Lean, Six Sigma ja Total Welding Management hitsaavassa verkostossa

Diplomityössä tarkastellaan hitsaavan verkoston laadunhallintaa ja siinä ilmeneviä erilaisia ongelmakohtia. Tämän lisäksi työssä tarkastellaan kolmen eri laatutyökalun Lean, Six Sigma ja Total Welding Management soveltamista hitsaavan verkoston laadunhallinnassa. Teoriaosassa käsitellään sekä yleisesti että hitsauksen osalta laatua ja laadunhallintaa, sekä edellä mainittuja laatutyökaluja. Tutkimusosaan tietoja hitsaavista verkostoista kerättiin kaikkiaan kolmesta eri verkostosta. Näiden kerättyjen tietojen pohjalta tarkasteltiin valittujen laatutyökalujen soveltuvuutta verkostomaiseen käyttöön. Verkostoitunut toiminta aiheuttaa monia uusia haasteita yritysten laadunhallinnalle verrattuna yksittäisiin hitsaaviin yrityksiin. Suurimpia tutkimuksessa havaittuja ongelmakohtia ovat suunnittelun ja valmistuksen yhteistyön erilaiset puutteet, laatutasoon ja sen varmistukseen liittyvät asiat, sekä verkoston sisälle syntyvä niin sanottu hiljainen tieto ja sen häviäminen. Tutkimuksen tarkastelujen perusteella havaittiin, että kaikkien tutkimukseen valitun kolmen laatutyökalun soveltaminen myös verkostomaisessa toiminnassa on mahdollista, mutta se vaatii huomattavasti suurempaa työpanosta kuin soveltaminen yksittäisessä yrityksessä. Myös näiden kaikkien kolmen työkalun yhtä aikainen käyttö on mahdollista. Juuri oikean työkalun valitseminen kullekin hitsaavalle verkostolle vaatii tarkkaa perehtymistä verkostoon ja sen tilanteeseen.

Laatu ja tuottavuus hitsaavassa verkostossa

Diplomityössä tarkastellaan laadun ja tuottavuuden parantamisen keinoja hitsaavassa verkostossa MIG/MAG-hitsauksen osalta. Työn taustalla vaikuttaa Total Welding Management -menetelmä, mikä on hitsaustoimintojen kokonaisvaltaiseen johtamiseen ja hallintaan kehitetty toimintamalli. Työn teoriaosassa käsitellään laatuajattelua ja yritysyhteistyötä hitsaavan teollisuuden yrityskentässä sekä hitsauskustannuksiin vaikuttavia tekijöitä. Tutkimusosuus sisältää yritysverkoston nykytilan tarkastelun sekä kehitystoimenpiteitä kohti verkoston yhteistä toimintamallia saavuttaa tehokas ja kannattava yhteistyö. Hitsaustyön kustannukset määritetään suurelta osin suunnittelussa. Laatuun voidaan vaikuttaa merkittävästi hitsaustyötä edeltävissä toiminnoissa sekä hitsaajan työn tukemisella. Kokonaisvaltaisen hyödyn saavuttaminen hitsaustyön tuottavuuden parantamisessa vaatii kaikkien toimintojen tarkastelua sen sijaan, että tehostetaan vain hitsaamon toimintaa. Itse hitsaus voi olla vain pieni osa hitsaustoimintojen kokonaishallintaa. Toimintamallin luominen laadunvarmistukseen, suunnittelun ja valmistuksen yhteistyöhön sekä hitsaustoimintojen hallintaan mahdollistaa hitsaavan verkoston toiminnan tehostamisen sekä laadun paranemisen. Tämä saavutetaan viemällä toimintamalli osaksi jokapäiväistä työtä, lähelle valmistusta, ja ohjeistamalla, että jokainen tietää kuinka toimia. Esimerkiksi työssä tarkastellun yhden tuotteen osalta ohjeistus turhan työn vähentämiseksi tuotti 19 % tuotannon kasvun työvuoron aikana. Tilaus-toimitusketjun tuottavuuteen ja kannattavuuteen voidaan vaikuttaa merkittävästi käymällä läpi konkreettisesti valmistettavat tuotteet ja niihin liittyvät toiminnot. Diplomityössä tehtyjen tarkastelujen ja havaintojen avulla käytännön työ tulee jatkumaan yritysverkostossa tapahtuvassa kehitystyössä.

