Academic literature on the topic 'Six sigma concept'

Thesis (MScEng)--University of Stellenbosch, 2005.<br>ENGLISH ABSTRACT: This report presents the application of the six sigma quality concept in solving a true business problem. Six sigma is a quality improvement and business strategy/tool developed by Motorola in the mid 1980s. It aims at delivering products and services that approach levels of near perfection. To achieve this objective a six sigma process must not produce more than 3.4 defects per million opportunities, meaning the process should be at least 99.9997% perfect [Berdebes, 2003]. Motorola's success with six sigma popularised the concept and it has now been adopted by many of the world's top compames e.g. General Electric, Allied Signal-Honeywell, etc. All the six sigma companies report big financial returns as a result of increased quality levels due to the reduction in the number of defects. 'General Electric reports annual benefits of over $2.5 billion across the organisation from six sigma' [Huag, 2003]. The six sigma concept follows a five step problem-solving methodology known as DMAIC (Define, Measure, Analyse, Improve, Control) to improve existing processes. Each of these steps makes use of a range of tools, which include quality, statistical, engineering, and business tools. This report first gives a theoretical presentation on quality and six sigma, attempting to answer the question 'What is six sigma'. A step-by-step guide on how to go through the DMAIC problem solving cycle is also presented. The six sigma concept was demonstrated by application to the colour removal process of a continuous processing plant manufacturing refined sugar. Colour removal is a very important process in sugar refining since the purpose of a refinery is to remove colour and other impurities from the raw sugar crystals. The colour removal process consists of three unit operations; liming, carbonation and sulphitation. Liming involves the addition of lime (calcium hydroxide) required for the formation of a calcium precipitate in the next unit operations. Carbonation is carried out in two stages; primary and secondary carbonation. Both stages involve the formation of a calcium carbonate precipitate, which traps colour bodies and other impurities. Sulphitation occurs in a single step and involve the formation of a calcium sulphite precipitate which also traps impurities. The pH and colour are the main variables that are being monitored throughout the colour removal process. Colour removal process Raw sugar Melting Carbonation Crystalli ~ Liming ~ c::J Secondary f+ Sulphitation .. Sugar sation Figure 1: Colour removal process The pH control of the two colour removal unit operations; carbonation and sulphitation, is very poor and as a result the colour removal achieved is below expectation. This compromises the final refined sugar quality since colour not removed in the colour removal processes ends up in the sugar. The first carbonation stage (primary) fails to lower the pH to the required specification and the second carbonation stage (secondary) is highly erratic, the pH fluctuating between too high and too low. The sulphitation process adds more sulphur dioxide than required and hence the pH is lowered below the lower specification limit. The six sigma DMAIC cycle was implemented in order to solve the problem of poor pH control. The Define phase defined the project and identified the process to be improved. The Measure phase measured the current performance of the process by collecting past laboratory data with the corresponding field instruments data. The data was used to draw frequency distribution plots that displayed the actual variation of the process relative to the natural variation of the process (specification width) and to calculate process capability indices. The Analyse phase analysed the data so as to determine the key sources of variation. The Improve phase used the findings of the analyse phase to propose solutions to improve the colour removal processes. The Control phase proposed a control plan so as to monitor and sustain the improvement gained. The key findings of the study are presented below: • Failure of the first carbonation stage to lower the pH to the required level is due to insufficient carbon dioxide gas supply. • The second carbonation reaction occurs very fast hence poor control will result in high variability. • The amount of colour removed is dependent on the input raw melt colour. • The histograms of the colour removal unit operations are off-centered and display a process variation greater than the specification width and hence a large proportion of the data falls outside the specification limits. • The % CaO