Dispatching rule for non-identical parallel machines with sequence-dependent setups and quality restrictions

This paper proposes a dispatching rule that guarantees a predetermined minimum quality level for non-identical parallel machines with multiple product types. Manufacturers are focusing on improving the overall quality of their products, as the demand for top quality products is increasing. Such changes increase the possibility of neglecting another crucial factor in manufacturing schedules, namely due date. Traditionally, jobs are dispatched with the focus on meeting due dates. That is, jobs are assigned to machines without consideration of product quality. This approach opens the possibility of manufacturing poor quality products. Realizing the shortcomings of the existing dispatching rules, manufacturers are tempted to dispatch jobs with the objective of maximizing product quality. With such an attempt, jobs are likely to be assigned to high performance machines only. In turn, waiting times will increase and job delays are inevitable. This research proposes a dispatching rule that satisfies both criteria, reducing due date delays, while ensuring a predefined product quality level. A quality index is introduced to standardize various product qualities. The index is used to ensure a predetermined quality level, whilst minimizing product delays. Simulations compare various dispatch methods, evaluating them based on mean tardiness and product quality.     

Combining an alternative multi-delivery policy into economic production lot size problem with partial rework

This paper combines an alternative multi-delivery policy into an imperfect economic production quantity (EPQ) model with partial rework, with the purpose of reducing supplier’s stock holding cost. We extend the problem examined by Chiu et al. [Chiu, Y.-S. P, Chiu, S. W., Li, C.-Y., & Ting, C.-K. (2009). Incorporating multi-delivery policy and quality assurance into economic production lot size problem. Journal of Scientific and Industrial Research, 68(6), 505-512] by considering an n + 1 delivery policy in lieu of n multi-delivery plan for the specific EPQ model with partial rework. Under such a policy, an initial delivery of perfect (finished) items is distributed to customer for satisfying product demand during manufacturer’s regular production time and rework time. At the end of rework, fixed quantity n installments of the finished products are delivered to customer at a fixed interval of time. As a result, a closed-form optimal replenishment batch size solution to the problem is obtained. A numerical example with analysis and comparison is provided to show practical usage of the proposed model and demonstrate its significant savings in stock holding cost.     

Value creation dynamics in a project alliance

Project alliance requires all parties to work together in good faith, share project risks, and make unanimous decisions for the betterment of the project. A key feature of successful implementation of a project alliance is a focus on value creation and value for money. This paper proposes a qualitative system dynamics model to specify and explain dynamics of value creation processes in the context of project alliance. By synthesizing the existing literature and reports on project alliancing, this paper identifies four processes that have a strong influence on the value created in the project alliance context: work progression, rework, redesign and innovation, and rescheduling. In addition, we show how these value creation processes are interrelated and evolve over time. The effectiveness of these processes is influenced by the capability and motivation of the project alliance partners to discover works that do not fully utilize the available resources, and make quick decisions to capture these benefits.     

Modelling the dynamics of design error induced rework in construction

Rework that is experienced in construction projects is often caused by errors made during the design process. Factors that contribute to design errors are identified and used to design and develop a systems dynamics model, which is used to simulate a number of practical scenarios that can be used to reduce design errors and rework. The model presented in this paper can enable design and project managers to understand better the process of design documentation and how design errors occur in construction projects.     

Quantifying the causes and costs of rework in construction

Very few construction companies and consulting firms in Australia measure their costs of quality. Consequently, it is difficult for them to prove that systems for preventing quality failures are cost-effective. Although the direct costs of a quality system can be quantified with some accuracy (salaries, costs of documentation, audits, etc.), the corresponding benefits are far more difficult to assess. Indeed quality failures have become an endemic feature of the procurement process in construction and invariably lead to time and cost overruns in projects. Thus, in order to improve the performance of projects it is necessary to identify the causes and costs rework. The research presented in this paper quantifies the causes, magnitude and costs of rework experienced in two construction projects that were procured using different contractual arrangements. The causes and costs of rework projects are analysed and discussed. The findings reveal that the cost of rework for the case study projects was 3.15% and 2.40% of their project contract value. Changes initiated by the client and end-user together with errors and omissions in contract documentation were found to be the primary causes of rework. It is recommended that construction companies and consultant firms (particularly design consultants) implement quality management practices as well as place emphasis on coordinating project documentation during the design development process so that the amount of rework in projects can be reduced or even eliminated.     

Investigating the client-related rework in building projects: The case of Singapore

Rework has become one of the most common concerns in construction projects. This study aims to investigate the client-related rework (CRR) in Singapore-based building projects. To achieve the objectives, a literature review and questionnaire survey was conducted and data were collected from 381 projects performed by 51 companies. The results confirmed that the client contributed most to rework. 41 of the 51 companies (80.4%) experienced CRR, and 226 of the 381 projects (59.3%) experienced CRR, which increased project cost by 7.1% and caused 3.3 weeks' delay on the average. Additionally, “replacement of materials by the client” was the cause with the highest frequency of occurrence, while “change of plans or scope by the client” contributed most to CRR and exerted most impact on project cost, schedule and quality performance. This study expands the literature and provides an in-depth understanding of the CRR in Singapore for both practitioners and researchers.     

手工软钎焊工艺技术（续一）实用电子组装技术

手工软钎焊是PCB组装和返修工艺中基本的工艺技术之一。主要针对现场要求、焊接工具选择、工艺参数设定、元件组装焊接及返修拆焊等相关内容,对手工软钎焊工艺技术进行详细阐述,为手工焊接从业者提供重要参考依据。     

BGA技术与质量控制

BGA是现代组装技术的新概念,它的出现促进SMT(表面贴装技术)与SMD(表面贴装元器件)的发展和革新,并将成为高密度、高性能、多功能及高I/O数封装的最佳选择。本文简要介绍了BGA的概念、发展现状、应用情况以及一些生产中应用的检测方法等,并讨论了BGA的返修工艺。     

CSP元件的返修过程

ＣＳＰ元件在返修领域给当今的电子工业带来许多挑战。为了能够成功地返修ＣＳＰ，返修设备制造商必须认真地考虑大家共同遵守的具体准则。文章主要讨论如何满足和超越ＣＳＰ元件的特殊需要，使大家在返修ＣＳＰ中更顺利。