The engine was in bad shape, lubrication oil and coolingwater was leaking from several cylinders and thereby in big need of a service. There have been some waiting time during the order of new parts because of the rare engine type which are British and therefore all the parts had to be ordered from England. At the end of the project we discovered some difficulties with coolingwater leaking in to the oil sump, this causing further delays finishing the project. The problem were solved and at the test run the engine run satisfactory.

During the project we have as far as possible followed the manual and other instructions available.

During a project like this it is important that all documentation of the project is shown.

The materials that are shown are presented with an introduction followed by the process and the result. To this documentation we have attached a working diary and quotations.

Aktuell rapport redovisar resultatet av en förstudie över hur man med hjälp av nanoteknologi skulle kunna förbättra ytbehandlingen av en trähusfasad så att ett mervärde skapas.

 För ytbehandling finns idag många tillämpningar där nanotekniken utnyttjas för att skapa mervärde hos en yta jämfört med vad dagens mer traditionella produkter kan erbjuda. Nanobaserade ytbehandlingsprodukter marknadsförs idag som uppges göra ytor smuts- och vattenavvisande, förhindrar påväxt av alger, svamp och mossa, med förbättrad UV- och temperaturresistens och kulörbeständighet, förbättrad reptålighet och nötningshärdighet, samt med antigraffiti egenskaper etc.  De flesta produkterna är dock nya och för en del finns därför frågor som gäller t.ex. långtidsprestanda och teknisk livslängd, underhållsbarhet och därmed sammanhängande ekonomi sett ur ett livscykelperspektiv för den produkt eller system där ytbehandlingen utgör bara en del.

 Många nanoteknikbaserade färger som beskrivs i rapporten finns för mineraliska underlag men mycket få kan rekommenderas för ytbehandling av utvändigt trä dock. Mycket utvecklingsarbete pågår emellertid och vår bedömning är att många av de nanoteknikbaserade ytbehandlingsprodukter som idag finns för mineraliska underlag kommer att kunna modifieras för användning också på utvändigt trä inom ett icke alltför avlägsen framtid.

 I förstudien ingick att uppskatta den ekonomiska potentialen för hur ökad funktionalitet hos ett nanoteknologibaserat ytbehandlingssystem skulle kunna ge ett mervärde. Vi fann att mervärdet bäst kan uttryckas i termer av minskade underhållskostnader relativt de som kännetecknar de mer traditionella material och tekniker som idag används för ytbehandling av trähusfasader. Våra slutsatser är att en trähusfasad, som är smutsavvisande och förhindrar påväxt, borde kunna reducera underhållskostnaderna väsentligt genom att minska eller kanske helt eliminera behovet av fasadrengöring mellan två ommålningar. Vilka förbättringar man kan få med dagens nanobaserade ytbehandlingsprodukter i termer av längre underhållsintervaller är svårare att säga men vi bedömer ändock att det borde vara möjligt att åstadkomma kanske så mycket som en 50 % förlängning av intervallet för förnyad ytbehandling.

 För de mest intressanta nanoteknologibaserade ytbehandlingssystemen bedömer vi dock genomförandet av en flerårig fältmässig utvärdering som motiverad. Syften med studien skulle vara att från resultaten uppskatta nödvändigt intervall för fasadtvätt, förnyad ytbehandling och risk för rötangrepp hos de undersökta färgsystemen, utnyttja resultaten också till att uppskatta skillnader i underhållskostnader mellan de nanoteknologibaserade färgsystemen och referenssystem som baserar sig på användning av traditionell ytbehandlingsteknik samt i detta sammanhang även utvärdera färgsystemens underhållsbarhet avseende långtidsegenskaper efter förnyad ytbehandling          

In the production of glass, the addition of more cullet to the batch of glass and the reduction of the thickness of glass are means to reduce energy consumption and raw material usage. This contributes towards improved energy efficiency targets of the European Union. This thesis investigated the energy consumed for the process of strengthening thinner glass as well the environmental implications of thinner and stronger compared to conventional glass across the life cycle of glass. The life cycle phases also included a recycling phase where 70% of the used glass was recycled with the remaining 30% being landfilled. The functional unit selected for this study was 1m2 of SLS glass, 4mm thick, with an average light transmittance of 91%. This corresponds to 10kg of clear float glass as per general rule. The findings of this thesis showed that one of the major contributing factors to high energy consumption in the melting phase of SLS glass is low efficiency of the furnace; this led to significant energy losses in the production of SLS glass. Recycling of flat glass, at a 70% rate, led to a 12% reduction in total global warming potential, a 10% reduction in the Acidification Potential, a 13% reduction in the Eutrophication Potential in marine environs, and a 7% reduction in the Eutrophication Potential in terrestrial habitats. The chemical and thermal strengthening process consumed 2.24 and 2.37 kWh/m2 respectively. The consequential impact of this is dependent on the source of the electricity for the strengthening processes. It was concluded that the energy used for the strengthening of the thinner glass is considerably less than the energy used in the production of a conventional glass that satisfies the same strength parameters.