and CO2 gas addition were found to be the key variables that control the processes centering on target. The % CaO having a stronger effect in the liming process and CO2 gas addition on the carbonation process. • The variation between the field instrument's pH and laboratory pH is the key variable that control the processes spread (standard deviation of the processes). • The processes Cpk values are less than C, (Cpk<Cp) meaning the processes can be improved by controlling the key variables that control centering (% CaO, CO2 gas addition). The processes capability indices are low, Cp<l meamng the processes are not statistically capable of meeting the required specifications at the current conditions. • Based on the findings of the study, the following deductions are made for the improvement of the colour removal processes in better meeting the required specifications. • Increase the CO2 gas supply to at least 4900 m31hr, calculated based on the fact that at least 140 rrr' gas is required per ton of solids in melt [Sugar Milling Research Institute Course Notes, 2002]. • Control the key variables identified to be the key sources of variation; % CaO, CO2 gas addition and variation between the field instrument's pH and laboratory pH. Reducing variation in the % CaO and increasing CO2 gas supply will improve the processes ability to maintain centering at the target specification. Maintaining a consistent correlation between the two pH readings; field instruments pH and laboratory pH will reduce the processes standard deviation and hence the processes spread. Reduction in the processes spread will minimize the total losses outside the specification limits. This will allow better control of the pH by getting rid of high fluctuations. • Control of the input raw melt colour is essential since it has an impact on the degree of decolourisation. The higher the input colour, the more work required in removing the colour. In improving the colour removal processes the starting point should be in ensunng process stability. Only once this is achieved, the above adjustments may be made to improve the processes capability. The processes capability will only improve to a certain extent since from the capability studies it is evident that the processes are not capable of meeting specifications. To provide better control and to ensure continuous improvement of the processes the following recommendations are made: • Statistical process control charts The colour removal processes are highly unstable, the use of control charts will help in detecting any out of control conditions. Once an out of control condition has been detected, necessary investigations may be made to determine the source of instability so as to remove its influence. Being able to monitor the processes for out of control situations will help in rectifying any problems before they affect the processes outputs. • Evaluation of capability indices- ISO 9000 internal audits Consider incorporating the assessment of the capability indices as part of the ISO 9000 internal audits so as to measure process improvement. It is good practice to set a target for Cp, the six sigma standard is Cp=2, this however does not mean the goal should be Cp=2 since this depends on the robustness of the process against variation. For instance the colour removal processes at the current operating conditions can never reach Cp=2. This however is not a constraint since for the colour removal processes to better meet pH specifications it is not critical that they achieve six sigma quality. A visible improvement may be seen in aiming for Cp=I. On studying the effects of CO2 gas addition the total data points outside specification limits reduced from 84 % to 33 % and by reducing the variation between field instruments pH and laboratory pH for the secondary pH the total data points out of specification reduced from 55 % to 48 %. These results indicate that by improving C, to be at least equal to one (Cp=l) the total data points outside specification can reduce significantly, indicating a high ability of the processes to meet specifications. Thus even if six sigma quality is not achieved, by focussing on process improvement using six sigma tools visible benefits can be achieved.