Controlling full penetration in MAG welding by the application of infrared thermography and neural network

In this study, an infrared thermography based sensor was studied with regard to usability and the accuracy of sensor data as a weld penetration signal in gas metal arc welding. The object of the study was to evaluate a specific sensor type which measures thermography from solidified weld surface. The purpose of the study was to provide expert data for developing a sensor system in adaptive metal active gas (MAG) welding. Welding experiments with considered process variables and recorded thermal profiles were saved to a database for further analysis. To perform the analysis within a reasonable amount of experiments, the process parameter variables were gradually altered by at least 10 %. Later, the effects of process variables on weld penetration and thermography itself were considered. SFS-EN ISO 5817 standard (2014) was applied for classifying the quality of the experiments. As a final step, a neural network was taught based on the experiments. The experiments show that the studied thermography sensor and the neural network can be used for controlling full penetration though they have minor limitations, which are presented in results and discussion. The results are consistent with previous studies and experiments found in the literature.

MODELLING AND CONTROL OF ERSW PROCESSES BY NEURONAL NETWORK

A study on the use of artificial intelligence (AI) techniques for the modelling and subsequent control of an electric resistance spot welding process (ERSW) is presented. The ERSW process is characterized by the coupling of thermal, electrical, mechanical, and metallurgical phenomena. For this reason, early attempts to model it using computational methods established as the methods of finite differences, finite element, and finite volumes, ask for simplifications that lead the model obtained far from reality or very costly in terms of computational costs, to be used in a real-time control system. In this sense, the authors have developed an ERSW controller that uses fuzzy logic to adjust the energy transferred to the weld nugget. The proposed control strategies differ in the speed with which it reaches convergence. Moreover, their application for a quality control of spot weld through artificial neural networks (ANN) is discussed.

Advanced orbital pipe welding

Since the introduction of automatic orbital welding in pipeline application in 1961, significant improvements have been obtained in orbital pipe welding systems. Requirement of more productive welding systems for pipeline application forces manufacturers to innovate new advanced systems and welding processes for orbital welding method. Various methods have been used to make welding process adaptive, such as visual sensing, passive visual sensing, real-time intelligent control, scan welding technique, multi laser vision sensor, thermal scanning, adaptive image processing, neural network model, machine vision, and optical sensing. Numerous studies are reviewed and discussed in this Master’s thesis and based on a wide range of experiments which already have been accomplished by different researches the vision sensor are reported to be the best choice for adaptive orbital pipe welding system. Also, in this study the most welding processes as well as the most pipe variations welded by orbital welding systems mainly for oil and gas pipeline applications are explained. The welding results show that Gas Metal Arc Welding (GMAW) and its variants like Surface Tension Transfer (STT) and modified short circuit are the most preferred processes in the welding of root pass and can be replaced to the Gas Tungsten Arc Welding (GTAW) in many applications. Furthermore, dual-tandem gas metal arc welding technique is currently considered the most efficient method in the welding of fill pass. Orbital GTAW process mostly is applied for applications ranging from single run welding of thin walled stainless tubes to multi run welding of thick walled pipes. Flux cored arc welding process is faster process with higher deposition rate and recently this process is getting more popular in pipe welding applications. Also, combination of gas metal arc welding and Nd:YAG laser has shown acceptable results in girth welding of land pipelines for oil and gas industry. This Master’s thesis can be implemented as a guideline in welding of pipes and tubes to achieve higher quality and efficiency. Also, this research can be used as a base material for future investigations to supplement present finding.

Quality, Productivity and Economy in Welding Manufacturing - Case Study: West Africa

This thesis studies quality, productivity and economy in welding manufacturing in West African states such as Ghana, Nigeria and Cameroon. The study consists of two parts: the first part, which forms the theoretical background, reviews relevant literature concerning the metal and welding industries, and measurement of welding quality, productivity and economy. The second part, which is the empirical part, aims to identify activities in the metal manufacturing industries where welding is extensively used and to determine the extent of welding quality, productivity and economy measurements in companies operating in the metal manufacturing industries. Additionally, the thesis aims to identify challenges that companies face and to assess the feasibility of creating a network to address these issues. The research methods used in the empirical part are the case study (qualitative) method and the survey (quantitative) method. However, the case study method was used to elicit information from companies in Ghana, while the survey method was used to elicit information from companies in Nigeria and Cameroon. The study considers important areas that contribute to creating awareness and understanding of the current situation of the welding industry in West Africa. These areas include the metal manufacturing industrial sector, metal products manufactured, metal production and manufacturing systems deployed, welding quality, productivity and economy measurement systems utilized, equipment and materials on the markets, general challenges facing companies in welding operations, welding technology programs and research in local universities, and SWOT analysis of the various West African states. The notable findings indicate that majority of the companies operate in the constructionindustrial sector. Also, majority of the companies are project manufacturing oriented, thus provide services to customers operating in the growing industries such as the oil and gas, mining, food and the energy industry. In addition, only few companies are certified under standards such as ISO 9001, ISO 3834, and OHSAS 18001. More so, majority of the companies employ manual welding technique, and shielded metal arc welding (SMAW) as the commonly used welding process. Finally, welder salary is about € 300 / month as of June 2013 and the average operations turnover of medium to large companies is about € 5 million / year as at 2012. Based on analysis of the results of the study, it is noted that while welding activities are growing, the availability of cheap labor, the need for company and welder qualification and certification, and the need to manufacture innovative products through developmental projects (transfer of welding expertise and technology) remain as untapped opportunities in the welding industry in the West African states. The study serves as a solid platform for further research and concludes with several recommendations for development of the West African welding industry.

