Improvement of location and orientation tolerances propagation control in cylindrical components assembly using stack-build assembly technique

2015 ◽  
Vol 35 (4) ◽  
pp. 358-366 ◽  
Author(s):  
Lei Wang ◽  
Chuanzhi Sun ◽  
Jiubin Tan ◽  
Bo Zhao ◽  
Gu Wan

Purpose – This paper aims to provide an assembly method to improve cylindrical components assembly quality. The proposed method not only could be applied to tolerance allocation, but also could guide the assembly of cylindrical components. Design/methodology/approach – The paper claims to provide a stack-build assembly method using a connective assembly model to take the location and orientation tolerances of a rotor stage into account. Through the separate analysis of the location and orientation tolerances propagation process in the assembly, the quality of the final assembly of the rotationally symmetric cylindrical components assembly could be improved by properly selecting component orientations to minimize the eccentric deviation in the assembly. Findings – The effectiveness of the proposed stack-build assembly technique in improving the tolerance propagation in the assembly of cylindrical components was verified through experiments run with a measuring machine. A real aero-engine rotor was assembly using the proposed method; compared to the direct-build assembly technique, which had the component orientations without consideration, the stack-build assembly technique could be used to reduce the eccentric deviation in cylindrical components assembly by nearly 50 per cent. Originality/value – Different with the old methods, the new method defined the tolerances in detail, such as perpendicularity and angle of the lowest point, and could guide the assembly by the features of surfaces on different components. Through measuring the special tolerances of surfaces on the components, the best assembly angle for each component could be obtained.

2017 ◽  
Vol 870 ◽  
pp. 459-464 ◽  
Author(s):  
Chuan Zhi Sun ◽  
Lei Wang ◽  
Jiu Bin Tan ◽  
Bo Zhao ◽  
Guo Liang Jin ◽  
...  

This paper aims to provide an assembly method to improve mechanical assembly quality. In order to improve the variation propagation control in rotationally symmetric cylindrical components assembly, the eccentric and tilt errors of a single rotor stage were taken into account using a connective assembly model and the eccentric deviation in a mechanical assembly was minimized by properly selecting component orientations. Compared to the minimum cumulative error, the maximum cumulative error was reduced by 71 percent, and the average cumulative error was reduced by 57 percent in the assembly of three components. This article provides an assembly method through variation propagation control in rotationally symmetric cylindrical components assembly. The method could be extended to rotationally symmetric cylindrical components assembly, for example in the assembly of aero-engine components.


2017 ◽  
Vol 30 (3) ◽  
pp. 301-311
Author(s):  
Steven T. Schwartz ◽  
Eric E. Spires ◽  
Richard A. Young

Purpose The purpose of this note is to expose accounting students and others to recent findings in management control, specifically to the relationship between the informativeness of a performance measure and its usefulness in performance evaluation. Design/methodology/approach Numerical examples illuminate key ideas and are easy to follow and replicate by students. Findings Seemingly in contradiction to the controllability principle, performance measures that are informative about actions taken by employees are not necessarily useful for performance evaluation. This occurs when the performance being measured is related to an intermediate task, such as prepping items prior to final assembly. If prepping is an important factor in the quality of not only the intermediate good but also the finished good, and the quality of the finished good can be reasonably measured, it may not be useful to measure the prepping performance. This result holds even if obtaining the intermediate measure is costless and the intermediate measure provides unique information on the effort given to the intermediate task. Originality/value Opportunities to measure employees’ intermediate outputs are ubiquitous; therefore, judicious decisions should be made regarding the use of limited monitoring resources. This note contains intuitive, easy-to-follow illustrations (based on recent findings) that will help students and others identify situations where such evaluations are more and less useful.


2016 ◽  
Vol 36 (3) ◽  
pp. 224-232 ◽  
Author(s):  
Hua Wang ◽  
Jun Liu

Purpose Tolerance simulation’s reliability depends on the concordance between the input probability distribution and the real variation. The prescribed clamp force introduced changes in parts’ variation, which should be reflected in the input probability distribution for the tolerance simulation. The paper aims to present a tolerance analysis process of the composite wingbox assembly considering the preloading-modified distribution and especially focuses on the spring-in deviation of the thin-walled C-section composite beam (TC2B). Design/methodology/approach Based on finite element analysis model of TC2B, the preloading-modified probability distribution function (PDF) of the spring-in deviation is obtained. Thickness variations of the TC2B are obtained from the data of the downscaled composite wingbox. These variations are input to the computer-aided tolerance tools, and the final assembly variations are obtained. The assembly of the downscaled wingbox illustrates the effect of preloading on the probability distribution of the spring-in deviation. Findings The results have shown that the final assembly variations estimated with the modified probability distribution is more reliable than the variation of the initial normal distribution. Originality/value The tolerance simulation work presented in the paper will enhance the understanding of the composite parts assembling with spring-in deviations, improve the chance to choose assembling processes that allow specifications to be met and help with tolerance allocation in composites assembly.