Previous research within friction stir welding (FSW) has demonstrated that online control of welding parameters can improve the mechanical properties and is necessary for certain applications to guarantee a consistent weld quality. One approach to control the process is by adapting the heat input to maintain a stable welding temperature, within the specified operating boundaries. This requires accurate in-process temperature measurements. This paper presents a novel method to measure the temperature at the interface of the FSW tool and workpiece. The method is based on the thermoelectric effect between dissimilar materials. The measurements are compared to thermocouple measurements and to a physical model and show good correspondence to each other. Experiments demonstrate that the method can quickly detect temperature variations, due to geometrical variations of the workpiece or due to parameter changes. This allows use of the method for online control of robotic FSW.

Friction stir welding (FSW) of non-linear joints receives an increasing interest from several industrial sectors like automotive, urban transport and aerospace. A force-controlled robot is particularly suitable for welding complex geometries in lightweight alloys. However, complex geometries including three-dimensional joints, non-constant thicknesses and heat sinks such as clamps cause varying heat dissipation in the welded product. This will lead to changes in the process temperature and hence an unstable FSW process with varying mechanical properties. Furthermore, overheating can lead to a meltdown, causing the tool to sink down into the workpiece. This paper describes a temperature controller that modifies the spindle speed to maintain a constant welding temperature. A newly developed temperature measurement method is used which is able to measure the average tool temperature without the need for thermocouples inside the tool. The method is used to control both the plunging and welding operation. The developments presented here are applied to a robotic FSW system and can be directly implemented in a production setting.

This report was written as a result of a Bachelor Degree Project, together with Swepart Transmission AB. The report contains the construction of a hydraulic press for the assembly operation.

The project started with a new construction of a hydraulic press for the bearings’ assembly. The goal within the thesis work was to fit the three bearings to the housing by only one press motion. This operation should be very safety because of the sensitive tolerance at the bearings and housing. Construction of the cylinders, rams and bolster were the most important parts at this project because this parts’ functions are very important for this assembly.

The next step of this thesis was to calculate the hydraulic press components’ parameters and then choose the suitable components. The focus was to choose more useful and reliable components.

The hydraulic press was modeled in the CAD program Solid Works and 2D technical drawing was drawn in the Autocad. The frame material was chosen and the frame was analysised in the Solid Works.

Abstract (in English)

The work that lead to a CE- marking and the creation of a total drawing foundation on an existing machine carried out on the company Polytec Composites Sweden AB in Ljungby. The company have design an machine that exist in six example that runs in the production. To be able to use the machine the company have to work out a CE-marking. The process that summed up all the document that needs for the machine to make a CE-marking. The documentation includes a total drawing over the machine and a risk analysis performed by a group employers on the company. The computer program that i used to make the drawings is Catia V5. The work that the company and the student performed ended up in a CE-marking of the machine.

Valuable hardwoods, such as oak, although renewable, present limitations in product realisation in terms of their cost and availability, often attributed to production waste and sub-optimal product design factors. The slicing technique facilitates the production of thin wood lamellae, minimising waste and ensuring optimal material conversion. This study explores the application of sliced lamellae in engineered wood flooring, focusing on quality aspects and control. 

The performance of sliced lamella-based engineered flooring was compared with traditional parquet flooring elements through standard performance tests, which scrutinised the characteristics of appearance, delamination, and dimensional stability under varying climate conditions. The climate tests highlighted the significant flaws of sliced lamella-based flooring elements: surface-checking. Despite diminished delamination resistance, the dimensional stability excelled for the sliced lamella–based flooring. Primary observations indicated that the study’s constraints are related to a lack of surface-checking quantitative measurements and an absence of sliced lamellae quality control. 

The subsequent research characterised sliced lamellae quality using the properties of slicing checks and mechanical performance perpendicular to the grain. Slicing thickness is considered a critical variable in both lamella-processing and product performance factors. A detection method using image processing and analysis was developed to characterise slicing check occurrence. The method considered slicing check characteristics, check depth ratio and check frequency. The results of the slicing check inspection indicated a decrease in the check depth ratio and check frequency with increased slicing thickness. 

Mechanical testing revealed that oak sliced lamellae exhibited considerably lower strength and stiffness compared to sawn solid wood. The slicing check depth ratio was found to be negatively correlated with the sliced lamellae’s tensile strength and strain at break.

A novel method for detecting surface-checking was developed and employed. It utilised digital image correlation and analysis of full-field strain data. The novelty of the method is advancing the surface-checking quality index that considers the check length over the inspected area. This method was applied to engineered wood flooring to evaluate the impacts of core type and sliced lamellae nominal thickness on surface-checking results. Significant interactions between the studied variables were found, indicating that the surface-checking tendency could not be attributed to a single factor. Especially notable was the reduced surface-checking outcome in standard core specimens paired with a low lamella thickness. 

This thesis offers new insights into using sliced lamella in engineered wood flooring realisation. Although the assumed sliced lamellae quality aspects, slicing check depth and check frequency, were shown not to impact surface-checking, the significant interactions between engineered wood flooring construction parameters highlight the need for a broader perspective concerning this subject. 

Future research should focus on further refining the sliced lamellae quality analysis and developing new methods that consider other quality aspects.

