Rework Time Research Articles

Factors Predicting Singers’ Work Efficiency and Singers’ Singing Peak

Abstract The research focusses on understanding the controls and predicting singers’ work efficiency, which is measured by rework times (RwT) in the recording studios. We conducted a comprehensive literature synthesis to identify a set of nine critical factors combining advancements in both acoustic field and recording practice. We measured each of these potential variables while 10 individual singers performed the same original song independently. The pieces of music sentences (n = 380) were analyzed by the multiple linear regression method. We found that: In the recording process, the RwT of a singer are predicted mainly by intensity, singing duration (SinD) and rhythm consistency. SinD mediates the connection between intensity and RwT. A singing peak exists in the performance.

Visual inspection of mechanical components using visual imaging and machine learning

Machine learning and automation have become an integral part of the manufacturing industries. Industrial processes can be automated with current machine learning tools and high-resolution cameras which helps us drive towards industry 4.0. The central idea for the machine learning and automation project is to make the visual inspection process automated with high-precision part defect detection. One of the prevailing problems in modern factories is the quality inspection process whereby faulty components and products are shipped to the customers. The Grad CAM algorithm helps to identify regions of error and data thus collected from this can be effectively used to take required corrective measures. This makes quality inspection simpler, quicker, and more accurate. Errors can also be highlighted in the result which can be used to take corrective action so that the defective part can be removed. This can also help increase the quality of the final product, reduce production costs, and increase production efficiency. The computer model is trained with the help of data collected of defective and non-defective parts. As a result, faulty components can be isolated or repaired for further processes, hence reducing the rework time and increasing the plant productivity.

P‐8.5: Research on LED Pad Design in Glass‐based Mini LED Backlight

In the past two years, the field of glass-based mini LED backlight has developed rapidly. In this article, experimental research on the design of the LED pad is conducted, including the Cu thickness, stack-up structure and pad size. The experimental results show that after the LED is solidified, the copper at the bonding pad is consumed and intermetallic compounds (IMC) are formed. The IMC has a granular morphology, dispersed in the solder layer. The main components of IMC are Cu6Sn5 and Ag3Sn. When the copper thickness on the pad increases from 0.6um to 3.6um in turn, the proportion of IMC in the solder layer increases significantly. The formation of IMC can improve the connection strength, but too much IMC will reduce the mechanical strength and the rework times. The fundamental method is to suppress the reaction rate of the Cu layer and the SnAgCu solder. The Electroless Nickel Immersion Gold (ENIG) process is a feasible method, because the Ni layer can effectively reduce the formation rate of IMC, and Au layer can effectively prevent the Cu of the LED pad from being oxidized. In addition, when the expansion of the BP pad relative to the LED bump increases, the die bonding yield is also significantly improved. These verification results could provide reference for future mini LED product design and production.

Back to basics: fundamental principles of system dynamics and queueing theory

Back to basics: fundamental principles of system dynamics and queueing theory

The lean manufacturing system applied to an auto parts industry in the heavy vehicles segment

This paper aims to demonstrate how the adoption of a continuous improvement program, based on lean manufacturing tools, can benefit the production of automotive filters for heavy vehicles, considering improved productivity and reduced operational waste, with a consequent increase in effectiveness and cost reduction. In this study we used the lean manufacturing tools, mainly kaizen and value stream mapping. During its development, the application of a kaizen project in a production line of automotive filters for heavy vehicles, aimed obtaining increased productivity and better distribution of physical space, through the reduction of rework time, reduction of downtime due to maintenance and reduction of setup time. The use of lean manufacturing tools, through the instruments presented in this study, guaranteed the viability of improvements in the productive sector. This work allowed the observation of a consistent improvement in production capacity, with productivity increase, through the improvement of the operational time and reduction of time of waste. The best distribution of physical space and the best arrangement of items used by the production process were also achieved through the consolidation of two production lines.

