Multidirectional motion occurs in total knee replacements (TKR), is a major factor in ultra high molecular weight polyethylene (UHMWPE) wear and is a requirement for wear tester and simulators. There are three ways the femoral component can move relative to the tibial component; sliding, rolling and gliding and these are defined by the slide to roll ratio. Previous wear tester research has investigated the effects of multidirectional motion and slide to roll ratio, individually but not combined. The project aim was to design a machine that combined multidirectional motion with variable slide to roll ratio. A three station wear testing machine was designed and built featuring flexion extension, variable anterior posterior translation, variable internal external rotation and a 2KN load per station. The TKR was simplified to a cylinder on flat. Lubrication was 25% bovine serum and each station had its own recirculation system. A million cycle validation test was successfully carried out on non-irradiated UHMWPE samples using a slide to roll ratio of 1 : 0.5 and the mean wear rate was 14.7mg/10^6 cycles. Polished areas and scratches from 3rd body abrasion were observed. Magnification revealed a fine ripple pattern with a 1-2 micron periodicity. Ripples were randomly oriented, perpendicular to the primary direction of motion and a small number were running parallel to the primary direction of motion, indicative of rolling motion. The results from the validation study show that the knee joint wear tester is capable of producing wear rates and wear mechanisms similar to those observed in other wear testers and knee joint simulators and has met the aim of the project.

With the rapid growth and competitiveness in the South African apparel retail industry, retailers and marketers face numerous challenges to remain competitive. Contributing to the dynamic nature of this phenomenon is the impulsive nature and individual preferences of consumers when buying apparel, which necessitate retailers to be more responsive towards consumer needs and preferences in order to attract potential, and retain existing, customers. This can be done by formulating a retail strategy that will enrich consumers' total retail experience. When developing a total retail experience, all the elements that would encourage or inhibit the consumer to buy from the retailer should be considered, which among others include the store attributes applied within the store environment. This implies that apparel retailers, and especially those selling casual wear, should identify the importance attached to store attributes of their particular target market and how satisfied they are with the attributes offered. Since consumers use store attributes during store selection, it is essential for retailers and marketers to understand consumer behaviour, and more specifically the consumer decision-making process, since store attributes are used as evaluative criteria during this process. To satisfy consumer needs, retailers should meet consumer expectations in order to generate a positive attitude towards the store, which will increase the chances of repeat patronage. Consumer expectations form an essential part throughout the consumer decision-making process, which in the end will determine whether consumers experience post-purchase satisfaction or dissatisfaction. Since consumer expectations are formed by previous experiences, marketers should ensure that they offer the necessary store attributes consumers perceive as important when purchasing products, services or selecting a store. Evidently, this will influence both consumers' satisfaction towards a certain retail store, as well as future store selection. The primary objective of this study was to determine the importance of, and satisfaction with, store attributes to black Generation X consumers when choosing a store selling casual wear. An interviewer-administered questionnaire was used to survey 252 black respondents at a mall in Soweto. The questionnaire aimed to determine which store attributes are important to black Generation X consumers when selecting a store selling casual wear, and how satisfied they were with the store attributes offered by the store they most often buy casual wear from. Results identified 10 reliable Importance factors when determining which factors black Generation X consumers consider when selecting a store selling casual wear, namely service provided by salespeople; check-out points, dressing. rooms, store hours and proximity to store; display of casual wear and in-store advertising; store appearance, styles, sizes and quality of casual wear; physical facilities to enhance shopping convenience; offering cell phones and accessories; music played; price of casual wear; variety of brand names and credit card facilities; and the alteration of clothing and lay-buy services. It was also found that respondents were less satisfied with certain store attributes offered by the store they most often buy their casual wear from when compared to how important these factors were to them, including service provided by salespeople, check-out points, dressing rooms, store hours and proximity to the store. It is recommended that retailers who sell casual wear to black Generation X consumers should determine which attributes are considered as important to their target market and apply it in their retail and marketing strategies accordingly. It is also recommended that stores selling casual wear should conduct research to determine whether differences exist between their target markets' demographic profile with regard to the importance of store attributes as well as their satisfaction with those attributes offered by the store. Based on these results, marketers will be able to identify the attributes consumers are not satisfied with, which gives the opportunity for improving and amending strategies and gaining a competitive advantage. Future research can focus on the importance of store attributes to black Generation X consumers or other groups in other units of analysis, such as different retail formats and industries, as well as expanding the study to include more geographic areas. / Thesis (M.Com. (Marketing Management)--North-West University, Potchefstroom Campus, 2010.