The performance of multi-layered wood flooring produced with sliced and sawn top-layers was evaluated in this study. Slicing checks side orientation was evaluated by pressing the veneers with checks side oriented upwards and/or downwards the flooring surface. The performance of  produced flooring boards were evaluated using a climate chamber test with regard to the dimensional stability (SS-EN:1910) and appearance. Delamination resistance was tested according to the ANSI delamination testing procedures. Results of the climate chamber test revealed immerging of a high amount of slicing checks to the surface of parquet boards after the first dry cycle. Checks tend to be larger around knots. Checking was qualitatively assessed as being more severe on the boards with checks side up. Dimensional stability was assessed to be slightly better for the sliced top-layers compared to the sawn ones. Parquet elements produced with  veneers checks side facing downwards had poor delamination resistance. The best results regarding delamination resistance was achieved when using sliced lamellas with the checks side facing up

Collisions between vessels and allisions between vessel and obstacles as well as groundings constitute a great problem within the shipping business. Serious damage to vessels, environmental disasters and great costs are invoked for everyone involved. Is it possible that deficient bridge procedures are the reasons behind these types of accidents? The purpose of this thesis is to gather material from accident reports from the years 2000-2007, to investigate whether there are any connections between the accidents on Swedish merchant vessels which have been involved in collisions with each other, allided with an obstacle or that have grounded. The results showed, among other things, that motor tankers are involved in groundings more often than other types of vessels. On the basis of these results, interviews were carried out with motor tanker officers and pilots to investigate what the situation is like onboard during the circumstances where these vessels are most usually grounded. Several of the informants state that paperwork and checklists have become a burden to them during their bridge watches, and one of the implications of our investigation is that inadequate supervision could be the reason behind the accidents.

For additive manufacturing (AM) products such as structural and machinery components, the quality should be verified. In maritime industry, this task is performed by classification societies who are acting as independent third party and certifying such components. In the case of, eg, cast-steel products, standards are available, which specify sampling procedures, properties, and destructive and nondestructive test methods as well as relevant material requirements for design purposes. For AM products, currently only few supportive standards are available. In tough market situation products must be cost-efficient. Therefore, mandatory verification of products can only be enforced for vital applications. Unified, meaningful sampling and testing scopes are needed for application at different manufacturing locations and for evaluation by “no AM expert” staff. The impact of manufacturing defects in the AM process on the integrity on the AM product has to be evaluated. Contract partners may, or have to ask for evidence for the integritiy of AM products by certificates issued by third-party institutions. DNV GL as a classification society has set up procedures for initial qualification and certification of AM products. This paper focusses on inspection and certification of AM maritime products and fit-for-purpose assessment.

The aircraft industry is striving to reduce the weight of aircraft to save fuel and hence reduce total cost. New alloys and composites with properties such as low weight and high strength are continuously developed. Titanium alloys have the best strength-to-weight ratio among metals which makes them very suitable for aircraft applications. Ti-64 is the most common Titanium alloy used in aircraft. AA2099 is a 3rd generation Al-Li alloy and has the lowest density among all Aluminium alloys making it very attractive for aircraft applications. Pylons of commercial aircraft are currently made primarily with Ti-64 and this study focused on the replacement of Ti-64 with AA2099. Loading conditions, operating temperature, corrosion resistance, manufacturability and recyclability of the pylon were analysed of both Ti-64 and AA2099. Three critical scenarios were chosen for the loading conditions of the pylon. These were simulated using finite element analysis first using Ti-64 and then AA2099. From the results, it is evident that using AA2099 as the material of the pylon instead of Ti-64 offered weight savings. The operating temperature, manufacturability and recyclability also showed advantages when using AA2099 whereas corrosion factors favoured Ti-64, since AA2099 was found to be very prone to galvanic corrosion.

Weld joints play a very important role in assessment of structural integrity of steel structures. The weld joint region is the location of weld induced residual stress and strain fields (WRS). For the time being there is a lack of engineering methods to be used for approximations of the maximum WRS magnitudes in the way of a weld joint proposed to be produced with a specific Welding Procedure Specification (WPS). Or screening of residual stress measurement results obtained by various measuring methods. This report describes how one can proceed to establish best estimate material data by the use of the Meyer’s hardness. The Meyer’s hardness can also be used to determine the maximum physically possible WRS magnitude.

This document presents the DNV Platform of Computational Welding Mechanics, CWM, with its associated CWM-methodology. That has been developed, validated and implemented as a part of DNV’s Technology Leadership program in the field of Structural Integrity and Materials Technology.A successful CWM implementation requires that the actual organisation has gained the knowledge and understanding of the following related topics:- Welding Engineering with an emphasis on the welding process and its thermodynamics- Weld process quality control such as calibration, validation as well as DAQ, (Data Acquisition)- Transient thermo-mechanical coupled FE-analyses and constitutive modelling- Computational platforms comprising the selection of hardware, operative system and FEM-code as well as suitable pre- and post-processing toolsFrom that perspective there is a lack of reliable and/or hands-on oriented CWM Engineering Handbooks and best recommended practices available on the market. For that sake is the DNV CWM-methodology and its hands on solutions presented.The CWM-methodology described can not only be used for residual stress assessments, as presented in this report. It can also be used for various applications such as assessment of used and/or proposed WPS, Welding Procedure Specifications as well as optimisation of the manufacturing and production process of integrated metallic structures.From the results of a parametric CWM-study have three (3) factors been identified to drive and/or contribute to the magnitude of the weld residual stresses in ship steel plate materials. The contributing and/or driving factors identified are the:- Thermal- and Mechanical Boundary Conditions during the production welding- Yield stress difference between the base- and the weld filler material- Weld heat input, Q, which affects the weld cooling time