<br>AFRIKAANSE OPSOMMING: Hierdie tesis kyk na die toepassing van die ses sigma kwaliteitskonsep om 'n praktiese probleem op te los. Ses sigma soos dit algemeen bekend staan is nie slegs 'n kwaliteitverbeteringstegniek nie maar ook 'n strategiese besigheidsbenadering wat in die middel 1980s deur Motorolla ontwikkel en bekend gestel is. Die doelstellings is om produkte en dienste perfek af te lewer. Om die doelwit te kan bereik poog die tegniek om die proses so te ontwerp dat daar nie meer as 3.4 defekte per miljoen mag wees nie - dit wil se die proses is 99,9997% perfek [Berdebes, 2003]. As gevolg van die sukses wat Motorolla met die konsep behaal het, het dit algemene bekendheid verwerf, en word dit intussen deur baie van die wereld se voorste maatskappy gebruik, o.a. General Electric, Allied Signal-Honeywell, ens. Al die maatskappye toon groot finansele voordele as gevolg van die vermindering in defekte wat teweeg gebring is. So by. beloop die jaarlikse voordele vir General Electric meer as $2.5 biljoen [Huag, 2003]. Die ses sigma konsep volg 'n vyf-stap probleem oplossings proses (in Engels bekend as DMAIC: Define, Measure, Analyse, Improve, Control), naamlik definieer, meet, analiseer, verbeter, en beheer om bestaande prosesse te verbeter. In elkeen van die stappe is daar spesifieke gereedskap oftegnieke wat aangewend kan word, soos by. kwaliteits-, statistiese--, ingenicurs-cn besigheids tegnieke. Die verslag begin met 'n teoretiese oorsig oor kwaliteit en die ses sigma proses, waardeur die vraag "wat is ses sigma" beantwoord word. Daama volg 'n gedetailleerde stap-virstap beskrywing van die DMAIC probleem oplossingsiklus. Die toepassing van die ses sigma konsep word dan gedoen aan die hand van 'n spesifieke proses in die kontinue suiker prosesserings aanleg, naamlik die kleurverwyderingsproses. Hierdie proses is baie belangrik omdat die doelstellings daarvan juis draai rondom die verwydering van nie net kleur nie maar ook alle ander vreemde bestanddele van die rou suiker kristalle. Die proses bestaan uit drie onafhanklike maar sekwensiele aktiwiteite waardeur verseker word dat die regte gehalte suiker uiteindelik verkry word. Tydens die eerste twee stappe is veral die pH-beheer onder verdenking, sodat die kleur verwydering nie die gewenste kwaliteit lewer nie. Dit bemvloed op sy beurt die gehalte van die finale produk, omdat die ongewenste kleur uiteindelik deel is van die suiker. Die pH inhoud is nie net nie laag genoeg nie, maar ook hoogs veranderlik - in beginsel dus buite beheer. Die DMAIC siklus is toegepas ten einde die pH beter te kan beheer. Tydens die definisiefase is die projek beskryf en die proses wat verbeter moet word identifiseer. In die meetfase IS die nodige data versamel om sodoende die inherente prosesveranderlikheid te bepaal. Die belangrikste bronne of veranderlikes wat bydra tot die prosesveranderlikheid is in die derde-- of analisefase bepaal. Hierdie bevindings is gebruik tydens die verbeteringsfase om voorstelle ter verbetering van die proses te maak. Die voorstelle is implementeer en in die laaste fase, naamlik die beheerfase, is 'n plan opgestel ten einde te verseker dat die proses deurentyd gemonitor word sodat die verbeterings volhoubaar bly. 'n Hele aantal veranderlikes wat elk bygedra het tot die prosesvariasie is identifiseer, en word in detail in die verslag beskryf. Gebaseer op die analise en bevindings van die ondersoek kon logiese aanbevelings gemaak word sodat die proses 'n groot verbetering in kleurverwydering getoon het. Die belangrikste bevinding was dat die huidige proses nie die vermoee het om 100% te voldoen aan die spesifikasies of vereistes nie. Die hoofdoel van die voorstelle is dus om te begin om die prosesveranderlikheid te minimeer of ten minste te stabiliseer - eers nadat die doel bereik is kan daar voortgegaan word om verbeteringe te implementeer wat die prosesvermoee aanspreek. Ten einde hierdie beheer te kan uitoefen en vanasie te verminder IS die volgende voorstelle gemaak: Statistiese beheer kaarte Die kleurverwyderingsproses is hoogs onstabiel. Met behulp van statistiese beheer kaarte is daar 'n vroegtydige waarskuwing van moontlike buite beheer situasies. Die proses kan dus ondersoek en aangepas word voordat die finale produkkwaliteit te swak word. • Evaluering van proses vermoee - ISO 9000 interne oudit Die assesering van die prosesvermoee behoort deel te word van die interne ISO oudit proses, om sodoende prosesverbeteringe gereeld en amptelik te meet. Die standaard gestel vir C, behoort gedurig aandag te kry - dit is nie goeie praktyk om bv. slegs 'n doelwit van C, = 2 soos voorgestel in ses sigma te gebruik nie, maar om dit aan te pas na gelang van die robuustheid van die proses wat bereik is. Daar is beduidende voordele bereik deur die toepassing van die DMAIC siklus. So het byvoorbeeld die persentasie datapunte buite spesifikasie verminder van 84% tot 33%, bloot deur te kyk na die effek wat die toevoeging van C02 gas tydens die proses het. Dit toon dus duidelik dat, alhoewel die proses huidiglik nie die vermoee het om te voldoen aan die vereistes van ses sigma nie, dit wel die moeite werd is om die beginsels en tegnieke toe te pas.

