D
IPARTIMENTO DII
NGEGNERIA DELL’E
NERGIA DEIS
ISTEMI,
DELT
ERRITORIO E DELLEC
OSTRUZIONIRELAZIONE PER IL CONSEGUIMENTO DELLA LAUREA MAGISTRALE IN INGEGNERIA GESTIONALE
Implementation of Operators Manufacturing
Procedures in a SME Foundry
RELATORI IL CANDIDATO
Prof. Ing. Gino Dini Francesco Lischi
Dipartimento di Ingegneria Civile e Industriale francescolischi@hotmail.it
Prof. Mark Jolly
School of Applied Sciences, Cranfield University
Roger Kings
Anno Accademico 2013/2014 Consultazione NON consentita
Francesco Lischi
Sommario
Il settore della fonderia è storicamente associato a cattive pratiche di produzione e povere condizioni di lavoro. Per questo motivo, è essenziale l’implementazione di giuste pratiche di produzione, soprattutto per le PMI che operano in questo settore, vista la loro limitata possibilità di investimento. Il metodo di indagine usato per lo sviluppo di questo progetto, fornisce, a cominciare dall’analisi delle best practices, dei problemi di produzione e degli investimenti, un approccio sistematico per l’implementazione di procedure di produzione rivolte agli operatori di una piccola/media fonderia. In aggiunta, sottolineando continuamente l’importanza di coinvolgere le persone per il successo del progetto, la tesi dimostra come le nuove procedure possano minimizzare i prodotti rilavorati, i relativi costi e il tempo di consegna del prodotto, con il conseguente raggiungimento di un miglior customer service. Per la validazione della metodologia proposta, il progetto, elaborato come Individual Project alla Cranfield University, è stato sviluppato con J H Richards, una piccola azienda inglese a gestione familiare che produce e ripara cuscinetti, utilizzati essenzialmente da centrali elettriche.
Abstract
The foundry industry is historically associated with bad manufacturing practices and poor conditions of working. Consequently, the implementation of right production practices is essential, especially for the SMEs of this industry, which have limited possibilities to invest. The research methodology used for this project development, provides, starting from a best practices research, an analysis of the production problems and a study investments, a systematic approach for the implementation of operators manufacturing procedures within a SME foundry. In addition, underlying continuously the importance of the involvement of people for the project success, the paper demonstrates how new procedures can minimise the jobs reworked, their related costs and the delivery lead time, with the consequent achievement of a better customer service. For the validation of the method proposed, the research, realised as Individual Project at Cranfield University, has been developed in collaboration with J H Richards, a small family-run English company that produces and repairs bearings mainly for power stations.
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A
CKNOWLEDGEMENTS
First of all, I would like to thank Prof Gino Dini, professor of my master at Università di Pisa, for the opportunity to study at Cranfield University and to have the double degree.
At the same time, I have really appreciated the help of Prof Mark Jolly, who gave me the opportunity to realise this thesis and helped me to develop it. Particular gratitude is for Roger Kings, who not only guided me for the realisation of the project during my permanence in J H Richards, but he has also transmitted me his knowledge and gave me useful suggestions for my future career.
I am very grateful, also, to Robert Bellingham, Metalling Shop Manager at JH Richards, and to all the employees of the company. The collaboration with all of them, in fact, allowed me to reach the different planned objectives and to understand how to work in a real manufacturing environment.
A special thanks is for my family that allowed me to study abroad and that have supported me during all my studies. In particular, I am thankful because they have been important referring points for all these years.
At the end, I want to thank all friends, who have never stopped to support me even during difficult moments. I am grateful to all of them because, despite scattered in different parts of the world, everyone has had a particular role during my growth and has taught me something.
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C
ONTENTS
Sommario ... 1 Abstract ... 1 ACKNOWLEDGEMENTS ... II CONTENTS ... III LIST OF TABLES ... VI LIST OF FIGURES ... 7 1.INTRODUCTION ... 8 1.1 Problem Definition ... 8 1.2 Aim ... 10 1.3 Objectives ... 10 1.4 Project Scope ... 10 1.5 Paper Structure ... 13 2.LITERATURE REVIEW ... 152.1 SMEs in the Foundry Industry ... 15
2.2 5-S Technique ... 16
2.3 Cultural Change ... 18
2.4 Kotter’s Model for Cultural Change ... 20
2.4.1 Step 1: Establish a sense of urgency ... 22
2.4.2 Step 2: Create a guiding coalition ... 22
2.4.3 Step 3: Develop a vision and strategy ... 23
2.4.4 Step 4: Communicate the change vision ... 24
2.4.5 Step 5: Empower broad-based action ... 25
2.4.6 Step 6: Generate short-term wins ... 25
2.4.7 Step 7: Consolidate gains and produce more change ... 26
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2.4.9 Limitations of Kotter’s eight-step model ... 28
2.4 Empowerment ... 30
2.5 Research Gap ... 32
3.RESEARCH METHODOLOGY ... 33
3.1 Research Methodology ... 33
3.1.1 Phase 1: Literature Review ... 35
3.1.2 Phase 2: Identification of the Issues and Process Analysis ... 35
3.1.3 Phase 3: New Equipment Purchasing ... 35
3.1.4 Phase 4: Data Collection ... 35
3.1.5 Phase 5: Procedures for the Fluxing Process ... 36
3.2 Industrial Case Study ... 36
4.IDENTIFICATION OF THE ISSUES AND PROCESS ANALYSIS ... 39
4.1 Previous Research ... 39
4.2 Process Analysis ... 43
4.3 Process Map (Foundry Area) ... Errore. Il segnalibro non è definito. 4.3.1 Fluxing Process ... 46 4.3.2 Shot Blasting ... 52 5. NEW EQUIPMENT PURCHASING ... 57 5.1 Workbench ... 57 5.2 Thermometer ... 64 5.2.1 Infrared Pyrometers ... 66 5.2.2 Contact Thermometers ... 70 5.2.3 Thermometer Purchase ... 72
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6.DEFINITION AND IMPLEMENTATION OF NEW PROCEDURES ... 76
6.1 Data Analysis ... 76
6.1.1 Data Gathering and Time of Cooling ... 77
6.2 Procedures Definition ... 81
6.3 Procedures Validation... 82
6.4 Procedures Implementation ... 83
7.DISCUSSION OF THE RESULTS ... 84
7.1 Results ... 84
7.2 Limits ... 85
8. CONCLUSION AND RECOMMENDATIONS ... 87
8.1 Conclusion ... 87
8.2 Recommendations ... 87
9.REFERENCES ... 89
APPENDIX ... 100
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L
IST OF
T
ABLES
TABLE 1: THE ENGLISH EQUIVALENT OF JAPANESE WORDS, THEIR MEANINGS AND TYPICAL.SOURCE:HO,1999, P.312 ... 16 TABLE 2: OPTIMAL PARAMETERS FOR FLUXING ... 40 TABLE 3: LISTS OF WORKBENCHES SUPPLIERS ... 60 TABLE 4: ADVANTAGES AND DISADVANTAGES FOR THE DIFFERENT KINDS OF SENSORS (WATLOW,1995,LAST ACCESSED 13TH JUNE 2014) ... 73