An algorithm for heat transfer prediction of in-service welding operations in a forcedflow of fluid is presented. The algorithm presented is derived from Rosenthal’s 3D heatflow equation and boundary layer approximations. This was possible by the introductionof an apparent thermal conductivity kPL, which is a function of the boundary layer’s heattransfer coefficient f and the base material’s thickness . This implies that a weldcooling time tT1 /T2 in a forced flow of fluid can now be calculated by an ordinaryengineering calculator and thus enabling suitable welding parameters to be determined.The magnitude of kPLf , was established by regression analysis of results from aparametric finite element analysis series of a total number of 112 numerical simulations.Furthermore, the result of the regression analysis was validated and verified by a weldingexperiment series accomplished on an in-house designed and constructed in-servicewelding rig. The principle design of the welding rig as well as its instrumentation, a PCbased Data Acquisition system, is described. In addition, a method to measure the weldmetals cooling time tT1 /T2 by means of thermocouple elements is described. Finally,the algorithm presented in this study proved feasible for industrial in-service weldingoperations of fine-grained Carbon and Carbon–Manganese steels with a maximum CarbonEquivalent (IIW) (CE) of 0.32.

A welding procedure specification is the document describing how a weld joint should be constructed. Arc weld processes are characterized by transient thermal behavior, leading to rapid changes in material properties and dynamic interaction between weld and base material. The objective of the project is to explore how the use of an improved CWM-platform affects representative stress and strain fields in order to assess welding procedure qualification records. Forthis project, the accumulated thermal and mechanical influences from the first run to the final run are brought forward, in one and the same meshed geometrical model. Both the thermal and mechanical material model of the platform are designed to be used for modelling of the base- and weld material,promoting the simulation of the intricate combination of the thermal, elastic,and plastic strains on the plastic strain hardening and the formation of residual stress fields. The output of the simulation is mainly weld cooling times, residual stresses, and deformations. This analysis is taken further by examining how residual stresses influence crack driving force under elastic and plastic loading. In addition, the output from the simulations can be used to assess the realism of the proposed welding parameters. The main experimental welding procedure examined comes from the IIW RSDP Round Robin Phase II benchmark project, where the main aim was to benchmark residual stress simulations. This work was found to contain many applicable challenges of a CWM-analysis project.

Due to the past crises, the shipbuilding and offshore industry has realised that new innovative designs and design and production methods are necessary to decrease operational costs, production costs and emissions,while meeting the changing rules and regulations. This ISSC-V.3 report is discussing recent developmentin materials and fabrication technology applied to ship and offshore structures.Chapter 2 focuses on worldwide trends in materials and fabrication methods. Developments in metallicand non-metallic structural materials are dealt in Chapter 3. Advances in fabrication and joining technologiessuch as welding are increasing. Some main areas of applications and research in those areas aredescribed in Chapter 4. Innovative development about corrosion protection systems are presented inChapter 5 while Chapter 6 give an overview about the application of production simulation and virtualreality to improve the production management of ship and offshore structures.The ISSC-V.3 technical committee has performed a benchmark to define a Best Practice Guideline touse Computational Welding Mechanics tools (CWM) in shipbuilding and offshore industry. To achievethis objective various experimental welding tests have been performed in order to give a reference point.Both the residual welding distortions and residual stresses have been compared between numerical simulationsand welding experiments for a common “T” welded assembly used in the shipbuilding industry.However, it has been decided to publish the results of this study in a separate document. Nevertheless, Chapter 7 of this report presents the state of the art as well as the experimental test case that has been analysed.

The strength of a weld joint is determined by its geometry and its metallurgic structure, which is dependent on the cooling rate, its chemical composition and the original grain size of the base material. During in-service welding of structures affected by a forced flow of fluid on its reversed side the cooling rate depends on the fluid’s boundary layer, the material’s thickness and the heat input of the welding process. Currently, the calculation of the cooling rate during in-service welding is made by means of numerical methods such as the Finite Element Method, FEM. Through the introduction of an apparent thermal conductivity, kPL, it possible to determine the cooling rate for specific welding parameters by means of Rosenthal’s equation. This can be done with a standard pocket calculator.An experimental rig for measurement of the heat transfer during the in-service welding of structures affected by a forced flow of fluid on its reversed side has been designed and built. The physical principles of welding on plates affected by a forced flow of fluid on their reverse side are the same as for welding on the circumference of a pipe containing a forced flow of fluid. In the rig, the required boundary layer is built up in a pipe system by means of a pump. As the flow and the temperature of the fluid can be controlled to simulate the specific heat transfer, it is now possible to verify the values of the apparent thermal conductivity, kPL, that were calculated

values of the apparent thermal conductivity, k_PL, for various configurations.For the purpose of evaluation and qualification of in-service Welding Procedures Specifications, WPS, the sponsors of the research project use the experimental rig.