2014 ◽  
Vol 34 (3) ◽  
pp. 255-263 ◽  
Author(s):  
Xiang Gao ◽  
Hua Wang ◽  
Guanlong Chen

Purpose – Fitting evenness is one key characteristic for three-dimensional objects' optimal fit. The weighted Gaussian imaging method is developed for fitting evenness of auto body taillight fitting optimization. Design/methodology/approach – Fitting boundary contours are extracted from scanning data points. Optimal fitting target is represented with gap and flushness between taillight and auto body. By optimizing the fitting position of the projected boundary contours on the Gaussian sphere, the weighted Gaussian imaging method accomplishes optimal requirements of gap and flushness. A scanning system is established, and the fitting contour of the taillight assembly model is extracted to analyse the quality of the fitting process. Findings – The proposed method accomplishes the fitting optimization for taillight fitting with higher efficiency. Originality/value – The weighted Gaussian imaging method is used to optimize the taillight fitting. The proposed method optimized the fitting objects' 3-D space, while the traditional fitting methods are based on 2-D algorithm. Its time complexity is O(n3), while those of the traditional methods are O(n5). The results of this research will enhance the understanding of the 3-D optimal fitting and help in systematically improving the productivity and the fitting quality in automotive industry.


2019 ◽  
Vol 40 (6) ◽  
pp. 869-879
Author(s):  
Chuanzhi Sun ◽  
Danyang Chen ◽  
Chengtian Li ◽  
Yongmeng Liu ◽  
Zewei Liu ◽  
...  

Purpose This paper aims to provide a precision assembly method to improve the aircraft engine quality of initial unbalance with the purpose of founding the process for mass eccentricity propagation and demonstration of assembly process. The proposed method can be used for assembly guidance, tolerance allocation and so on, especially for the assembly with a large number of rotors and the assembly requirements of initial unbalance and coaxiality in high precision. Design/methodology/approach This paper proposes a constrained optimization-build method to minimize initial unbalance of aircraft engine assembly, which takes amount of unbalance and concentricity of each rotor into account. A constrained nonlinear programming model is extracted by choosing the initial unbalance as the objective function, and choosing the coaxiality and assembly orientations as the nonlinear constraints. The initial unbalance is reduced stage-by-stage by controlling the assembly angle of each rotor. Findings The validity and accuracy of the proposed method is verified by the multistage rotors assembly through experiments run with the measuring instruments. Compared with the direct-build method, the initial unbalance of final assembly using proposed method is reduced by 22.2% in four rotors assembly. Originality/value Different from the geometric eccentricity propagation control methods to reduce the initial unbalance indirectly, this paper establishes mass eccentric propagation model in multistage rotors assembly of aircraft engine for the first time. It provides a new idea to establish the relationship between the amount of unbalance of each rotor and the initial unbalance of multistage rotors.


2019 ◽  
Vol 26 (4) ◽  
pp. 340-351
Author(s):  
Alberto Carlo Cajavilca ◽  
Marta Tostes