Underwater Remote Welding Technology for Offshore Structures

The construction of offshore structures, equipment and devices requires a high level of mechanical reliability in terms of strength, toughness and ductility. One major site for mechanical failure, the weld joint region, needs particularly careful examination, and weld joint quality has become a major focus of research in recent times. Underwater welding carried out offshore faces specific challenges affecting the mechanical reliability of constructions completed underwater. The focus of this thesis is on improvement of weld quality of underwater welding using control theory. This research work identifies ways of optimizing the welding process parameters of flux cored arc welding (FCAW) during underwater welding so as to achieve desired weld bead geometry when welding in a water environment. The weld bead geometry has no known linear relationship with the welding process parameters, which makes it difficult to determine a satisfactory weld quality. However, good weld bead geometry is achievable by controlling the welding process parameters. The doctoral dissertation comprises two sections. The first part introduces the topic of the research, discusses the mechanisms of underwater welding and examines the effect of the water environment on the weld quality of wet welding. The second part comprises four research papers examining different aspects of underwater wet welding and its control and optimization. Issues considered include the effects of welding process parameters on weld bead geometry, optimization of FCAW process parameters, and design of a control system for the purpose of achieving a desired bead geometry that can ensure a high level of mechanical reliability in welded joints of offshore structures. Artificial neural network systems and a fuzzy logic controller, which are incorporated in the control system design, and a hybrid of fuzzy and PID controllers are the major control dynamics used. This study contributes to knowledge of possible solutions for achieving similar high weld quality in underwater wet welding as found with welding in air. The study shows that carefully selected steels with very low carbon equivalent and proper control of the welding process parameters are essential in achieving good weld quality. The study provides a platform for further research in underwater welding. It promotes increased awareness of the need to improve the quality of underwater welding for offshore industries and thus minimize the risk of structural defects resulting from poor weld quality.

Structural Connectivity Of The Default Mode Network And Cognition In Alzheimer׳s Disease.

Disconnectivity between the Default Mode Network (DMN) nodes can cause clinical symptoms and cognitive deficits in Alzheimer׳s disease (AD). We aimed to examine the structural connectivity between DMN nodes, to verify the extent in which white matter disconnection affects cognitive performance. MRI data of 76 subjects (25 mild AD, 21 amnestic Mild Cognitive Impairment subjects and 30 controls) were acquired on a 3.0T scanner. ExploreDTI software (fractional Anisotropy threshold=0.25 and the angular threshold=60°) calculated axial, radial, and mean diffusivities, fractional anisotropy and streamline count. AD patients showed lower fractional anisotropy (P=0.01) and streamline count (P=0.029), and higher radial diffusivity (P=0.014) than controls in the cingulum. After correction for white matter atrophy, only fractional anisotropy and radial diffusivity remained significantly lower in AD compared to controls (P=0.003 and P=0.05). In the parahippocampal bundle, AD patients had lower mean and radial diffusivities (P=0.048 and P=0.013) compared to controls, from which only radial diffusivity survived for white matter adjustment (P=0.05). Regression models revealed that cognitive performance is also accounted for by white matter microstructural values. Structural connectivity within the DMN is important to the execution of high-complexity tasks, probably due to its relevant role in the integration of the network.

Can We Predict The Clinical Outcomes Of Genitourinary Trauma Patients And Offer Them An Evidence-based Support? The Case For Telemedicine Network.

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[gait Speed, Grip Strength And Self-rated Health Among The Elderly: Data From The Fibra Campinas Network, São Paulo, Brazil].

The article seeks to investigate patterns of performance and relationships between grip strength, gait speed and self-rated health, and investigate the relationships between them, considering the variables of gender, age and family income. This was conducted in a probabilistic sample of community-dwelling elderly aged 65 and over, members of a population study on frailty. A total of 689 elderly people without cognitive deficit suggestive of dementia underwent tests of gait speed and grip strength. Comparisons between groups were based on low, medium and high speed and strength. Self-related health was assessed using a 5-point scale. The males and the younger elderly individuals scored significantly higher on grip strength and gait speed than the female and oldest did; the richest scored higher than the poorest on grip strength and gait speed; females and men aged over 80 had weaker grip strength and lower gait speed; slow gait speed and low income arose as risk factors for a worse health evaluation. Lower muscular strength affects the self-rated assessment of health because it results in a reduction in functional capacity, especially in the presence of poverty and a lack of compensatory factors.