TABLE 5: ADVANTAGES AND DISADVANTAGES FOR THE DIFFERENT KINDS OF SENSORS (WATLOW,1995,LAST ACCESSED 13TH JUNE 2014)THERMOMETER SELECTION GUIDE (TEGAM,2014; LAST ACCESSED:12TH JUN 2014) ... 73 TABLE 6:TEMPERATURE DATA ... 75
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L
IST OF
F
IGURES
FIGURE 1: FOUNDRY ENVIRONMENT. SOURCE: HTTP://VESUVIUS.ANNUALREPORT2012.COM/OUR-PERFORMANCE/FOUNDRY
-OPERATING-REVIEW.LAST ACCESSED:14TH JUL 2014. ... 8
FIGURE 2: SCOPE AND OBJECTIVES ... 11
FIGURE 3:PAPER STRUCTURE ... 14
FIGURE 4: COMPONENTS OF TQM PHILOSOPHY AND THEIR INTERRELATIONSHIPS. SOURCE:KHAN,2003, P.375. ... 18
FIGURE 5:KOTTER’S EIGHT STEPS FOR THE CHANGE.SOURCE:WERISK,AVAILABLE AT HTTP://WWW.WERISK.IT/EN/CHANGE-MANAGEMENT/. LAST ACCESSED: 12TH AUG 2014 ... 22
FIGURE 6: STAGES OF EMPOWERMENT AND AUTONOMY ... 31
FIGURE 7: RESEARCH METHODOLOGY ... 34
FIGURE 8: EXAMPLES OF BEARINGS MANUFACTURED BY JHRICHARDS ... 37
FIGURE 9: FISH BONE DIAGRAM FOR THE TINNING PROBLEM ... 39
FIGURE 10: BRUSH FOR FLUXING PURPOSE THAT LIES ON A RUST TABLE ... 41
FIGURE 11: POWDER FLUX USED AFTER TINNING. THE ORIGINAL FLUX IS A WHITE POWDER ... 41
FIGURE 12: ROPTIN FLUX: THE ORIGINAL FLUX IS CLEAN AND CLEAR LIQUID ... 41
FIGURE 13: PROCESS MAP (FOUNDRY AREA) ... 44
FIGURE 14: EXAMPLES OF FLUX ... 47
FIGURE 15: SHOT BLASTING. SOURCE: NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH EDUCATION AND INFORMATION DIVISION.(2011) ... 52
FIGURE 16:INCIDENCE OF EMISSIVITY ON THE CALCULATION OF THE TEMPERATURE ((FLUKE CORPORATION,2011.LAST ACCESSED:12TH JUN 2014) ... 66
FIGURE 17:VARIOUS PROBE TYPES ... 70
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1.
I
NTRODUCTION
1.1 Problem Definition
From 1960, the UK foundry industry has faced a sharp decrease, because of lack of investments. This sector, indeed, requires not only new technologies and a research of new alloys, but also a development of manufacturing strategies, more investments and a total quality awareness, in order to obtain an effective manufacturing control (Cheema et al., 1991). Nowadays, indeed, foundries, in order to face the international competition, need to sell not only higher quality products, but also to produce them more efficiently.
At the same time, the industry has a problem related to the human resources because of the difficulty to attract skilled employees. Thereby, giving a better image of the foundry, usually associated with the idea of a low paid job in a poor conditions environment, is another reason for manufacturing practices implementation. Figure 1 shows an example of a foundry environment.
Figure 1: Foundry Environment. Source:
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Nevertheless, improvements implementation is not always seen positively by the employees of a company for several causes, i.e. the uncertainty about the future, which often determine the projects failure. This is the reason why the management must have a clear idea about the objectives that have to be reached and must be capable to spread them in the entire organisation (Vermeulen, 1997).
The problem becomes even larger when the company is a Small Medium Enterprise (SME), where the possibility to realise significant investments is reduced and there are not usually defined procedures: the operators usually learn to do certain operations with hand down methods. The first aspect implies the impossibility to purchase new technologies which could improve some kinds of processes. The other one causes a large variability of the production performances, which cannot ensure a constant and efficient execution of the activities.
Starting from those considerations, this paper concentrates on the SMEs, which have a turnover lower than £6.5 million, a balance sheet total of less than £3.26 million and less than 50 employees (UK's Companies Act 2006). In particular, it discusses a systematic approach to follow for the improvement of the processes within the SME foundry industry, where there are not usually defined procedures and which requires certain attentions, due to work conditions and the handled materials.
The methodology to follow and the obtainable results depend a lot on the kind of company, the culture of the organisation and the current situation of the factory. However, in order to have the validation from a real experience, it has been considered, for the development of this paper, an industrial case study, which has supported the methodology, providing a direct example of application.
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1.2 Aim
The aim of this paper is to provide to the SME foundry industry a systematic approach for the implementation of new operators manufacturing procedures and a process control, able to reduce the quantity of jobs reworked.
1.3 Objectives
The different objectives defined for the achievement of the results are:
Best practices research and analysis of the problems that affect the quality of the products;
Purchase of the right equipment necessary to improve the work environment, the execution and the control of the processes;
Definition of new operators manufacturing procedures to ensure a correct execution and control of the processes;
Implementation of the procedures previously defined.
1.4 Project Scope
In order to have a better idea about the different objectives, in relation to the scope of the project, Figure XXX, therefore, presents the different objectives within the project scope and the different colours represent the steps of the methodology used to achieve the planned results.
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Figure 2: Scope and Objectives
It is evident from the map that the focus of the project has been on the Fluxing process improvement. In particular, three aspects related to that have been considered: the purchase of new equipment, the implementation of new procedures to maintain the workplace tidy and clean and the control of the temperature of the bearing during the fluxing. The project comprehended, also, a control of the temperature during the activities before the fluxing process, which have an influence on that.
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The first stage of the project, after the problems analysis, was the acquisition of new equipment that was necessary for the achievement of better results in the application of the Flux. In particular, it regarded the purchase of a new heavy workbench, on which the process will be carried out, and a new thermometer, able to calculate the temperature of the bearing along different activities within the foundry area with a high level of accuracy. This first stage comprehended also the choice of the best layout of the foundry, starting from the analysis of the actual one and taking in consideration the operators’ needs and the new workbench.