Ett sätt för företag att öka lönsamhet och behålla marknadsandelar och konkurrenskraft är att ständigt förbättra sina produkter genom systematisk produktutveckling. Alfa Laval AB i Ronneby tillverkar lödda plattvärmeväxlare som förses med skyddslock och/eller skyddspluggar i flera storlekar och varianter under transport. Syftet med studien är därför att optimera skyddet med avseende på arbetsmiljö, miljö, lagerkapacitet och till en likvärdig eller lägre kostnad. Målet är att generera förbättringsförslag som ersätter de nuvarande transportskydden med ett fåtal standardskydd. Studien genomfördes som en fallstudie och följde den ingenjörsvetenskapliga Systems Engineering-metoden Design For Six Sigma (DFSS). DFSS-processen är uppdelad i fyra steg för att på ett systematiskt sätt uppnå önskat resultat och generera förbättringsförslag till fallföretaget. Studien resulterade i ett förbättringsförslag i form av en krympfilm som ersättande transportskydd. Förbättringsförslaget genererade även en reducering av antal storlekar och varianter med 80 %, vilket i sin tur reducerade lagernivåer.<br>One way for companies to increase profitability and maintain market shares and competitiveness is to constantly improve their products through systematic product development. Alfa Laval AB in Ronneby manufactures soldered plate heat exchangers which are provided with protective covers and/or protective plugs in several sizes and variants during transport. The purpose of this study is, therefore, to optimize the protection with regard to the work environment, environment, storage capacity and at an equivalent or lower cost. The goal is to generate improvement proposals that replace the current transport protections with a few standard protections. The study was conducted as a case study and followed the Engineering Scientific Systems Engineering method Design For Six Sigma (DFSS). The DFSS process is divided into four steps in order to systematically achieve desired results and generate improvement proposals for the case company. The study resulted in an improvement proposal in the form of a shrink film as a replacement for the transport protection. The improvement proposal also generated a reduction of 80 % in the number of sizes and variants, which in turn reduced stock levels.

Thèse (Ph.D.) -- École de technologie supérieure, Montréal, 2007.<br>"Thesis presented to École de technologie supérieure in partial requirements for the degree of doctor of philosopphy." "by Al Qutaish, Rafa" -- p. de t. CaQMUQET CaQMUQET Bibliogr. : f. [199]-212. Également disponible en version électronique. CaQMUQET

碩士<br>臺灣大學<br>園藝學研究所<br>96<br>The flourishing development of the service industry makes GDP over 73% in recent years. About 58% of the employment population serve this industry. The leisure service industry, in particular grows by multiple revealing its significant importance. As there is a feature of high homogeneity and substitution in the same trade, the core issue lies on enhancement of service quality in an environment of keen competition. As a result, six sigma (6σ) is applied in this research to improve service quality and increase competitiveness of the leisure industry. First, the service quality model proposed by Parasuraman, Zeithaml and Berry (PZB model for short) is utilized to design the items in the service quality questionnaire. Importance and satisfaction of each service item perceived by customers are based for the scale, whose means are further converted to indexes. Thus, a scale-based service performance evaluation matrix with indices of importance as the Y-axis and those of satisfaction as the X-axis is defined. Then, service factors of high importance and low satisfaction are located and defined for improvement in accordance with the index location of each service factor. A measurement model based on the difference between customers’ importance and satisfaction is proposed and a measurement index is defined for an objective evaluation method and procedures. Next, factors of customer dissatisfaction are analyzed and improvement methods are devised. Finally, herb garden service quality is monitored by the performance control model. This paper is a case study on a herb garden A, located at so called Herb Township（Shinshou Township） in Taichung County. Comparisons