The lean manufacturing system applied to an auto parts industry in the heavy vehicles segment

This paper aims to demonstrate how the adoption of a continuous improvement program, based on lean manufacturing tools, can benefit the production of automotive filters for heavy vehicles, considering improved productivity and reduced operational waste, with a consequent increase in effectiveness and cost reduction. In this study we used the lean manufacturing tools, mainly kaizen and value stream mapping. During its development, the application of a kaizen project in a production line of automotive filters for heavy vehicles, aimed obtaining increased productivity and better distribution of physical space, through the reduction of rework time, reduction of downtime due to maintenance and reduction of setup time. The use of lean manufacturing tools, through the instruments presented in this study, guaranteed the viability of improvements in the productive sector. This work allowed the observation of a consistent improvement in production capacity, with productivity increase, through the improvement of the operational time and reduction of time of waste. The best distribution of physical space and the best arrangement of items used by the production process were also achieved through the consolidation of two production lines.

Scheduling interrelated activities in complex projects under high-order rework: A DSM-based approach

Complex projects, such as product development projects, usually involve myriads of interrelated activities. Identifying an appropriate sequence of these activities is a challenge to project managers because of the existence of rework iterations. Researchers have developed a series of methods to find a schedule that minimizes the first-order rework of interrelated activities using the design structure matrix (DSM). By contrast, this study presents a more accurate approach for determining a sequence that minimizes the high-order rework. First, a new objective function is proposed to describe the first-order and second-order rework time (FSRT) of complex projects. Second, a parallel branch-and-prune algorithm and two local search heuristics are proposed, which can be conveniently used to reduce the FSRT. Experimental results show that we can reduce more rework of complex projects through minimizing FSRT than using other objective functions. Finally, the efficiency of the proposed methods is validated using random experiments.

Research on the rework risk core tasks in prefabricated construction in China

PurposeThe purpose of this paper is to assess the process of prefabricated construction (PC) and analyze the impacts of rework risk to identify the core tasks for which the rework risk has severe impacts.Design/methodology/approachThe methods consist of a literature review, expert interviews, a questionnaire survey and a rework risk function. The expert interviews and questionnaire survey were administered to experts in the entire process of PC from the dimensions of rework frequency, rework cost and rework time. Descriptive and inferential statistics were employed to analyze the data. The rework risk function was based on the loss expectancy method.FindingsThere are 13 core tasks that have higher impacts than the average level. The core tasks in the design stage account for 100% of the tasks in the stage, those in the manufacturing stage account for 20% and those in the construction stage account for 23.1%. Compared with the other stages, the design stage is characterized by significantly more frequent rework, higher rework costs and longer rework time. The manufacturing stage is characterized by significantly higher rework costs than the construction stage. The manufacturing stage and construction stage are co-reliant, and both are impacted by the design stage.Practical implicationsThe findings provide stakeholders with a clear understanding of the core tasks of the PC process and represent a method for identifying core tasks. Stakeholders can learn from this to focus on the core tasks to reduce rework risk and manage the process with the priority of PC rework management based on the following order: design > manufacturing > construction. The approach is suitable for core task identification in other areas.Originality/valueThis research provides insight into rework risk management and provides a novel analysis method for rework risk and PC management from the perspective of the construction process. The findings are valuable for supporting stakeholders in making effective construction plans to reduce the impacts of rework risk in PC and provide a reference for future research on process optimization.

A DSM‐Based CCPM‐MPL Representation Method for Project Scheduling under Rework Scenarios

Rework risks caused by information flow interactions have become a major challenge in project scheduling. To deal with this challenge, we propose a model integrating the critical chain project management method, design structure matrix method, and max‐plus method. Our model uses a start‐to‐start relationship of activities instead of the traditional finish‐to‐start relationship, which also allows overlaps between activities. We improve the accuracy of the rework safety time in two ways: (1) the overall overlapping effect is taken into consideration when calculating the rework time of an activity arising from the information flow interaction of its multiple predecessors overlapped with it; (2) the rework time arising from activity overlaps, the first rework time, and the second rework time are calculated as components of the rework safety time in our model, while the last one is ignored in traditional methods. Furthermore, the accuracy of time buffers is improved based on the improved rework safety time. Finally, we design the max‐plus method to generate project schedules and appropriately sized time buffers. The empirical results show that the project schedule generated by the proposed method has a higher on‐time completion probability, as well as more appropriately sized project buffers.