The second step regarded the implementation of new procedures for the operators, which guarantee a continuous maintenance of a cleaned and tidy workplace and a correct execution of the process. In particular, they were realised in an easy and clear way, considering the impact on the operators’ behaviour, and with a continuous approval from the employees, in order to ensure that they will be followed in the future. Their contents have focused on the cleaning actions to undertake with a certain repetition, on the right handling of the tools and on the other materials that are used during the process: the procedures and the new way of working considered, for example, that these items have to be maintained cleaned and tidy and consequently that they have to be placed in the right location when not used.
In addition, the procedures have taken into account the measurement of the temperature during the process. The previous research, in fact, defined the best conditions for applying the flux on the bearings, among which there is the optimal temperature at which the product should be during the flux application. This stage of the project, consequently, has defined the best way to measure this parameter, strictly related to the thermometer bought, and in particular what has to be done to avoid that the temperature is lower than the fixed target. At the end, it has been considered necessary a study of the conditions of the bearing before the beginning of the fluxing. In particular, it was believed to be useful to understand the temperature of the bearings when it is heated up, how much time they take to become colder before the Shot Blast and which is the
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temperature after this. The availability of these data, in fact, would allow to understand if the bearing is heated up too much at the beginning, so if there is a waste of time and energy, how much heat is lost during the process and how much time, approximately, the operators can wait before starting the fluxing. They were also useful to understand the current variability of the process and to have an idea about the different temperatures in relation to the bearings dimensions.
1.5 Paper Structure
The structure of the report is shown in Figure 2. After presenting the results of an in depth research on different subjects strictly related to the project, the paper shows the methodology applied for its development, which aims to be a general guide for other small companies that operate in the foundry industry. After that, it covers the different stages of the methodology followed to reach the different objectives: a study of the current situation and its problems, the steps for the identification and the purchase of new equipment necessary for the development of the following stages, the implementation of some procedures that guarantee a correct execution and control of a particular process within the foundry area. At the end, this paper, after a discussion about the results and the limits of the project, propose some recommendations for the future.
In relation to confidentiality issues, financial figures have not been included in this paper.
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2.
L
ITERATURE
R
EVIEW
2.1 SMEs in the Foundry Industry
It is possible to find a lot of researches that concern the current situation of the foundry industry and its future (Smith, 1980). In particular, this industry has faced a decline after 1960s (Griffiths et al., 1989) and nowadays in order to be able to compete effectively in the national and international market, needs to work very efficiently (Cheema et al., 1991).
In order to sustain the competition, companies that operate in this industry, i.e. casting, need to invest in new technology and equipment, which can increase their manufacturing capability. In fact, they are essential to reach long-term benefits and a competitive advantage (Lee, 1991).
At the same time, managers, during the last years, have had the role to improve the image of the foundry industry: in particular, they have had to lead the implementation of new manufacturing practices and become more market-oriented. Managers are also facing the problem to recruit skilled employees, who are not usually attracted by the image of the foundry, which is seen as a bad environment where to work (Lee, 1991).
At the end, in order to maintain a strong position in the market, a lot of attention to the quality is required. A focus on this aspect, in fact, can determine the reduction of unnecessary reworks and defects that imply losses of money and time. For this reason, it is important that operators are involved and trained in that activity, because they can avoid that a wrong part proceeds to following operations and consequently they can help to reduce the numbers of jobs reworked (Lee, 1991).
In particular, a foundry is characterised by many causes of variation due to the nature of the processes realised (Johnson, 1989). Casting, for example, is a complicated process, which includes different variables and which requires a deep knowledge, because its quality depends on a big quantity of interrelated factors (Kar, 1996). For this reason, a lot of companies are trying to implement
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a Six Sigma approach to improve their performances, in order to minimise the rejection rate (Singh and Mishra, 2011). However, in order to achieve those objectives, it is necessary a preliminary study of what are the main sources of defects, fining a right prioritisation (Greenhill andPalmer, 1973).
In this context, a main role is covered by the Small Medium Enterprises, which can be very innovative, thanks to their flexible structure and the shorter distance between the operators and the managers (Rothwell, 1982). Nevertheless, they present some barriers that can determine a refusal of new initiatives: managers are sometimes reluctant to take the risk of changing, there is a lack of knowledge about the evaluation of the risk and there is a lack of skilled sources (Rothwell, 1990).
2.2 5-S Technique
The 5-S practice, which can be considered as the first step for a TQM programme (Ho and Fung, 1994; 1995), is a widely used Japanese technique implemented to establish and maintain quality environment in an organisation (Ho, 1999). The name refers to five Japanese words, explained in Table 1: Seiri, Seiton, Seiso, Seiketsu and Shitsuke (Osada, 1991). This method is related to the improvement of the physical environment and of the design of the processes: in fact, most of the everyday problem could be solved thanks to this practice. The 5-S has become the prerequisite to perform well because it allows to make a good impression on the customers, to implement effective quality processes and to obtain good products or services (Ho, 1999).
Table 1: The English equivalent of Japanese words, their meanings and typical. Source: Ho, 1999, p.
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In particular, 5S is a system that aims to minimise wastes and increase productivity and quality maintaining of a workplace: it helps to build a routine, essential to have a smooth and efficient flow of activities (Bayo-Moriones and al., 2010).
5-S can be seen in two different ways: it can be considered as a philosophy in Japan and as a technique or tool in USA and UK (Gapp et al., 2008). From the first point of view, in fact, it is thought as a strategy for the organisational development and improvement (Osada, 1991); on the other hand, it is described as an industrial formula to create a competitive advantage in comparison to other companies (Hirano, 1995).
Nevertheless, there are different opinions about the objective of 5-S: some authors consider it as “Housekeeping” (Ahmed and Hassan, 2003; Becker, 2001; Chin and Pun, 2002; Eckhardt, 2001), but more frequently it is associated to the lean philosophy and consequently it is viewed as a way to improve the processes and the conditions of the employees (James-Moore and Gibbons, 1997; Hines et al., 2004; Pavnaskar et al., 2003; Kumar et al., 2006; Gapp et al., 2008).
In detail, the different steps to follow for improving the work environment, according to this technique are (Bayo-Moriones et al., 2010):
Seiri: elimination of all those items unnecessary for the processes realised in the workplace;
Seiketsu: effective storage of all the necessary items, previously labelled, to make them easy to find and put away;
Seiso: cleanliness of the work area;
Seiton: standardisation of the different practices to ensure to avoid errors;
Shitsuke: application of these practices day by day.