were made with the other two herb gardens B and C, their locations are close to A, to identify crucial problems clearly and positively expressed by customer. For the survey, a total of 330 copies of questionnaire were issued where 289 were effective copies; 96 were from A, 93 from B and 100 from C, respectively. Survey was made from 2007/7/1 to 2007/7/22. The questionnaires were compared using the performance evaluation matrix and the distance far away from the expected results. The 16th service item： the detailed explanations of the herb characteristic, culture, function and application , was identified to be the crucial problems of herb garden A . It is necessary to be improved first . The cause and effect diagram presented is used to analyze major factors of customer dissatisfaction and improvement strategies are devised by the correlation coefficient matrix. After the improvement strategy, the herb garden A is requested to carry out the crucial strategy to give the detail explanations on improvements on herb characteristic, culture, function and application. For this research, questionnaires were issued once on 2007/11/24 with 49 effective returns. The calculated K value after improvement is shown to drop from 2.092 to 1.051. This value is found to be in the acceptance area. After implementing the related improvement strategies and with a low K value, customer importance and customer satisfactions are increasingly closer. So after finding an abnormal product service and changes made in an ideal range, the herb garden A can then follow the standardized procedure and knowledge management to implement which can ensure effective control. After these analysis and research, the standard performance evaluation was developed suitable for the herb garden service industry which can be used to maintain and control service quality. This will increase competitiveness in face of fierce competitions in the near future. At the same time, the improvements also made the herb gardener to achieve and to match standardized procedures used in horticultures for successful management.

碩士<br>國立雲林科技大學<br>資訊管理系碩士班<br>91<br>Along with the development of the Internet and the trend of globalization, the Supply Chain Management has been used even wider in the world. However, one problem brought to our attention is that the evaluation of performance always lacks structured procedures. Hakan & Pia(2002) has discussed the Six Sigma as a company-wide approach for organizational improvement which is incorporated with organizational learning. As a result, we try to include the procedures of Six Sigma and the operation of 2-Tuples Fuzzy Linguistic Label in this study to calculate the weight of performance by the expert questionnaire. Through the structured procedures, we can find more efficient evaluation rules; furthermore, a Supply Chain Management Performance Decision Support System can be established. The contribution in this paper include: 1. Widen the meaning of DMAIC management as one of the steps of Supply Chain Management Performance evaluation, and make the performance evaluation to be more systematized and structured. 2. Through the literature review, we sum up five constructs and thirty-six key factors in the Supply Chain Management performance evaluation. 3. The 2-Tuples Fuzzy Linguistic Label not only overcomes the unclosed problem of two dimensions fuzzy execution but also makes the questionnaire friendlier for surveyor. 4. In software system development, we use web-based interface to design Decision Support System. On the basis of this, experts not only be able to answer and evaluate the questionnaires via the internet but follow the 2-Tuples Fuzzy Linguistic Label to evaluate the company’s performance. 5. The expert’s opinions have key effects about the evaluation factors in this paper. Accordingly, we have more objective and righteous criteria about the qualifications of experts. At the same time, we not only choose senior scholars but also include the professional that have sufficient experiences in management field. According to this, we reach a harmony between academic and practical world. 6. We obtain answers from the case study, the results from the algorithm of performance evaluation of electronic Supply Chain Management have its rationality and adaptability.