An algorithm to estimate the cooling rate of welding seamson the shell plating of a ship, below the waterline, while it is onvoyage has been derived. The demand for this technique hasarisen from the wish of ship operators to make it possible forthe safe repair of ship structures without taking them out ofoperation. [1] The strength of the shell plating after welding isdetermined by its metallurgic structure, which is dependent onthe cooling rate, its chemical composition and the original grainsize of the base material. [2] The cooling rate for this type ofwelding seam depends on the velocity of the water flow, thedistance from the bow, the thickness of the plate, and the heatfrom the heat input of the welding. The algorithm makes itpossible to calculate the cooling rate for a base material affectedby a forced flow of fluid by means of Rosenthal’s equation andthus enabling suitable welding parameters to be determined.As the welding parameters can be chosen to fit the specificrepair to be made, it is now possible to determine the suitabilityof a welding procedure in advance. The algorithm is applicablewhen determining welding parameters at Hot-Tappingoperations as well, where the base material is affected by aforced flow of fluid. A number of experiments have beenperformed and the results support the theoretical model. Theresearch project continues with the aim of finding an algorithmto include the enhanced cooling rate due to the layer of boilingfluid on the back of the base material. A method to improve themeasurements of the most important parameter in the algorithmhas been developed and makes it possible to build up aquantitative database of typical values for various configurations.

Weld joints play a very important role in the assessment of structural integrity of steel structures. The likelihood of defects is significantly higher in the weld joint compared to the unaffected base material. Here the Computational Welding Mechanics platform developed by Lindström (2015) has been used to model representative residual stress fields by the use of the IIW RSDP Phase II Initiative documentation (Janosch 2001). Where the CWM-platform includes an option for tracking the welding’s influences on the evolution of the base and weld material’s tensile properties. A detectable defect is introduced in the weld metal and the crack driving force in terms of the CTOD is extracted from the FEA. The loading applied covers both globally elastic and fully plastic conditions. The analysis allows evaluation of the influence of both residual stresses and changes in the tensile properties on the crack driving force as a function of applied global load.

Thin films in the aluminosilicate (AlSiO) system containing up to 31 at. % Al and 23 at. % Si were prepared by reactive RF magnetron co-sputtering in order to investigate the dependence of film formation and optical properties on substrate temperature and Si and Al contents. The obtained films were amorphous with smooth microstructure. The growth rate at different substrate temperatures ranged from 1.2 to 3.3 nm/min and increase with increasing the Si target power. The roughness decreases and thickness increases with increasing Si content. The thickness of the films grown at a deposition temperature of 100 °C is found to be higher than the films deposited at 300 and 500 °C. The AlSiO-coated glasses have a higher transmission in the visible region than the uncoated glass. The spectroscopic ellipsometry analysis reveals that the refractive index value decreased with decreasing the Al content, having extinction coefficient values of zero in the measured spectral region and band gap values ≥ 3.4 eV. The obtained thin films have over 90% transmittance in the visible range and no systematic variation of transmittance was observed with substrate temperature. The results suggest that glass substrate coated with AlSiO thin films have improved optical properties. 

This thesis concerns experimental investigations of laser cutting with theoretical and practical discussions of the results. The thesis is made up of three papers which are linked in such a way that each of them studies a different aspect of laser cutting: In paper I the two major laser types in cutting, namely CO2 and fiber lasers, are compared to each other by a self-defined cut efficiency. Next in paper II the laser cutting process is observed with a high speed imaging, HSI, camera to give information about the melt flow in the cut zone. In paper III the initiation of the laser cutting process, called piercing, is studied. Paper I is about investigating the effect of material type, material thickness, laser wavelength, and laser power on the efficiency of the cutting process for industrial state-of-the-art cutting machines. Here the cutting efficiency is defined in its most fundamental terms: as the area of cut edge created per Joule of laser energy. This paper presents phenomenological explanations for the relative cutting efficiencies of fiber lasers and CO2 lasers and the mechanisms affecting these efficiencies for stainless steels and mild steel over a range of thicknesses. The paper also involves a discussion of both theoretical and practical engineering issues.In Paper II a new experimental technique has been developed which enables High Speed Imaging of laser cut fronts produced using standard, commercial parameters. The results presented here suggest that the cut front produced when cutting 10 mm thick medium section stainless steel with a fibre laser and a nitrogen assist gas is covered in humps which themselves are covered in a thin layer of liquid. A combination of HSI results and theoretical analysis has revealed that these humps move down the cut front at an average speed which is a factor three less than the liquid flow speed. Paper III addresses a specific topic: Before any cut is started the laser needs to pierce the material. The two most important aspects of the piercing process are: a) How long does it take to pierce the material? And b) How wide is the pierced hole? If the hole is no wider than the cut line, the material can be pierced on the line to be cut. In this paper the laser piercing process is investigated using a wide range of laser pulse parameters, for stainless steel using a fibre laser, to discover their influence on pierce time and pierced hole diameter. A high speed imaging camera is used to time the penetration event and to study the laser-material interactions involved in drilling the pierced holes. Optimum parameters have been identified for both pierce time and pierce hole width.