The last S is probably the most difficult to implement and to achieve because that implies to change the behaviour and the way of working of proper. It is necessary to put a lot of effort into the change of culture in order to avoid a return to the previous situation (Bayo-Moriones et al., 2010).
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2.3 Cultural Change
Total Quality Management (TQM) is a philosophy that aims to reduce costs and improve customer satisfaction through a focus on customers, the employee empowerment, involvement and ownership of the processes, a continuous improvement strategy and the use of systematic approaches to management, as shown in Figure 3 (Khan, 2003).
In particular, the attitudes of organisation’s members are one of the main elements for the success of a company’s development and so, if employees are not involved and encouraged to change by managers, they are, at the same time, the principal cause of failure (Vermeulen, 1997). In fact, people are usually reluctant to change because they have fear to lose control, they are not sure about the responsibilities they will have in the future: they know that probably they will need to work more, the do not want to learn and apply new
Figure 4: Components of TQM philosophy and their interrelationships. Source:
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techniques and they always think about the bad consequences (Atkinson, 1990).
For those reasons, it is important that the management has an active role on transmitting a sense of ownership of the product to the operators, the desire to change and to improve the current situation, a feeling of co-dependence and the idea that every employee is responsible for their workplace (Ciampa, 1991). Consequently, the managers responsible of the change have to remember that a consensus from a group will determine a more successful change, that it is necessary to allow enough time to people to accept the change and that a train of employees is essential for the development of new skills (Deal and Kennedy, 1998).
Several researches have demonstrated that people expect that leaders have some attributes to be able to motivate them to undertake some actions. A leader must trust in the others and must have the ability to convince, inspire and encourage (Kouzes and Pozner, 1990). In addition, it is necessary that leaders have a clear vision of the future and communicate it through the definition of new objectives and the related strategies to reach them, which is necessary to maintain the people’s motivation (Dunphy and Stace, 1990; Hamel and Prahalad, 1994; Nadler, 1981; Vaill, 1993).
A key aspect to obtain the expected change is the communication about the future state, which can help to translate the vision in practical actions that have to be realised. A communication from the company’s members should be also stimulated in order to obtain feedbacks and help the managers to determine the future objectives to achieve (Stace and Dunphy, 1994). There are different forms of cultural communication that comprehend announcements, memos, slogans, ceremonies metaphors, etc. (Sathe, 1985).
Other effective practices to ensure a successful change are the empowerment of the operators and the assignment of rewards for good work (Block, 1987; Weisbord, 1989). They help, in fact, to generate high satisfaction and to realise a good quality work (Hackman et al., 1975).
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In order to obtain a successful change, it is required that a quantity of resources related to its size is allocated to its implementation. They could be for example additional human resources, new equipment, updated information systems, etc. and they should be used also as levers to support the change during its realisation (Nadler, 1981).
At the end, it is essential to highlight that the operators must be involved in the definition of the objectives that have to be reached and so that it is necessary a collaboration from both managers and employees to obtain high performance (Dunphy and Stace, 1990). In fact, the participation in the change helps to motivate people, to reduce the reluctance and to build ownership of the change (Nadler, 1981).
Among the different models proposed for the implementation of a change, one of the most relevant is the one proposed by Kotter (1995).
2.4 Kotter’s Model for Cultural Change
Businesses are constantly required to adapt to a changing environment in order to maintain their position in the market (Biedenbacha and Soumlderholma, 2008). Considering that, “research suggests that failed organizational change initiatives range from one-third to as high as 80% of attempted change efforts” (Fisher, 1994; Beer and Nohria, 2000; Higgs and Rowland, 2000; Hirschhorn, 2002; Knodel, 2004; Sirkin et al., 2005; Kotter, 2008; Meaney and Pung, 2008; Whelan-Berry and Somerville, 2010). Many studies, consequently, have been done in order to support managers in the field of change management.
In particular, one of the most relevant change management models has been the John P. Kotter’s model. According to this, there are eight steps to implement a change in an organisation (Kotter, 1996; Smith, 2005):
1. Establish a sense of urgency about the need to achieve change: people will not change if they cannot see the need to do so;
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2. Create a guiding coalition: assemble a group with power energy and influence in the organization to lead the change;
3. Develop a vision and strategy: create a vision of what the change is about, tell people why the change is needed and how it will be achieved; 4. Communicate the change vision: tell people, in every possible way and
at every opportunity, about the why, what and how of the changes; 5. Empower broad-based action: involve people in the change effort, get
people to think about the changes and how to achieve them rather than thinking about why they do not like the changes and how to stop them; 6. Generate short-term wins: seeing the changes happening and working
and recognizing the work being done by people towards achieving the change is critical;
7. Consolidate gains and produce more change: create momentum for change by building on successes in the change, invigorate people through the changes, develop people as change agents; and
8. Anchor new approaches in the corporate culture: this is critical to long-term success and institutionalizing the changes. If this is not done, it could happen that changes achieved through hard work and effort will slip away: people will revert to the old and comfortable ways of doing things.
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2.4.1 Step 1: Establish a sense of urgency
Successful change efforts must begin with individuals and groups evaluating a company’s “competitive situation, market position, technological trends and financial performance” (Kotter, 1995). Bold or risky actions normally associated with good leadership are generally required for creating a strong sense of urgency (Kotter, 1995, p. 43). In addition, leaders must find ways to communicate this information “broadly and dramatically” because the start of organizational changes require aggressive cooperation of many individuals (Kotter, 1995). This need for change must be understood, otherwise the people leading the change will not have enough “power and credibility to initiate the required change program” (Kotter, 1997). The use of external people to create a sense of urgency and challenge the status quo is also suggested, considering that they can help to reinforce the message (Kotter, 1996; Armenakis et al., 1993).
2.4.2 Step 2: Create a guiding coalition
It is not possible that one person is capable of leading the change alone. It is necessary to manage the change process in an organization and putting together the right “guiding coalition” of people to lead a change initiative to its
Figure 5: Kotter’s eight steps for the change. Source: Werisk, Available at
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success (Kotter, 1996). This guiding coalition should be made up of people with the following characteristics (Kotter, 1996):
Position power: enough key players on board so that those left out cannot block progress;
Expertise: all relevant points of view should be represented so that informed intelligent decisions can be made;
Credibility: the group should be seen and respected by those in the firm so that the group’s pronouncements will be taken seriously by other employees;
Leadership: the group should have enough proven leaders to be able to drive the change process.