碩士<br>國立屏東科技大學<br>企業管理研究所<br>95<br>The organization can survive forever based on Customer satisfaction which creates profits from value creation. How to increase the value and decrease the cost is an important task of an organization. Thus to build a value chain combines with customer-orientation will create competitive advantage.Processes are increasingly being seen as the way to organize firms, versus by function. One of the biggest advantages of focusing on processes, rather than functions, is that processes enable the organization to focus on the customer. Many researches emphasized the importance of organizations properly redesigning their processes and structures, so that they will become more efficient with higher yield, better quality and lower cost. The scholars also indicated that process re-engineering obtains dramatic and sustainable improvements in time, cost, resources, etc. This study takes a national manufacturing plant’s strategy of production performance promotion as an example to do the research, and starts it from survey and analysis on current performance indicators’ setting of production and combines with both theory and establishes three dimensions’ analysis and comparisons, including “implications of performance indicator”, “covering percentage of value chain” and “degree of customer-oriented” which are quantified and qualified relatively and separately. This analysis and comparisons can be utilized to investigate the effectiveness of working procedures, focus on routine jobs, the capabilities of value creation and self-driven mechanism of members of production department. This study uses the DMAIC (Define-Measure-Analysis-Improve-Control) cycle to deploy the re-engineering activities. The main purpose is to work out a strategy in integrating all internal and external customers’ output and feedback so as to promote production performance. Finally, interviews in-depth have been performed with four companies in industries. It is highly convinced the analysis and comparisons being applied in process re-engineering strategy can be beneficial for manufacturer’s driving quality improvements and promoting production performance.

With the rapid growth in the hospitality industry, its owners and managers are also facing serious challenges. The industry is becoming more and more competitive. Managers are pressed to find the balance between cutting cost to increase profit and improving the quality of the service/product to increase the value their customers’ experience. Customers are nowadays more aware of the quality of the service or the product provided to them and more than ever before, hospitality owners and managers need to focus on improving their quality. The main objective of the research was to establish whether the implementation of selected Six Sigma principles would result in a measurable improvement in the quality of a hospitality establishment. An analysis was done based on three different feedback systems, some Sig Sigma-inspired changes were made and a post-measurement was done to establish the effect of the changes. The study concluded that the implementation of selective Six Sigma principles, can improve the quality of services and products in hospitality establishments, as well as reducing their process waste in such establishments.<br>MBA, North-West University, Potchefstroom Campus, 2015

Transformation is change—especially under challenging circumstances—that is significant, systematic, and sustained, resulting in high levels of achievement for all students in all settings (Caldwell, 2006). Urban education is the primary focus and target of the school reform movement. The No Child Left Behind Act (NCLB) includes explicit requirements to ensure that students served by Title I are given the same opportunity achieve to high standards and are held to the same high expectations as all other students in each state. Urban public school superintendents confront social and economic challenges unique to urban districts and are under pressure to meet NCLB’s accountability standards and mandated policies. This study started with a broad question about effective urban public school superintendent management concepts and strategies. The study was designed and conducted to (a) identify the prevailing management concepts and strategies initiated by the superintendent to attain organizational clarity and effectiveness in improving student performance; (b) examine the degree to which the superintendent’s leadership and management concepts and strategies were understood, supported, and embraced by key members of the organization; and (c) examine how the management concepts and strategies used by the superintendent align with a business management concept that may be useful to district leaders and administrators seeking a concept or strategy to sustain organizational change. This researcher used a single-case study to examine the management concepts and strategies used by an urban public school district superintendent. This study was conducted in the largest urban public school system in Texas. The superintendent, 6 members of the district’s leadership team, and five principals were interviewed and answered online questionnaires. A board member was also interviewed. Finally, student achievement data were examined. The study found the superintendent implemented management leadership concepts and strategies that prevailed over the social and economic barriers faced by urban students. Use of these strategies increased and sustained student performance. Despite limitations, this study opens opportunities for further research in management leadership. Opportunities include further research within this urban district, outside the school district, or on each management leadership concept or strategy identified in this study.<br>text