This thesis concerns experimental investigations of laser cutting and piercing, with theoretical and practical discussions of the results. The thesis is made up of an introduction to laser cutting and six scientific Papers. These Papers are linked in such a way that each of them studies a different aspect of laser cutting: process efficiency in Paper I, morphology and melt flow on the laser cut front in Papers II, III and IV and laser piercing in Papers V and VI.

Paper I investigates the effect of material type, material thickness, laser wavelength, and laser power on the efficiency of the cutting process for industrial state-of-the-art CO2 and fibre laser cutting machines. Here the cutting efficiency is defined in its most fundamental terms: as the area of cut edge created per Joule of laser energy.

In Paper II a new experimental technique is presented which has been developed to enable high speed imaging of laser cut fronts produced using standard, commercial parameters. The results presented here suggest that the cut front produced when cutting 10 mm thick medium section stainless steel with a fibre laser and a nitrogen assist gas is covered in humps which themselves are covered in a thin layer of liquid. Paper III presents numerical simulations of the melt flow on a fibre laser ablation-driven processing front during remote fusion cutting, RFC. The simulations were validated with high speed imaging observations of the processing front. The simulation results provide explanations of the main liquid transport mechanisms on the processing front, based on information on the temperature, velocity and pressure fields involved. The results are of fundamental relevance for any process governed by a laser ablation induced front. In Paper IV cutting fronts created by CO2 and fibre lasers in stainless steel at thicknesses between 2 mm and 10 mm have been ‘frozen’ and their geometry has been measured. The resulting three-dimensional shapes have been curve fitted as ninth order polynomials. Various features of the cutting front geometry are discussed, including the lack of correlation of the cut front inclination with either the relevant Brewster angle or the inclination of the striations on the cut edge. In this paper, mathematical descriptions of the cutting fronts are obtained, which can be used as input parameters by any researcher in the field of laser cutting simulations.

Paper V investigates the subject of laser piercing. Before any cut is started the laser needs to pierce the material. In this paper the laser piercing process is investigated using a wide range of laser pulse parameters, for stainless steel using a fibre laser. The results reveal the influence of pulse parameters on pierce time and pierced hole diameter. A high speed imaging camera was used to time the penetration event and to study the laser-material interactions involved in drilling the pierced holes. In Paper VI a ‘dynamic’ or ‘moving beam’, laser piercing technique is introduced for processing 15 mm thick stainless steel. One important aspect of laser piercing is the reliability of the process because industrial laser cutting machines are programmed for the minimum reliable pierce time. In this work a comparison was made between a stationary laser and a laser which moves along a circular trajectory with varying processing speeds. High speed imaging was employed during the piercing process to understand melt behavior inside the pierce hole.

Throughout this work experimental techniques, including advanced high speed imaging, have been used in conjunction with simulations and theoretical analysis, to provide new knowledge for understanding and improving laser beam cutting and its associated piercing process.

Numerical simulations on the melt flow down the keyhole front during fibre laser welding are presented here. The calculations confirm the existence of melt waves previously observed by high speed imaging, with velocities ranging between 4 and 10 m/s. The simulations provide spatial and temporal information on the temperature and flow fields, particularly within the melt film volume, which cannot be observed by high speed imaging. The ablation pressure achieves high values around wave-peaks and at the bottom of the front, just before droplets are sheared off. The simulation results provide explanations on the main liquid transport mechanisms within the keyhole based on information on the temperature, velocity and pressure field and on the geometrical front conditions.

This paper investigates the effect of material type, material thickness, laser wavelength and laser power on the efficiency of the cutting process for industrial state-of-the-art cutting machines. The cutting efficiency is defined in its most basic terms: as the area of cut edge created per Joule of laser energy. This fundamental measure is useful in producing a direct comparison between the efficiency of fiber steels with different lasers from the point of view of one question: ‘How much cut edge is produced for each kilojoule of laser energy?’ This measure of efficiency can be described by the following simple equation; and CO2 lasers when cutting any material.

It is well known that the efficiency of the laser cutting process generally reduces as the material thickness increases, because conductive losses from the cut zone are higher at the lower speeds associated with thicker section material. However, there is an efficiency dip at the thinnest sections. This paper explains this dip in terms of a change in laser-material interaction at high cutting speeds.

Fiber lasers have a higher cutting efficiency at thin sections than their CO2 counterparts, but the efficiency of fiber laser cutting falls faster than that of CO2 lasers as material thickness is increased. This is the result of a number of factors including changes in cut zone absorptivity and kerf width.

This paper presents phenomenological explanations for the relative cutting efficiencies of fiber lasers and CO2 lasers, and the mechanisms affecting these efficiencies for stainless steels (cut with nitrogen) and mild steel (cut with oxygen or nitrogen) over a range of thicknesses. The paper involves a discussion of both theoretical and practical engineering issues.