This model requires a team of people with position power so that the change initiatives cannot be blocked, but this does not mean that there should be a monarchical attitude in the change leader (Kotter, 1996). In fact, if the management has an attitude of “command and control” and this behaviour does not change, transformation is destined to fail (Paper et al., 2001). Success of the change initiative depends on facilitative management and visible and continuous support from the top. A guiding coalition with good managers and poor leaders will not succeed (Kotter, 1996). Good managers keep the change management process under control while good leaders create the vision to drive the change (Kotter, 1996).
2.4.3 Step 3: Develop a vision and strategy
The first task of the guiding coalition from Kotter’s Step 2 is to formulate a “clear and sensible vision” for the transformation effort (Kotter, 1996). Without such a vision, the change objectives can easily dissolve into a list of confusing and incompatible projects that can take the organization in the wrong direction or nowhere at all (Kotter, 1996). An effective vision is essential in breaking the status quo and looking beyond the immediate goals of the organization (Kotter, 1996). A clearly defined vision is easier for employees to understand and to act on, even if the first steps required are painful (Kotter, 1996). Washington and Hacker (2005) found that managers who understand the change effort are
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more likely to be excited about the change and less likely to think that the change effort would fail. The change vision should therefore be desirable so that it appeals to the long-term interest of employees, customers, shareholders, and others who have a stake in the enterprise (Kotter, 1996).
2.4.4 Step 4: Communicate the change vision
Communication is a critical element of the organizational change process as it can reduce uncertainty (Bordia et al., 2004), decrease ambiguity and can even affect the type of positive or negative responses to organizational change (Nelissen and van Selm, 2008). Some studies found that the most significant correlations were between employee satisfaction and management communication. It was determined that employees who are satisfied with the management communication saw more personal opportunities and had a positive state of mind on the organizational change, lending support to Kotter’s fourth step (Nelissen and van Selm, 2008). Furthermore, these employees felt confident in the successful enrolment of the change (Nelissen and van Selm, 2008). Employees who felt the survival of the company depends on the organizational change showed positive responses regarding the high quality of management communication (Nelissen and van Selm, 2008). Other studies observed that communication is very important and so, for example, that weekly team meetings allowed employees to be trusting and open (Frahm and Brown, 2007).
The study results showed that frustrated employees typically felt this way due to a lack of involvement in the change process and due to a lack of information regarding the changes. However, there were sub-groups of employees who had a positive outlook about the changes (Nelissen and van Selm, 2008). Such employees viewed the necessary changes as an “opportunity for personal gain” and perceived change as “a welcome response to perceived organizational problems carried over from the past”. It was determined that these were also participants who were more involved in the change process compared to others. Therefore, in other researches, employees with a higher
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level of participation and greater dialogue responded more positively to change (Smith et al., 1995).
“Two-way communication is always more powerful than one-way communication” (Kotter, 1996) because it allows involvement, irons out ambiguities, and increases the chances of the communicators connecting adequately (Klein, 1996). In particular, face-to-face communication is “the best way that feedback can be used to correct deficiencies immediately in the communication process” (OConnor, 1990) because unaddressed inconsistencies undermine the credibility of all communication. Additionally, face-to-face communication in a group context allows for opportunities to be seen from different perspectives and interpretations, which can, in turn, be generated from explanations and clarifications related to variations of understanding (Weick, 1987).
2.4.5 Step 5: Empower broad-based action
Employees are emboldened to try new ideas and approaches, often just simply by the successful communication of the vision across the organization (Kotter, 1995). However, communication is never sufficient by itself and employees often need help in getting rid of obstacles to the change vision (Kotter, 1995). Typically, empowering employees involves addressing four major obstacles: structures, skills, systems, and supervisors (Kotter, 1996).
Kotter (1996) stresses the pivotal role of training in the empowerment process and he has broad empirical support for this assertion. Training is successful because it helps to build a sense of responsibility and empowerment in the employees (Denton, 1994). Some studies found that creating team ownership and a bottom-up or empowered employee base is important to help an organization transform successfully (Paper et al., 2001).
2.4.6 Step 6: Generate short-term wins
Seeing the changes happening and working and recognizing the work being done by people towards achieving the longer-term goals is critical in Kotter’s (1995) view. A large-scale change can be a long, formidable undertaking, so it
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is important to create short-term wins because a number of early victories, even if they are small, create self-confidence and the belief that bigger successes are possible and this builds up the momentum towards the longer-term goals (Pietersen, 2002). Rewarding opportunities and celebrating small wins also provide employees and management reassurance that their efforts are on the right track (Reichers et al., 1997; Marks, 2007). However, while to focus solely on short-term gains may increase the frequency of organizational change initiatives, finding the right balance between the short-term gains and the long-term effects of change on employee perception can become a complex issue for organizational leaders (Boga and Ensari, 2009).
Short-term wins demonstrate that the change effort is paying off (Kotter, 1996). Such wins help the guiding coalition test the vision against real conditions and make adjustments (Kotter, 1996, pp. 122-4). Short-term wins also help remove obstacles to change by reinforcing the change vision in the minds of employees (Drtina et al., 1996). Short-term wins also provide opportunities to celebrate and reward those working for change (Kotter, 1996, pp. 122-4). Throughout the transformation process, the leader should set high-performance expectations and reward behaviours that are directed toward fulfilment of the vision. It is also important that the leader models the behaviours that are required to institutionalize the change and sets the standards for the rest of the organization to emulate (Eisenbach et al., 1999). Step 6 appears to be significant in 2011 as it was in 1996.
2.4.7 Step 7: Consolidate gains and produce more change
Managers can be tempted to declare victory after the first signs of performance improvement are visible. However, as new processes can regress, it’s crucial for leaders to use these short-term gains in order to tackle other issues, such as systems and structures that are not in line with the recently implemented changes (Kotter, 1995). Management will require these first successes to plan for the further change process, and be able to partially justify the short-term costs incurred through change (Pfeifer et al., 2005). In fact, leaders will need
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to prove the “new way is working” (Kotter, 1995). First successes can also serve to “neutralize cynics and self-centered opponents” (Kotter, 1997). “Change-based momentum incorporates the prescriptions of transformational change agents, where momentum is described as a dynamic force whose presence or absence determines the ultimate success of a transformation” (Kotter, 1995; Linstead and Chan, 1994). Furthermore, change-based momentum can be initially created by “attaining a critical mass of accumulating support” (Jansen, 2004). Therefore, a positive relationship between employee commitment to change and change-based momentum must exist.