Multi-item single-source production quantity model for imperfect items with rework failure, inspection errors, scraps, and backordering

This paper represents a multi-item single-source (MISS) production quantity model for random imperfect items with repair failure, inspection errors, sales return, scraps, and backordering. In this study, it is assumed that some manufactured/produced goods might not be without fault and the first phase of inspection over the quality of goods might make some inspection errors through the classifying of imperfect/defective and perfect items. Besides, this model contains one or more steps of separation procedure that is after the rework time and there is no screening error in this period (i.e., error-free). The purpose of this investigation is to obtain the optimum cycle length and the optimal backordered quantity for each item to minimalise the total expected value cost. Finally, the numerical example is illustrated to explain and solve the studied model using our investigated innovative methodology, which is additionally clarified and explained over a sensitivity analysis.

Accounting Lean Management Model Based on Big Data

In the environment of slowing down world economic development, the uncoordinated extensive production and industrial policies in China in the past caused the imbalance of economic supply in China. In this paper, through the use of literature analysis, comparative analysis and case analysis, taking l manufacturing enterprise as a case, through the analysis of enterprise production mode and cost management mode, through the construction of lean accounting cost management framework, the cost management of l enterprise is studied from four aspects. Through the analysis, it can be seen that the non productive resources of employees account for 36.37%, of which the rework time accounts for 61.05%, and the handling time accounts for 23.26%. Compared with the traditional cost management, lean accounting is more suitable for the management of lean enterprises. Finally, the lean management of the enterprise is predicted.

Wearable shear force-sensing for augmenting manual hose connections in an automotive assembly

In automotive assembly, hose interfaces for engine and cooling applications are critical safety connections as they carry fluids that are essential to keep the engine running and can be flammable. Incomplete hose connections might loosen in operation resulting in fluid leakage and potential field warranty claims. The current quality control in manual assembly for such connections is a push-pull-push procedure (push to lock, pull to check, push to reseat) that relies on manual verification by the operator, which is a subjective evaluation of the connection quality. This research aims to convert this subjective evaluation of successful hose connection into an objective measure through a wearable shear force sensor that measures the operator-induced shear force during the assembly operation. This system could not only reduce assembly defects but also help in reducing the assembly rework time.

Mesh-based tool path calculations for tubular joints

Manufacturing of large steel tube structures is faced with excessive welding, fit-up and rework times in tube joints, due to various types of deviation from nominal shape of the tubes. This article presents a procedure and geometry calculus for generating cutting and welding paths based on measured geometries. The procedure poses the two measured meshes as per construction specification and invokes a mesh intersection procedure to get the mesh intersection path; performs an optional smoothing; interpolates the smoothed path to a specified angular resolution; estimates the two surface normal vectors and the two surface tangents in the plane spanned by the normals at each interpolation point; calculates the cutting tool and welding tool approach directions for obtaining the specified welding groove geometry at each interpolation point; and finally stores all the data parameterized by the interpolation angle. Illustrations of results with both synthetic, representative meshes and meshes obtained from scanning of actual tubes at the shop-floor at a manufacturer are presented. The reference implementation for the developed software tool is based on Python and uses the mesh modeller from the 3D creation suite Blender as platform.

Research on DSM-based Product Development Coupling Activity Overlapped Execution Model

Aiming at the problem of overlapping execution of coupling activities in the product development process, using Markov Chain method to describe the iterative process of coupling activities based on the design structure matrix (DSM). Then introduced the information output, input time factor matrix and rework risk matrix to describe the complex information interaction between design activities, constructed a model of rework time caused by design activity coupling and iteration by quantifying the overlap of design activities, and then established the entire project time cost model for coupled activity sets. Finally, an application analysis was performed with examples. The research shows that this method can effectively reduce product development time and provide a certain theoretical basis for the rational planning and scientific guidance of the overlapping execution mode of coupled activities in the product development process.

Multi-item single-source (MISS) production quantity model for imperfect items with rework failure, inspection errors, scraps, and backordering

This paper represents a multi-item single-source (MISS) production quantity model for random imperfect items with repair failure, inspection errors, sales return, scraps, and backordering. In this study, it is assumed that some manufactured/produced goods might not be without fault and the first phase of inspection over the quality of goods might make some inspection errors through the classifying of imperfect/defective and perfect items. Besides, this model contains one or more steps of separation procedure that is after the rework time and there is no screening error in this period (i.e., error-free). The purpose of this investigation is to obtain the optimum cycle length and the optimal backordered quantity for each item to minimalise the total expected value cost. Finally, the numerical example is illustrated to explain and solve the studied model using our investigated innovative methodology, which is additionally clarified and explained over a sensitivity analysis.