This paper investigates the effect of material type, material thickness, laser wavelength, and laser power on the efficiency of the cutting process for industrial state-of-the-art cutting machines. The cutting efficiency is defined in its most basic terms: as the area of cut edge created per Joule of laser energy. This fundamental measure is useful in producing a direct comparison between the efficiency of fiber and CO2 lasers when cutting any material. It is well known that the efficiency of the laser cutting process generally reduces as the material thickness increases, because conductive losses from the cut zone are higher at the lower speeds associated with thicker section material. However, there is an efficiency dip at the thinnest sections. This paper explains this dip in terms of a change in laser–material interaction at high cutting speeds. Fiber lasers have a higher cutting efficiency at thin sections than their CO2 counterparts, but the efficiency of fiber laser cutting falls faster than that of CO2 lasers as the material thickness increases. This is the result of a number of factors including changes in cut zone absorptivity and kerf width. This paper presents phenomenological explanations for the relative cutting efficiencies of fiber lasers and CO2 lasers and the mechanisms affecting these efficiencies for stainless steels (cut with nitrogen) and mild steel (cut with oxygen or nitrogen) over a range of thicknesses. The paper involves a discussion of both theoretical and practical engineering issues.

The flow characteristics on the laser cut front for 10 mm stainless steel AISI 304 (EN 1.4301) are studied in this paper using High Speed Imaging (HSI). The laser cut samples were produced with a 6 kW fiber laser with nitrogen gas assist. Previous work in this field has used unusual cutting parameters to make the experimentation easier. This work presents, for the first time, HSI results from standard commercially viable cutting parameters. This was made possible by the development of a new experimental technique. The results presented here suggest that the cut front produced when cutting stainless steel with a fiber laser and a nitrogen assist gas is covered in bumps which themselves are covered in a thin layer of liquid. Under the conditions shown here the bumps move down the cut front at an average speed of approximately 0.4m/s. The liquid flows at an average speed of approximately 1.1m/s. The average melt depth at the bottom of the cut zone under these conditions is approximately 0.17 mm.

In this paper the morphology of the laser cut front generated by fibre lasers was investigated by observation of the ‘frozen’ cut front, additionally high speed imaging (HSI) was employed to study the fluid dynamics on the cut front while cutting. During laser cutting the morphology and flow properties of the melt film on the cut front affect cut quality parameters such as cut edge roughness and dross (residual melt attached to the bottom of the cut edge). HSI observation of melt flow down a laser cutting front using standard cutting parameters is experimentally problematic because the cut front is narrow and surrounded by the kerf walls. To compensate for this, artificial parameters are usually chosen to obtain wide cut fronts which are unrepresentative of the actual industrial process. This paper presents a new experimental cutting geometry which permits HSI of the laser cut front using standard, commercial parameters. These results suggest that the cut front produced when cutting medium section (10 mm thick) stainless steel with a fibre laser and a nitrogen assist gas is covered in humps which themselves are covered by a thin layer of liquid. HSI observation and theoretical analysis reveal that under these conditions the humps move down the cut front at an average speed of approximately 0.4 m/s while the covering liquid flows at an average speed of approximately 1.1 m/s, with an average melt depth at the bottom of the cut zone of approximately 0.17 mm.

This paper investigates the laser piercing process which precedes nearly every laser cutting operation. The two most important aspects of the piercing process are: (a) How long does it take to pierce the material? and (b) How wide is the pierced hole? If the hole is no wider than the cut line, the material can be pierced on the line to be cut. In this paper, 10 mm thick stainless steel was pierced by a multikilowatt fiber laser to compare efficiency and quality when piercing with a continuous wave output and a selected range of power modulation parameters. The different processes were observed by high speed imaging and subsequently examined by visual observation. High speed imaging is used to time the penetration event and to study the laser-material interactions involved in drilling the pierced holes. The results show that appropriate laser power modulation settings can considerably reduce both the piercing time and the required energy to generate any piercing hole required for the subsequent cutting process. This pulse-pierce technique and the differences between piercing with a continuous and a power modulated laser beam are further explained and discussed. Also, the effect on the size of the entrance to the pierced hole depending on power modulation regimes was investigated in this paper.

Before a contour can be laser cut the laser first needs to pierce the material. The time taken to achieve piercing should be minimised to optimise productivity. One important aspect of laser piercing is the reliability of the process because industrial laser cutting machines are programmed for the minimum reliable pierce time. In this work piercing experiments were carried out in 15 mm thick stainless steel sheets, comparing a stationary laser and a laser which moves along a circular trajectory with varying processing speeds. Results show that circular piercing can decrease the pierce duration by almost half compared to stationary piercing. High speed imaging (HSI) was employed during the piercing process to understand melt behaviour inside the pierce hole. HSI videos show that circular rotation of the laser beam forces melt to eject in opposite direction of the beam movement, while in stationary piercing the melt ejects less efficiently in random directions out of the hole.

Cutting fronts created by CO2 and fibre lasers in stainless steel at thicknesses between 2 mm and 10 mm have been ‘frozen’ and their geometry has been measured. Standard commercial cutting parameters were used to generate the cuts for both types of laser. The resulting three-dimensional cutting front shapes have been curve fitted as polynomials and semicircles. Various features of the cutting front geometry are discussed including the lack of correlation of the cut front inclination with either the relevant Brewster angle or the inclination of the striations on the cut edge.