In addition, employees become part of the accumulating support the change is collecting as individuals choose to commit to the change process, thereby increasing their perception of the change-based momentum (Jansen, 2004). Committed employees are subsequently less resistant and less likely to want to maintain the status quo (Jansen, 2004). On the other hand, uncommitted employees or those who have lost their commitment over time are more likely to resist the change-based path (Hambrick et al., 1993). As a result, this can lead to a decrease in perception of change-based momentum. However, when “victory is declared too soon” (Kotter, 1996) or when management celebrate “the first clear performance improvement”, this can kill momentum. This also lost when, “the urgency level is not intense enough, the guiding coalition is not powerful enough, and the vision is not clear enough” (Kotter, 1996).
2.4.8 Step 8: Anchor new approaches in the corporate culture
New behaviours are subject to degradation if they are not rooted in social norms and shared values once the pressure for change is alleviated (Kotter, 1996). In particular, two factors are critical to the institutionalization of change in corporate culture:
1. Showing employees “how the new approaches, behaviours and attitudes have helped improve performance” (Kotter, 1996);
2. Ensuring that “the next generation of management personifies the new approach” (Kotter, 1996).
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However, an understanding of the forces and challenges that impede the growth and change processes must be present in order to deal with such challenges (Senge et al., 1999). A support structure for change agents is required in order for change to be sustained (Massey and Williams, 2006). This structure should offer mentoring, training, and shadowing opportunities. Different forms of communication and recognition of change initiatives should be used: newsletters, seminars, informal meetings, web sites, conferences/seminars, and visual display/storyboards of projects and progress (Massey and Williams, 2006). At the end, institutionalization processes include training to establish competence and commitment, meeting reward expectations, the further spread of new ideas and monitoring, and control processes (Buchanan et al., 2005). These steps and aforementioned studies allow the solidification of the change in the corporate culture of a company, lending support to Kotter’s final step.
2.4.9 Limitations of Kotter’s eight-step model
Kotter’s eight-step model was fully elaborated to address “fundamental changes in how the business is conducted in order to help cope with a new, more challenging market environment” (Kotter, 1995). This statement implicitly states a framework in which the model is applicable; therefore it is not expected to be applicable to all types of changes. Following are a few examples where the model might not be applicable without modifications.
The eight steps should be followed in sequence and an overlapping of the steps will compromise success, implying that steps are requisite of one another (Kotter, 1996). Therefore, not implementing the first step will make it difficult or impossible to implement the subsequent steps. Nevertheless, there are other perspectives that highlight that such a prescriptive approach does not correlate well with studies that suggest that organizations prefer to use approaches to change that stems from their culture and thus cannot easily be amended or replaced (Cummings and Huse, 1989; Schein, 1985; Burnes and James, 1995). “Indeed, this may well give a clue as to why so many change projects are said to fail owing to the apparent inability of managers to follow
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the prescriptions for successful change laid down in the literature (Schein, 1985; Juran, 1988; Kearney, 1989; Kotter, 1995; Zairi et al., 1994)” (Burnes, 1996). A plausible explanation is that, where such prescriptions run counter to the organization’s culture, they will be either ignored or be ineffective (Burnes, 1996).
Some transformations do not require to go through certain steps. A simple example is the replacement of major software used to process operation, or the change of equipment on a manufacturing line. In these cases the changes are often irreversible, and so Steps 7 and 8 might not be has relevant. Other examples could include changes with need for a great deal of secrecy, were Steps 1 and 4 will be significantly undermined.
Companies implementing changes face many difficulties and the application of the model should limit those obstacles, but the model is not detailed enough to provide help in all scenarios. For example, resistance to change and commitment to change are major aspects of change management and complementary components outside Kotter’s model, such predictors to determine commitment to change, might be needed to address these Stephen (Jaros, 2010).
Studying major change management projects is inherently difficult, due to their sheer complexity. Major obstacles to those studies included:
The difficulties of implementing all of the eight steps (Sidorko, 2008; Penrod and Harbor, 1998).
The need for a long follow-up of the change project, to cover all the steps. Changes usually require many years to take form, making the study time consuming. Validation of Steps 7 and 8 are therefore more complicated to evaluate (Penrod and Harbor, 1998; Betters-reed et al., 2008).
Difficulties encountered in evaluating the level of implementation of the steps, and the challenge of corroborating implementation level with
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implementation success level (Sidorko, 2008; Penrod and Harbor, 1998; Dianis et al., 1997).
2.5 Empowerment
As already shown, the involvement of the operators is fundamental to obtain a successful change. In particular, employee empowerment can be defined as the practice of involving people in the decision-making process (Rowlands, 1995), which can determine a change in the attitude to a more proactive one (Leach et al., 2001). Consequently, in order to obtain employees empowered, it is necessary that people receive more freedom and more power, in order to allow them taking initiatives, risks and decisions (Smith, 1997). The origin of this concept can be found in the idea of job enrichment, which refers to the increasing of control and decision making of a person, (Herzberg, Mausner et al., 1959; Herzberg, 1968).
Empowerment can be realised in different ways and it can determine different situations: employees can have the opportunity to buy shares of the company (Bartkus, 1997; Nesheim, 2011); managers supervise more people and tend to delegate decisions (Malone, 1997; Hyland et al., 1998); subordinates feel more motivated to perform well in order to respect superior’s expectations (Keller ad Dansereau, 1995); employees can have the opportunity to suggest and implement ideas, participating as partners to strategic decisions (Yukl and Becker, 2006; Garfield, 1993). Considering all these aspects, the role of management is to create a culture of participation, to stimulate the flexibility and the autonomy and an integration between the work and life of the employees (Honold, 1997).
In Figure 5, five different levels of empowerment in which a team with its manager operates can be identified (Pastor, 1996).
It is important to highlight that it is not important at which level, in terms of evolving, the team and the manager are. On the contrary, it is fundamental that team know at which stage it works for given situations, in order to avoid mismatch of stages. In fact, if the manager for example does not take into
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consideration team suggestions, that will determine conflicts, fear and anger and consequently, people will be hesitant and reluctant to give future recommendations (Pastor 1996).
Giving more responsibility to the operators can be very successful if correctly
implemented. It helps, indeed, to motivate people to reach higher performance, but at the same time it can improve efficiency, reduce costs, gaining time and money, as Diageo has demonstrated (The Manufacturer, 2010). Nevertheless, empowerment is not always successful and so there are aspects that have to be consider in order to avoid a failure. In particular, it is necessary to train the employees and to give them time to learn (Hyland et al., 1998; Bunning, 1992). It is also fundamental that the management trusts the operators, is patient and pay the employees for the success with some recognitions (Hyland, 1998).
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2.6 Research Gap
As demonstrated from the research carried on, many authors have shown a lot of interest in the foundry industry, its decline and its challenges within the national and international competition. At the same time, it is evident how much is important a knowledge about how to lead a change, in order to ensure the achievement of successful projects. With particular reference to SMEs, it is evident, in addition, the fundamental role covered by the operators, because of the flat hierarchical structure.