Since the retail industry is marked by intense competition, retailers must examine the factors influencing the buying behaviour of their targeted consumers and ensure that they formulate a retail strategy that contributes to a pleasant consumer retail experience. Consumers' total retail experience is determined by numerous store attributes that interact, implying that apparel retailers (and stores selling casual wear in particular) should be concerned with store attributes that are important to their target market as well as their satisfaction with the current store attributes they offer. In view of the fact that consumers evaluate store attributes when making store selections, it is imperative that stores selling casual wear must be familiar with consumer behaviour, specifically the consumer decision-making process, as this process guides consumers to determine if, what, when, where, how, from who and how often to purchase products and services. Consumers enter into a retail experience with a set of expectations of what they would like to happen and what store attributes should be present. Consumer expectations influence the manner in which store attributes and other stimuli from the retail environment are interpreted. Evidently, an attractive store environment can be perceived as unsatisfactory if it fails to meet consumers' desired level of expectations. Thus, expectations influence consumers' satisfaction with the retail experience as well as store attributes offered by the store, which in turn affects consumers' overall satisfaction and store selection choices. The primary objective of this study was to determine the importance of, and satisfaction with, store attributes to black Generation Y consumers when selecting a store selling casual wear. An interviewer-administrated questionnaire was developed to determine which store attributes are important to black Generation Y consumers when selecting a store selling casual wear and how satisfied they were with the store attributes offered by the store they most often buy their casual wear from. Respondents between the ages of 16 and 24 were intercepted at a mall in Soweto by means of a non-probability convenience sample. In total, 261 respondents participated in this study. Results indicated that nine reliable Importance factors when determining which factors black Generation Y respondents consider when selecting a store selling casual wear could be identified, namely Service provided by salespeople; Check-out points, dressing rooms, store hours and proximity to store; Display of casual wear and in-store advertising; Store appearance, styles, sizes and quality of casual wear; Physical facilities to enhance shopping convenience; Offering of cell phones and accessories; Music played; Price of casual wear; and Alteration of clothing and lay-buy services. Further analysis indicated that respondents were less satisfied with Store appearance, styles, sizes and quality of casual wear than the importance of this factor to them. Results also indicated• that practically significant differences exist between various demographic variables of respondents and the importance of, and satisfaction with, store attributes offered by stores selling casual wear. It is recommended that stores selling casual wear who target black Generation Y consumers focus on the above-mentioned Importance factors and ensure that these stores attributes form part of their retail and marketing strategies. Stores selling casual wear should furthermore focus on improving customer satisfaction on those store attributes that are important to their customers. It is also recommended that stores selling casual wear conduct research to determine whether differences exist pertaining to their customers' demographic profile and their satisfaction levels with store attributes. Based on these results, customers can be grouped accordingly to identify strategies for improving customer satisfaction with store attributes. Recommendations for future research include comparison studies among different black cultures in South Africa to determine whether consumers differ regarding store attributes that are important to them in store selection as well as their satisfaction with a store delivering on those store attributes. Similar studies could be conducted among different population groups, age groups, income levels and geographic regions, as well as between consumers in developed and developing countries. It is also worthwhile to consider duplicating the study for other product categories to determine which attributes black generation Y consumers consider important when buying other products. / Thesis (M.Com. (Business Management)--North-West University, Potchefstroom Campus, 2010.

Wear particle-induced inflammation leading to periprosthetic osteolysis remains a major cause of hip implant failure. As polyethylene particles from conventional metal-on-polyethylene implants have been associated with these failures, an interest in lower wear metal-on-metal (MM) bearings has emerged. However, the biological effects of nanometer-size chromium oxide particles, predominant type of wear particles produced by MM implants, remain mostly unknown. Therefore, this study aimed to determine the cytotoxicity of nanometer-size Cr2O3 particles on macrophages in vitro, by analyzing their effects on cell mortality and cytokine release and comparing them with those of similarly-sized alumina (Al2O3) particles (known to be relatively bioinert). Results showed that at high concentrations, nanometer-size Cr2O3 particles can be cytotoxic to macrophages, inducing significant decreases in total cell numbers and increases in necrosis. Results also showed that, at high concentrations, the cytotoxicity of Cr2O3 particles was overall higher than that of Al2O3 particles, even though Cr2O3 and Al2O3 are both stable forms of ceramic materials. However, it appeared to be lower than that of previously reported conventional polyethylene and CoCrMo particles. Therefore, chromium oxide particles may not be the main culprit in initiating the inflammatory reaction in MM periprosthetic tissues.