Going Beyond Seizure Control: Can Pharmacotherapy Help To Restore Cognitive Network Function?

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Whole Cortical And Default Mode Network Mean Functional Connectivity As Potential Biomarkers For Mild Alzheimer's Disease.

The search for an Alzheimer's disease (AD) biomarker is one of the most relevant contemporary research topics due to the high prevalence and social costs of the disease. Functional connectivity (FC) of the default mode network (DMN) is a plausible candidate for such a biomarker. We evaluated 22 patients with mild AD and 26 age- and gender-matched healthy controls. All subjects underwent resting functional magnetic resonance imaging (fMRI) in a 3.0 T scanner. To identify the DMN, seed-based FC of the posterior cingulate was calculated. We also measured the sensitivity/specificity of the method, and verified a correlation with cognitive performance. We found a significant difference between patients with mild AD and controls in average z-scores: DMN, whole cortical positive (WCP) and absolute values. DMN individual values showed a sensitivity of 77.3% and specificity of 70%. DMN and WCP values were correlated to global cognition and episodic memory performance. We showed that individual measures of DMN connectivity could be considered a promising method to differentiate AD, even at an early phase, from normal aging. Further studies with larger numbers of participants, as well as validation of normal values, are needed for more definitive conclusions.

[strategies For Integration Of Health Care Practices And Sanitary Surveillance In The Context Of The Implementation Of Rede Cegonha - A Brazilian Mother And Infant Health Care Network].

Mother and infant mortality has been the scope of analysis throughout the history of public health in Brazil and various strategies to tackle the issue have been proposed to date. The Ministry of Health has been working on this and the Rede Cegonha strategy is the most recent policy in this context. Given the principle of comprehensive health care and the structure of the Unified Health System in care networks, it is necessary to ensure the integration of health care practices, among which are the sanitary surveillance actions (SSA). Considering that the integration of health care practices and SSA can contribute to reduce mother and infant mortality rates, this article is a result of qualitative research that analyzed the integration of these actions in four cities in the State of São Paulo/Brazil: Campinas, Indaiatuba, Jaguariúna and Santa Bárbara D'Oeste. The research was conducted through interviews with SSA and maternal health managers, and the data were evaluated using thematic analysis. The results converge with other studies, identifying the isolation of health care practices and SSA. The insertion of SSA in collectively-managed areas appears to be a potential strategy for health planning and implementation of actions in the context under scrutiny.

[child Protection Network And The Intersector Implementation Of The Circle Of Security As Alternatives To Medication].

To describe the clinical history of a child with aggressive behavior and recurring death-theme speech, and report the experience of the team of authors, who proposed an alternative to medication through the establishment of a protection network and the inter-sector implementation of the circle of security concept. A 5-year-old child has a violent and aggressive behavior at the day-care. The child was diagnosed by the healthcare center with depressive disorder and behavioral disorder, and was medicated with sertraline and risperidone. Side effects were observed, and the medications were discontinued. Despite several actions, such as talks, teamwork, psychological and psychiatric follow-up, the child's behavior remained unchanged. A unique therapeutic project was developed by Universidade Estadual de Campinas' Medical School students in order to establish a connection between the entities responsible for the child's care (daycare center, healthcare center, and family). Thus, the team was able to develop a basic care protection network. The implementation of the inter-sector circle of security, as well as the communication and cooperation among the teams, produced very favorable results in this case. This initiative was shown to be a feasible and effective alternative to the use of medication for this child.

[access To Information About How To Prevent Oral Problems Among School Children In The Public School Network].

The scope of this study is to identify the prevalence of access to information about how to prevent oral problems among schoolchildren in the public school network, as well as the factors associated with such access. This is a cross-sectional and analytical study conducted among 12-year-old schoolchildren in a Brazilian municipality with a large population. The examinations were performed by 24 trained dentists and calibrated with the aid of 24 recorders. Data collection occurred in 36 public schools selected from the 89 public schools of the city. Descriptive, univariate and multiple analyses were conducted. Of the 2510 schoolchildren included in the study, 2211 reported having received information about how to prevent oral problems. Access to such information was greater among those who used private dental services; and lower among those who used the service for treatment, who evaluated the service as regular or bad/awful. The latter use toothbrush only or toothbrush and tongue scrubbing as a means of oral hygiene and who reported not being satisfied with the appearance of their teeth. The conclusion drawn is that the majority of schoolchildren had access to information about how to prevent oral problems, though access was associated with the characteristics of health services, health behavior and outcomes.