Despite all the studies related to the cultural change, the empowerment of the operators, the way to improve work conditions and the current situation of the foundry industry, there is still a lack of a systematic method to follow for the implementation of new procedures related to process improvements in a foundry of a SME. The standard approach proposed in the literature does not consider, in fact, the particular characteristics of that industry, which regard the traditional image of it, the reluctance of the management to embrace a risk and the high variability of the production processes, often combined with a lack of process control. The paper aims, therefore, to fill this lack.
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3.
R
ESEARCH
M
ETHODOLOGY
This chapter presents the methodology followed for the development of the project: it wants to be a general systematic approach, potentially usable by the small companies that operate in the foundry industry. In particular, in order to have a validation from the reality, it has been taken in consideration a real case study, which supports the different steps realised for the achievement of the objectives.
Considering the aim of the project, both quantitative and qualitative approaches were used for the research methodology. In fact, it was required not only the observation of the processes and a subjective valuation, but also a collection and analysis of the data, a detailed description of the characteristics of the equipment to be purchased and a quantification of the obtainable benefits.
3.1 Research Methodology
Figure 6 shows the five steps of the methodology developed, with the different
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3.1.1 Phase 1: Literature Review
The first phase of the project was the realisation of a literature review based on journal papers, books and previous researches. The objective was to understand the industry on which the project is concentrated and how to improve a workplace, through an analysis of the 5-S technique.
Considering the relevant impact of the project on the operators and their way of working, Cultural Change and Empowerment were other two topics on which the research focused. The implementation of new procedures constitutes, in fact, a big change, ant so it requires particular attention.
3.1.2 Phase 2: Identification of the Issues and Process
Analysis
This stage was necessary to analyse the process issues, key step for the development of the project. In particular, working on the industrial case study, different reports related to experiments, realised by the company during a previous project, were analysed. In contemporary, some visits to the shop floor were carried on, in order to understand the execution of the different activities within the foundry and to start to enter into contact with the operators.
3.1.3 Phase 3: New Equipment Purchasing
The preliminary step for the implementation of new manufacturing procedures was the identification of the new equipment necessary to apply the change. In particular, analysing the case study, it was considered necessary the acquisition of a new workbench, where to realise one of the processes considered critical, and of a thermometer, essential for the process control. In order to guarantee the purchase of the right items, it was underlying the importance of the definition of exact specifications and of the choice of the supplier.
3.1.4 Phase 4: Data Collection
During this stage of the project, it was considered essential the collection of quantitative data for a further analysis of the process. The case study, in
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particular, has involved the measure of the temperature during the processes that precede the Fluxing, the key activity analysed by the project. These temperatures, in fact, helped to understand the current variability of the process, confirming the necessity of a process control.
3.1.5 Phase 5: Procedures for the Fluxing Process
The last step of the project required that most of the time was spent on the shop floor in order to understand the actual way of working of the operators, to talk with them to identify the different possibilities of improvement and to propose new procedures, considering their suggestions and opinions. In particular, the procedures realised regarded the different steps that the operators have to follow in order to maintain a clean and tidy workplace and to avoid contaminations that can determine a bad quality of the product, with consequent necessity to rework it. They also involved a process control, related to the temperature, which has never been done before.
The structure followed for writing the procedures and for their validation aimed to be a general guide for every organisation which needs to modify or create a standard way of realising the processes. However, as shown by the case study, the scheme followed refers more explicitly to a small company where usually each operator works differently, using only their intuitions. In these situations, there is usually a lack of clear procedures, determining in this way an increase of the variability described by Johnson (1989).
3.2 Industrial Case Study
Since 1880, J H Richards has been recognised as the leader in the field of white metal bearing refurbishment and, thanks to all the experience gathered, they have an unrivalled reputation for quality and reliability. The company, starting from the customer drawings or using reverse engineering techniques, produces and repairs bearings for power generators, including turbines bearings, motor bearings, etc. (Figure 7), with diameters from 10 mm until 1700 mm and with bronze, steel or cast iron as a backing material.
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During a previous work realised in collaboration with Cranfield University, described in Chapter 4.1, J H Richards studied the different sources of problems that cause defects during the tinning process, within the foundry area of the plant in Birmingham. The aim was to identify the issues in order to eliminate them and reduce the quantity of jobs reworked.
In particular, the defects identified were due to oxides and other contaminations on the metal surface, which can be eliminated physically with shot blasting, a surface treatment process that uses high velocity steel abrasive, and chemically removed by fluxing, application of a chemical cleaning agent. In Chapter 4.3, the entire process is explained in detail in order to give a clear understanding of the different activities realised for the manufacturing and repairing of the bearings, within the foundry area.
In order to have an effective process, it was experimented that flux needs to be applied under certain conditions (i.e. at a certain temperature) and within a clean work area: these aspects were never taken in consideration before. The previous research has already implemented some improvements and suggested some paths to follow to complete the work. Consequently, starting from that work, it has been necessary a full understanding of the processes, the implementation of new procedures for the execution of some activities and
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a standardised control of determined parameters. Considering the strong tradition of the company, indeed, the different activities are realised without a sequence established of steps, but based on the knowledge and the experience of the operators. For this reason, the entire project has required a continuous collaboration with the operators and the management.
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4.
I
DENTIFICATION OF THE
I
SSUES AND
P
ROCESS
A
NALYSIS
4.1 Previous Research
A previous collaboration between Cranfield University and J H Richards showed some issues that needed to be solved in order to improve the efficiency and the quality of the processes within the foundry area. In particular, some of them were already handled during the previous project through the implementation of some practices. On the contrary, other solutions were only proposed and they still needed to be implemented.
The previous project started from the company’s awareness of problems related to the tinning process for cast iron, mild steel and bronze, which cause a loss of money due to necessary reworks. The key point of the quality issues of this process is the metal to metal bonding, which is not realised effectively if the metal surface is full of oxides and other contaminations.
Figure 12 shows the Fish Bone diagram realised during the previous research:
it presents the possible sources of problems that cause the tinning defect. The different issues identified were results of several experiments run in laboratory
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which aimed to analyse the surface of the metal in relation to different conditions.
In particular, the project focused on oxide and carbon removal. Consequently, in order to solve the problems and reduce the number of products reworked, it was realised an investigation of the Fluxing Process, which should remove all the contaminations and oxides from the surface, in order to understand what are the best parameters to use during this activity. In particular, it was identified the right temperature of the bearing while the flux is applied, how much time the operator has to wait because the flux works and the best kind of flux to use, in relation to the material of the bearing. The optimal parameters to do the fluxing process and to reach the best tinning are presented in Table 6.