Purpose The purpose of this paper is to examine the role and contribution of San Martin and Chazuta subnational governments in promoting development and internationalization of the cocoa and chocolate value chain from the stakeholders’ perceptions. This work was based on a qualitative approach in which information triangulation method, information processing with evaluation rubric and WebQDA software were used. The results showed that stakeholders of both value chains perceive that the subnational government’s actions taken to develop and internationalize these value chains are poorly valued and insufficient. Likewise, six internationalization barriers were identified in which two are perceived as the main limitations: low productivity levels and access to innovations and technology. These results contribute to enrich the decision-making process of political authorities and public officials from the San Martin subnational governments. Moreover, they provide information, according to the Peruvian national requirements, on the perceptions needed to rethink and improve the governmental services available, especially productive activities in the rainforest area (Presidencia del Consejo de Ministros, 2015; Wiener Fresco, 2010). This can improve or create new extension services to increase the quality of the Chazuta’s cocoa and chocolate products and to facilitate their entry into more demanding and profitable markets (Shapira, y otros, 2015). Design/methodology/approach This paper has been developed by using a qualitative approach with an exploratory and descriptive scope. The objective was to examine a study case of how subnational governments contribute in the promotion of development and internationalization of agro-industrial value chains as alternatives to illicit crops (Hernandez, Fernandez, & Baptista, 2010). The Chazuta case was selected because it is representative of the region in terms of coca eradication and is located between two regions of high biodiversity – Cordillera Escalera Regional Conservation Area and Cordillera Azul National Park. Findings One of the issues hindering the ability of the Chazuta cocoa and chocolate producers is based on their perception that the subnational governments’ efforts are focused on meeting already-established goals and little emphasis is placed on solving productive problems. On the other hand, at an articulation level, the most relevant efforts have been connecting the cocoa and chocolate customers to Chazuta producers through events. In spite of this, such events are not considered a permanent activity and the producers do not perceive that these mechanisms enable them to maintain these long-term trade relationships. This can be explained by the fact that Chazuta cocoa and chocolate organizations recognize that they still have incipient productive capacities to meet the foreign market’s demand. Furthermore, associations, cooperatives and SMEs are not able to maintain constant levels of production quality, except the family-based business. Knowledge and techniques provided by subnational governments and private organizations are not fully used or implemented by the associations’ members. This low level of knowledge application can be explained by cultural factors and also because the producers receive multiple and sometimes contradictory information from various providers of technology extension services. This leads to inadequate use or non-implementation of productivity improvements, thus generating a virtuous circle in which production and quality of the goods remain at low levels, which hinders their entry into demanding and profitable markets. Research limitations/implications This paper has been developed with a qualitative approach considering an exploratory and descriptive scope. Chazuta case was selected because it is representative of the region in terms of eradication achievements and it is located between two regions of high biodiversity. A rubric is an evaluation method of individuals or organizations performance, taking into consideration the evaluator’s pre-established criteria to determine if the objectives and goals are being met. Based on these criteria, evidence and performance information is collected. Following, performance is graded based on the researcher’s predetermined criteria and finally a merit-based judgment is made on the performance. Practical implications The results contribute to enrich decision making of political authorities and public officials from San Martin subnational governments. They provide information, according to Peruvian national requirements, on the perceptions needed to rethink and improve provided government services, especially in rainforest area productive activities. This adds up to improvement or creation of new extension services to increase the quality of Chazuta’s cocoa and chocolate products, and to facilitate their entry into more demanding and profitable markets. Social implications The situation of San Martín region and Chazuta district is contextualized and emphasis is given to socioeconomic conditions and the value of cocoa as an alternative crop to coca. From 1980 to early 2000, Peru lived a period of generalized violence due to narcoterrorism, which had large-scale outreach in southern highland and rainforest areas. To deal with this situation, subnational governments in collaboration with international cooperation decided to consolidate agro-industrial value chains in order to generate legal income for rural populations. For this purpose, alternative crop policies were implemented and San Martin region achieved the best results. Originality/value This fieldwork was carried out as part of the undergraduate thesis but after fieldwork, with the use of online software tool WebQDA, codes were created to systematize and quantify the collected information in the content manager. The codes were created taking into account assessment and evaluation variables. Each value represented a code referred to a performance level as perceived by Chazuta cocoa and chocolate value chains stakeholders.


2019 ◽  
Vol 19 (6) ◽  
pp. 1344-1361
Author(s):  
Isaiah Oino

Purpose The purpose of this paper is to examine the impact of transparency and disclosure on the financial performance of financial institutions. The emphasis is on assessing transparency and disclosure; auditing and compliance; risk management as indicators of corporate governance; and understanding how these parameters affect bank profitability, liquidity and the quality of loan portfolios. Design/methodology/approach A sample of 20 financial institutions was selected, with ten respondents from each, yielding a total sample size of 200. Principal component analysis (PCA), with inbuilt ability to check for composite reliability, was used to obtain composite indices for the corporate governance indicators as well as the indicators of financial performance, based on a set of questions framed for each institution. Findings The analysis demonstrates that greater disclosure and transparency, improved auditing and compliance and better risk management positively affect the financial performance of financial institutions. In terms of significance, the results show that as the level of disclosure and transparency in managerial affairs increases, the performance of financial institutions – as measured in terms of the quality of loan portfolios, liquidity and profitability – increases by 0.3046, with the effect being statistically significant at the 1 per cent level. Furthermore, as the level of auditing and the degree of compliance with banking regulations increases, the financial performance of banks improves by 0.3309. Research limitations/implications This paper did not consider time series because corporate governance does not change periodically. Practical implications This paper demonstrates the importance of disclosure and transparency in managerial affairs because the performance of financial institutions, as measured in terms of loan portfolios, liquidity and profitability, increases by 0.4 when transparency and disclosure improve, with this effect being statistically significant at the 1 per cent level. Originality/value The use of primary data in assessing the impact of corporate governance on financial performance, instead of secondary data, is the primary novelty of this study. Moreover, PCA is used to assess the weight of the various parameters.