Slurry coating technique, as one of the most popular deposition methods, is widely used to produce various material coatings. This method includes two processes: spraying, brushing or dipping of slurry, and sintering heat treatment of the coated specimen. Superalloys and stainless steels are the most common materials used as either coating materials or substrate materials because of their excellent corrosion, wear, high-temperature and mechanical properties. This research is aimed at investigating the influence of the sintering heat treatment in the slurry coating process developed at Kennametal Stellite Inc. on the microstructure, hardness and wear behavior of superalloys and stainless steels. Low-carbon Stellite 22, cobalt-based Tribaloy T-400C, martensitic AISI 420 and AISI 440C stainless steels are studied in this research. The microstructure, hardness and wear resistance of these alloys before and after the heat treatment are investigated, stressing the influence of the heat treatment on these material characteristics. The hardness and wear tested are conducted on these alloys at both room temperature and at elevated temperatures. The worn surfaces of each specimen are analyzed using a Scanning Electron Microscope (SEM) with backscatter electron imaging (BEI) and energy dispersive X ray (EDX) spectrum. It is demonstrated that the heat treatment alters the microstructures of these alloys differently; it increases the hardness but affects the wear resistance more complexly than hardness. At room temperature, the wear resistance of these alloys is governed by their microstructures. However, at high temperatures, oxidation, resulting in formation of oxide films on the specimen surface, influences the wear resistance significantly.

With the rapid growth and competitiveness in the South African apparel retail industry, retailers and marketers face numerous challenges to remain competitive. Contributing to the dynamic nature of this phenomenon is the impulsive nature and individual preferences of consumers when buying apparel, which necessitate retailers to be more responsive towards consumer needs and preferences in order to attract potential, and retain existing, customers. This can be done by formulating a retail strategy that will enrich consumers' total retail experience. When developing a total retail experience, all the elements that would encourage or inhibit the consumer to buy from the retailer should be considered, which among others include the store attributes applied within the store environment. This implies that apparel retailers, and especially those selling casual wear, should identify the importance attached to store attributes of their particular target market and how satisfied they are with the attributes offered. Since consumers use store attributes during store selection, it is essential for retailers and marketers to understand consumer behaviour, and more specifically the consumer decision-making process, since store attributes are used as evaluative criteria during this process. To satisfy consumer needs, retailers should meet consumer expectations in order to generate a positive attitude towards the store, which will increase the chances of repeat patronage. Consumer expectations form an essential part throughout the consumer decision-making process, which in the end will determine whether consumers experience post-purchase satisfaction or dissatisfaction. Since consumer expectations are formed by previous experiences, marketers should ensure that they offer the necessary store attributes consumers perceive as important when purchasing products, services or selecting a store. Evidently, this will influence both consumers' satisfaction towards a certain retail store, as well as future store selection. The primary objective of this study was to determine the importance of, and satisfaction with, store attributes to black Generation X consumers when choosing a store selling casual wear. An interviewer-administered questionnaire was used to survey 252 black respondents at a mall in Soweto. The questionnaire aimed to determine which store attributes are important to black Generation X consumers when selecting a store selling casual wear, and how satisfied they were with the store attributes offered by the store they most often buy casual wear from. Results identified 10 reliable Importance factors when determining which factors black Generation X consumers consider when selecting a store selling casual wear, namely service provided by salespeople; check-out points, dressing. rooms, store hours and proximity to store; display of casual wear and in-store advertising; store appearance, styles, sizes and quality of casual wear; physical facilities to enhance shopping convenience; offering cell phones and accessories; music played; price of casual wear; variety of brand names and credit card facilities; and the alteration of clothing and lay-buy services. It was also found that respondents were less satisfied with certain store attributes offered by the store they most often buy their casual wear from when compared to how important these factors were to them, including service provided by salespeople, check-out points, dressing rooms, store hours and proximity to the store. It is recommended that retailers who sell casual wear to black Generation X consumers should determine which attributes are considered as important to their target market and apply it in their retail and marketing strategies accordingly. It is also recommended that stores selling casual wear should conduct research to determine whether differences exist between their target markets' demographic profile with regard to the importance of store attributes as well as their satisfaction with those attributes offered by the store. Based on these results, marketers will be able to identify the attributes consumers are not satisfied with, which gives the opportunity for improving and amending strategies and gaining a competitive advantage. Future research can focus on the importance of store attributes to black Generation X consumers or other groups in other units of analysis, such as different retail formats and industries, as well as expanding the study to include more geographic areas. / Thesis (M.Com. (Marketing Management)--North-West University, Potchefstroom Campus, 2010.