Nevertheless, it was also observed that other important causes of bad tinning were the conditions of the work areas and the lack of right procedures to follow for the right execution of the process and to maintain a clean work environment. Figure 8, Figure 9 and Figure 10 show the conditions of the work areas and of the tools used during the processes of fluxing and tinning before the beginning of this project.
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It is evident that, in order to improve the fluxing process, main cause of tinning problems, the control of the temperature, the time of the different operations, the kind of flux applied and the cleanliness of the work areas are the main aspects that need to be monitored. For this reason, the previous study suggested some improvements to implement:
Figure 10: Brush for fluxing purpose that lies on a rust table
Figure 11: Powder flux used after tinning. The original flux is a white powder
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Maintenance of rust free surfaces in tinning area;
Cleanliness of the used tools without a mixing them and stock in the holding area after use;
Avoid contamination among the different kinds of flux and apply the right flux to the right material;
Maintenance of fresh and clean flux through the use of smaller buckets and being sure the flux is used as soon as possible;
Maintenance of the working environment clean and tidy;
Timed and recorded application of flux;
Temperature control along the process;
Development of new operation guides to keep the consistency of the operation;
Application of the flux at the proper temperature;
Creation of staff training about documentation, record keeping, housekeeping, and recycling, because the actual way of recycling the material causes contamination.
Some of these suggestions have been implemented during the previous project:
Different kinds of flux are applied to the different kinds of material;
The flux is put in small buckets every day in order to ensure that the flux is fresh for the different products realised during the day and consequently changed more frequently.
In conclusion, despite the presence of some oral instructions, there are not defined procedures for the execution of the process, which comprehend, in particular, the control of the temperature and the maintenance of clean work areas. Those aspects constitute, in fact, are the main focus of the actual project which is concentrated, in particular, on the fluxing process, a critical step to obtain an effective tinning.
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4.2 Process Analysis
During the analysis of the issues identified, it was spent also time on the shop floor, with the aim of validating them, in particular those related to the cleanliness of the work areas, and to start to have a more detailed understanding of the process. It was also useful to begin to create a relationship with the operators, fundamental step for the following stages of the project.
Figure 13 presents the different stages realised in the foundry area for both
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Bearings are withdrawn from the stock area and taken in the foundry, where
they are not worked entirely, because the operations in this area regard one half of the bearing each time. They will be bounded together successively. The first step of the process is different depending on which kind of job has to be processed. In particular, a new bearing will be only heated up, while a
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bearing that has to be repaired requires the elimination of the residual white metal. For this reason, in the second case, the bearing is heated up until the temperature at which the white metal merges, around 300 °C, to be then removed. This activity is called Run Out. The following activities regard both the new bearings and those that have to be repaired.
The process continues with the Shot Blast (or Sand Blast), where sand at high velocity is used to clean and abrade the surface, in order to eliminate the oxides. On the shop floor, there are two machines. The first one is bigger and uses cast iron as sand and is used for the bearings which have steel or cast iron as a backing material. The second machine, on the contrary, is smaller and uses aluminium oxide as sand: this is used for bearings with bronze backing because it was observed that, with the other process, they were damaged.
After this first cleaning, a specific kind of Flux, a chemical cleaning agent, is applied on the internal surface of the bearing to facilitate the bonding of the white metal, but also to ensure that the surface is completed cleaned before the tinning process. In particular, the flux is applied manually with a brush on the internal surface, while, on the external one, whitewash is applied in order to avoid that this part has a reaction during the tinning. There are different areas where the flux is applied: they are simple workbench or platforms, which are used to do other processes too. This phase is critical to obtain good products, because if it is not executed correctly and on a clean surface, it causes problems with the bonding of the white metal.
At this point, the bearing is put in the tin pot, in order to obtain the chemical reaction for the realisation of the layer that will be bonded with the white metal. There are two tinning pots: one is small, is used for the small products and it is close to the fluxing area for the small bearings; the other tin pot is big and used consequently for the big products. After the timed required for the reaction, the bearing is taken out and the tinning quality is visually examined. If there are not problems the bearing passes to the next phase, otherwise it is put another time in the tin pot, after been scrubbed with powder flux.
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The final activity realised in the foundry area is the casting (or metalling). This process can be realise in two ways. The first kind of casting is “Gravity Casting”, which is realised pouring the white metal manually in the cavity between the internal diameter of the bearing and a mandrel: during the process the metal has to solidify starting from the bottom and bubbles have to be avoided. For these reasons, water is used to cool down the temperature at the bottom, a flame is used to reheat the metal on the surface and stick is used to avoid the formation of the bubbles. The other process is called “Spin Casting” and is an automated process that uses centrifugal force to generate the casting: this is a method that gives good results but that can be used only for bearings that do not have particular shapes, due to the process itself.
At the end of all those stages, the bearing goes out from the foundry area and they are submitted to operations of finishing and quality control.
Despite this detailed description of the processes that are carried out in the foundry, there are particular kinds of bearings that require additional small activities or some different steps. They have not been described because not relevant for the quality of the project.
In conclusion, the shot blasting and fluxing process are the two activities that have the main objective of preparing the surface for the tin pot. Considering that the main quality issues are due the oxides and contaminations that should be removed by those two processes, an in depth research about them has been developed during the development of the project.
4.2.1 Fluxing Process
Flux, shown in Figure XXX, has a vital role in virtually all air brazing processes and to use the wrong flux or applying it in the wrong way can have negative consequences on joint quality. In fact, reliable solder connections can only be
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accomplished with truly cleaned surfaces. Solvents can be used to clean the surfaces prior to soldering but are insufficient due to the extremely rapid rate at which oxides form on the surface of heated metals.
Fluxes consist of natural or synthetic rosins and sometimes chemical additives called activators. It is the function of the flux to remove oxides and keep them removed during the soldering operation. This is accomplished by the flux action which is very corrosive at solder melt temperatures and accounts for flux's ability to rapidly remove metal oxides. It is the fluxing action of removing oxides and carrying them away, as well as preventing the reformation of new oxides that allows the solder to form the desired intermetallic bond.
When heated, fluxes dissolve surface oxides and protect the cleaned surfaces from re-oxidation, transfer heat from the heat source to the joint; and remove oxidation products, allowing filler metal to contact and wet the base materials. Brazing fluxes—pastes or powders—fuse at temperatures below those needed to melt filler metals. Because fluxes must be in close contact with the joint surfaces, they are liquid or gaseous at brazing temperatures. They remove only surface oxides and tarnish; other contaminants—oil, grease,