2019 ◽  
Vol 14 (4) ◽  
pp. 251-263
Author(s):  
Daniel J. Carabellese ◽  
Michael J. Proeve ◽  
Rachel M. Roberts

Purpose The purpose of this paper is to explore the relationship of two distinct variants of dispositional shame (internal and external shame) with collaborative, purpose-driven aspects of the patient–provider relationship (working alliance) and patient satisfaction. The aim of this research was to conduct a preliminary investigation into the relevance of dispositional shame in a general healthcare population. Design/methodology/approach In total, 127 community members (mean age 25.9 years) who reported that they had regularly seen a GP over the past year were recruited at an Australian university. Participants were asked to reflect on their relationship with their GP, and completed instruments assessing various domains of shame, as well as working alliance and patient satisfaction. Findings Non-parametric correlations were examined to determine the direction and strength of relationships, as well as conducting mediation analyses where applicable. Small, negative correlations were evident between external shame and working alliance. Both external and internal shame measures were also negatively correlated with patient satisfaction. Finally, the relationship of external shame to patient satisfaction was partially mediated by working alliance. Practical implications Both the reported quality of patient–provider working alliance, and level of patient satisfaction are related to levels of dispositional shame in patients, and working alliance may act as a mediator for this relationship. Originality/value The findings from this preliminary study suggest that internal and external shame are important factors to consider in the provision of medical care to maximise the quality of patient experience and working alliance.


Author(s):  
Aaron Asibi Abuosi ◽  
Mahama Braimah

Purpose The purpose of this study was to examine patient satisfaction with the quality of care in Ghana’s health-care facilities using a disaggregated approach. Design/methodology/approach The study was a cross-sectional national survey. A sample of 4,079 males and females in the age group of 15-49 years were interviewed. Descriptive statistics, principal component analysis and t-tests were used in statistical analysis. Findings About 70 per cent of patients were satisfied with the quality of care provided in health-care facilities in Ghana, whereas about 30 per cent of patients were fairly satisfied. Females and insured patients were more likely to be satisfied with the quality of care, compared with males and uninsured patients. Research limitations/implications Because data were obtained from a national survey, the questionnaire did not include the type of facility patients attended to find out whether satisfaction with the quality of care varied by the type of health facility. Future studies may, therefore, include this. Practical implications The study contributes to the literature on patient satisfaction with the quality of care. It highlights that long waiting time remains an intractable problem at various service delivery units of health facilities and constitutes a major source of patient dissatisfaction with the quality of care. Innovative measures must, therefore, be adopted to address the problem. Originality/value There is a paucity of research that uses a disaggregated approach to examine patient satisfaction with the quality of care at various service delivery units of health facilities. This study is a modest contribution to this research gap.


2020 ◽  
Vol 13 (2) ◽  
pp. 73-87
Author(s):  
Linda Nesse ◽  
Marianne Thorsen Gonzalez ◽  
Geir Aamodt ◽  
Ruth Kjærsti Raanaas

Purpose Recovery for residents who experience co-occurring problems and live in supported housing takes place in everyday contexts. This study aims to explore residents’ self-reported recovery and quality of life and examine the relationships between these factors and issues in supported housing. Design/methodology/approach A cross-sectional study was conducted at 21 supported housing sites in six cities across Norway. A total of 104 residents (76 men and 28 women) responded to measures of recovery (Recovery Assessment Scale – Revised), life satisfaction (Manchester Short Assessment of Quality of Life), affect (single items), staff support (Brief INSPIRE) and sense of home (single items). Findings Linear regression analyses indicated associations between recovery and staff support (B = 0.01, 95% CI = 0.01-0.02, ß = 0.39), housing satisfaction (B = 0.15, 95% CI = 0.07-0.22, ß = 0.38), sense of home (B = 0.23, 95% CI = 0.14-0.32, ß = 0.49) and satisfaction with personal economy (B = 0.11, 95% CI = 0.05-0.17, ß = 0.33). Similarly, associations were found between life satisfaction and staff support (B = 0.03, 95% CI = 0.02-0.04, ß = 0.46), housing satisfaction (B = 0.63, 95% CI = 0.46-0.80, ß = 0.60), sense of home (B = 0.65, 95% CI = 0.42-0.87, ß = 0.51) and satisfaction with personal economy (B = 0.34, 95% CI = 0.19-0.50, ß = 0.39). Originality/value The findings imply that core issues in supported housing, namely, staff support, housing satisfaction, sense of home and satisfaction with personal economy, are associated with recovery and quality of life.


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