Since the retail industry is marked by intense competition, retailers must examine the factors influencing the buying behaviour of their targeted consumers and ensure that they formulate a retail strategy that contributes to a pleasant consumer retail experience. Consumers' total retail experience is determined by numerous store attributes that interact, implying that apparel retailers (and stores selling casual wear in particular) should be concerned with store attributes that are important to their target market as well as their satisfaction with the current store attributes they offer. In view of the fact that consumers evaluate store attributes when making store selections, it is imperative that stores selling casual wear must be familiar with consumer behaviour, specifically the consumer decision-making process, as this process guides consumers to determine if, what, when, where, how, from who and how often to purchase products and services. Consumers enter into a retail experience with a set of expectations of what they would like to happen and what store attributes should be present. Consumer expectations influence the manner in which store attributes and other stimuli from the retail environment are interpreted. Evidently, an attractive store environment can be perceived as unsatisfactory if it fails to meet consumers' desired level of expectations. Thus, expectations influence consumers' satisfaction with the retail experience as well as store attributes offered by the store, which in turn affects consumers' overall satisfaction and store selection choices. The primary objective of this study was to determine the importance of, and satisfaction with, store attributes to black Generation Y consumers when selecting a store selling casual wear. An interviewer-administrated questionnaire was developed to determine which store attributes are important to black Generation Y consumers when selecting a store selling casual wear and how satisfied they were with the store attributes offered by the store they most often buy their casual wear from. Respondents between the ages of 16 and 24 were intercepted at a mall in Soweto by means of a non-probability convenience sample. In total, 261 respondents participated in this study. Results indicated that nine reliable Importance factors when determining which factors black Generation Y respondents consider when selecting a store selling casual wear could be identified, namely Service provided by salespeople; Check-out points, dressing rooms, store hours and proximity to store; Display of casual wear and in-store advertising; Store appearance, styles, sizes and quality of casual wear; Physical facilities to enhance shopping convenience; Offering of cell phones and accessories; Music played; Price of casual wear; and Alteration of clothing and lay-buy services. Further analysis indicated that respondents were less satisfied with Store appearance, styles, sizes and quality of casual wear than the importance of this factor to them. Results also indicated• that practically significant differences exist between various demographic variables of respondents and the importance of, and satisfaction with, store attributes offered by stores selling casual wear. It is recommended that stores selling casual wear who target black Generation Y consumers focus on the above-mentioned Importance factors and ensure that these stores attributes form part of their retail and marketing strategies. Stores selling casual wear should furthermore focus on improving customer satisfaction on those store attributes that are important to their customers. It is also recommended that stores selling casual wear conduct research to determine whether differences exist pertaining to their customers' demographic profile and their satisfaction levels with store attributes. Based on these results, customers can be grouped accordingly to identify strategies for improving customer satisfaction with store attributes. Recommendations for future research include comparison studies among different black cultures in South Africa to determine whether consumers differ regarding store attributes that are important to them in store selection as well as their satisfaction with a store delivering on those store attributes. Similar studies could be conducted among different population groups, age groups, income levels and geographic regions, as well as between consumers in developed and developing countries. It is also worthwhile to consider duplicating the study for other product categories to determine which attributes black generation Y consumers consider important when buying other products. / Thesis (M.Com. (Business Management)--North-West University, Potchefstroom Campus, 2010.