This paper gives the current state of development of laser oxygen and inert gas cuttingfrom experimental results obtained in an industrial environment for a range of materials. The work considers cutting quality as a function of operating parameters. The keyquality parameters are the cut edge inclination, roughness and dross attachment, whilethe kerf width is also studied as an important feature. These parameters are studied asa function of three operating parameters; cutting speed, laser power and laser wavelength. 

Friction stir welding (FSW) and variants of the process have generated high interest in many industries due to its several advantages such as low distortion, superior mechanical properties over arc welding and the possibility of joining dissimilar materials. Increased complexity of industrial applications require a better control of the welding process in order to guarantee a consistent weld quality. This can be achieved by implementing feedback control based on sensor measurements. Previous studies have demonstrated a direct effect of weld temperature on the mechanical properties of FSW joints, [1], and therefore, temperature is chosen as primary process variable in this study.A new method for temperature measurement in FSW referred to as the Tool-WorkpieceThermocouple (TWT) method has recently been developed by De Backer. The TWT method is based on thermoelectric effect and allows accurate, fast and industrially suitable temperature monitoring during welding, without the need for thermocouples inside the tool [2]. This paper presents an application of the TWT method for optimisation of the initial weld phases, plunge and dwell, operation in conventional FSW, which can also be applied to friction stir spot welding (FSSW). An analysis of the operation parameters by using feedback temperature control is presented aiming to better control of the initial weld phases through temperature feedback.

The introduction of the TWT temperature sensor provides additional process information during welding. Fast data acquisition gives opportunity to differentiate different process phases: contact of probe tip with workpiece surface; plunge phase; dwell phase. This would be followed by tool retraction for FSSW or tool traverse phase for FSW.The effect of the plunge parameters on weld temperature and duration of each phase were studied for the purpose of optimising the process with respect to process (i) robustness, (ii)time, (iii) robot deflection and (iv) quality. By using temperature feedback, it is possible to control the plunge phase to reach a predefined weld temperature, avoiding overheating of the material, which is known to have a detrimental influence on mechanical properties. The work presented in this paper is an important step in the optimization of robotic FSSW and FSW.

Friction stir weld (FSW) has generated a high interest in many industry segments in the past 20 years. Along with new industrial challenges, more complex geometries and high quality demands, a better control of the welding process is required. New approaches using temperature controlled welding have been proposed and revealed good results. However, few temperature measurement methods exist which are accurate, fast and industrially suitable. A new and simple sensor solution, the Tool-Workpiece Thermocouple (TWT) method, based on the thermoelectric effect was recently developed.This paper presents a calibration solution for the TWT method where the TWT temperature is compared to calibrated thermocouples inside the tool. The correspondence between both methods is shown. Furthermore, a calibration strategy in different aluminium alloys is proposed, which is based on plunge iterations. This allows accurate temperature monitoring during welding, without the need for thermocouples inside the tool.

Hardware-in-the-loop (HiL) is a concept for testing physical equipment by connecting itto a mathematical representation (model) of the physical process. HiL-testing reduces thecost and saves time before testing the physical equipment (hardware) on the real (physical)process. The physical process chosen for this study is wire+arc additive manufacturing(WAAM), an advanced additive manufacturing (AM) technology that deposits metalbased material layer-by-layer. In this study, simulations of the robot path are carried outwhile the physical robot performs a physical process (additive manufacturing). In robotadditive manufacturing, the desired CAD model is currently sliced down into layers usingslicer software, and the layers are then translated into a path. The robot then moves alongthe path of these pre-defined layers to produce a three-dimensional structure. The heightof the produced structures and desired CAD models have deviations because of processinstabilities and temperature variations among other factors. The robot path should beupdated every time a layer is printed to compensate for the height differences. This isachieved by parametrizing the CAD model, i.e., the CAD model of the structure to beprinted is replaced by a mathematical equation (model). In this study, the mathematicalmodel is updated for each layer in real-time with feedback data from sensors that monitorthe additive manufacturing process. The concept of updating a mathematical model andexecuting it in real-time is called real-time simulation (RTS). In this study, a HiL-basedreal-time simulation setup has been developed, which predicts the required printing layerheight and the number of layers (based upon the latest feedback data from the monitoringsensors), and the required height of the structure. By combining hardware and software,a cyber-physical system has been created, enabling the transition from automation toautonomous robotics and contributing to Industry 4.0. 

This paper reports the tool developments for electrochemical machining (ECM) of precision parts for automotive industry using polymer3D printed inserts. The role of these inserts is to control the fluid flow in the inter-electrode gap as well as to prevent stray machiningby providing insulation. Initial trial and error machining experiments with various tool insert shapes yielded positive outcomes in terms ofcontrolling stray dissolution. It became evident that by 3D printing the entire machining cell structure with integrated, exchangeable toolinserts, all made from polymer, can further enhance the ECM process. This cell-insert assembly enabled better control of the electrochemicaldissolution process and allowed for less restrictive flow of the electrolyte, reducing turbulence in the inter-electrode gap. Thus, by improvingthe electrolyte flow conditions and providing appropriate insulation to prevent stray machining, the 3D printed cell/insert assemblies enabledECM to achieve a shaped profile of an auto engine component to required tolerances.