Abrasive wear occurs when a contact associated with stress between a metal surface and a herd particle (frequently of mineral origin) leads to friction between the two. In a very wide range of industrial applications, abrasive wear is the main reason for component and equipment repair or replacement. In most of these applications, especially those of earth moving, construction and mining equipment, digger teeth are used to improve equipment performance. Digger teeth can be produced in different shapes and sizes (mainly by casting) and a wide range of materials are used. This project is concerned with both a field trial of the wear of digger teeth fixed to the front of a bucket used in a gravel pit, and also a laboratory investigation of abrasive wear mechanisms. It was found that the wear of digger teeth increased with increasing working hours, but the wear rate eventually decreased. The dimensions and shape of the front of the tooth changed and gravel removal became more inefficient. Plastic deformation and phase transformation were observed in the worn surfaces of the teeth. In the laboratory study, many parameters were investigated utilising a pin-on disc technique. Wear rate increases linearly with load and decreases with sliding distance. The effect of attack angle on abrasive wear showed that wear volume increases with increasing attack angle up to a certain value (90°) and then decreases. Corrosion increases the initial wear rate, and the amount of material removed in the wet corrosive test was higher than the corresponding dry test. It was difficult to reproduce the same results from the field trial in the laboratory because of the difference in the conditions in the two cases. Optical and scanning electron microscopy were used to study the worn surfaces, abrasive papers and wear debris. Different abrasive wear mechanisms were observed throughout this investigation. A cutting mechanism associated with spiral debris was observed during short pin-on disc tests and with higher attack angles. A ploughing action associated with plate-like debris was observed during longer tests and at lower attack angles. Fragmentation was observed in brittle materials.

Tribological properties of a mica glass-ceramic designed for use in dental applications were assessed experimentally in accord with the ASTM pin on disk technique. The glass ceramic was produced through controlled crystallization of the glass in the system SiO2, Al2O3, CaO, MgO, K2O, and F. Crystallization was accomplished by subjecting the parent glass to a regulated heat treatment that resulted in the nucleation and growth of crystal phases formed in the glass. The tests were conducted by sliding a zirconia ball against the glass and glass ceramic disk. The friction coefficient and wear rate were determined as functions of the applied load, sliding speed and sliding time in ambient laboratory conditions and in acidic and basic solutions. The friction coefficient was monitored during the tests. The wear volumes determined from surface profile traces obtained on the wear tracks after completion of the tests were used for calculation of the wear rates. The wear rates increased with increasing applied load and sliding speed but decreased with increasing sliding distance. Results were correlated with the tribological properties of the parent glass, and tribological properties of selected glasses, glass-ceramics and ceramics reported in the literature.

The general trend in the car body manufacturing industry is towards low-series production and reduction of press lubricants and car weight. The limited use of lubricants, in combination with the introduction of high and ultrahigh-strength sheet materials, continuously increases the demands on the forming tools. The major cause for tool failure during the forming process is transfer and accumulation of sheet material on the tool surfaces, generally referred to as galling. The adhered material creates unstable frictional conditions and scratching of the tool/sheet interface. To provide the means of forming new generations of sheet materials, development of new tool materialswith improved galling resistance is required, which may include tailored microstructures introducing specific carbides and nitrides, coatings and improved surface finish. In the present work, the galling wear mechanisms in real forming operations have been studied and emulated at a laboratory scale by developing a test equipment. The wear mechanisms, identified in the real forming process, were distinguished into a sequence of events. At the initial stage, local adhesive wear of the sheets led to transfer of sheet material to the tool surfaces. Successive forming operations resulted in growth of the transfer layer with initiation of scratching of the sheets. Finally, scratching changed into severe adhesive wear, associated withgross macroscopic damage. The wear process was successfully repeated in the laboratory test equipment in sliding between several tool materials, ranging from cast iron and conventional ingot cast tool steels, to advanced powder metallurgy tool steel, sliding against medium and high-strength steel sheets. By use of the test equipment, selected tool materials were ranked regarding galling resistance. The controlling mechanism for galling in sheet metal forming is adhesion. The initial sheet material transfer was found to occur, preferably, to the metallic matrix of the tool steels. Hence, the carbides in the particular steels appeared less prone to adhesion as compared to the metallic matrix. Therefore, an improved galling resistance was observed for a tool steel comprising a high amount of small homogeneously distributed carbides offering a low-strength interface to the transferred sheet material.Further, atomic force microscopy showed that nanoscale adhesion was influenced by temperature, with increasing adhesion as temperature increases. A similar dependence was observed at the macroscale where increasing surface temperature led to initiation of severe adhesive wear. The results were in good agreement to the nano scale observations and temperature-induced high adhesion was suggested as a possible mechanism.