Cu CMP process development and characterization of Cu dishing with 1.8 μm Cu pad and 3.6 μm pitch in Cu/SiO2 hybrid bonding

A Cu/SiO2 hybrid bonding process was developed on 1.8 μm Cu pad size and 3.6 μm pitch. A Cu dishing profile was achieved with additional fine copper removal and barrier removal chemical mechanical planarization steps (named P2 rework and P3 rework) due to the different removal rate (RR) of Cu to SiO2. With increasing P2 rework time, the Cu dishing could be increased, because the RR of Cu was larger than that of SiO2. With increasing P3 rework time, the Cu dishing was decreased, which was due to the RR of Cu being lower than that of SiO2. The interface of Cu–Cu bonding with different Cu dishing after 350 °C annealing was studied. By choosing a proper Cu dishing value which is less than the Cu expansion in the 350 °C annealing, the daisy chain resistance per link of 1.2–1.5 Ω and 95% yield of 1000 daisy chain were achieved.

블록 정합 재작업 시수 예측 시스템에 관한 연구

In order to evaluate the precision degree of the blocks on the dock, the shipyards recently started to use the point cloud approaches using the 3D scanners. However, they hesitate to use it due to the limited time, cost, and elaborative effects for the post-works. Although it is somewhat traditional instead, they have still used the electro-optical wave devices which have a characteristic of having less dense point set (usually 1 point per meter) around the contact section of two blocks. This paper tried to expand the usage of point sets. Our approach can estimate the rework time to weld between the Pre-Erected(PE) Block and Erected(ER) block as well as the precision of block construction. In detail, two algorithms were applied to increase the efficiency of estimation process. The first one is K-mean clustering algorithm which is used to separate only the related contact point set from others not related with welding sections. The second one is the Concave hull algorithm which also separates the inner point of the contact section used for the delayed outfitting and stiffeners section, and constructs the concave outline of contact section as the primary objects to estimate the rework time of welding. The main purpose of this paper is that the rework cost for welding is able to be obtained easily and precisely with the defective point set. The point set on the blocks’ outline are challenging to get the approximated mathematical curves, owing to the lots of orthogonal parts and lack of number of point. To solve this problems we compared the Radial based function-Multi-Layer(RBF-ML) and Akima interpolation method. Collecting the proposed methods, the paper suggested the noble point matching method for minimizing the rework time of block-welding on the dock, differently the previous approach which had paid the attention of only the degree of accuracy.

Solving no-wait two-stage flexible flow shop scheduling problem with unrelated parallel machines and rework time by the adjusted discrete Multi Objective Invasive Weed Optimization and fuzzy dominance approach

Purpose: Adjusted discrete Multi-Objective Invasive Weed Optimization (DMOIWO) algorithm, which uses fuzzy dominant approach for ordering, has been proposed to solve No-wait two-stage flexible flow shop scheduling problem.Design/methodology/approach: No-wait two-stage flexible flow shop scheduling problem by considering sequence-dependent setup times and probable rework in both stations, different ready times for all jobs and rework times for both stations as well as unrelated parallel machines with regards to the simultaneous minimization of maximum job completion time and average latency functions have been investigated in a multi-objective manner. In this study, the parameter setting has been carried out using Taguchi Method based on the quality indicator for beater performance of the algorithm.Findings: The results of this algorithm have been compared with those of conventional, multi-objective algorithms to show the better performance of the proposed algorithm. The results clearly indicated the greater performance of the proposed algorithm.Originality/value: This study provides an efficient method for solving multi objective no-wait two-stage flexible flow shop scheduling problem by considering sequence-dependent setup times, probable rework in both stations, different ready times for all jobs, rework times for both stations and unrelated parallel machines which are the real constraints.

Disposal versus rework – Inventory control in a production system with random yield

In a production environment where random yield plays a fairly significant role, a decision has to be made on how to handle products that do not satisfy given quality requirements. We consider a single-stage production system with a positive production time and random yield. To ensure that only high quality items are sold to the customer, a post-production quality control system has been put in place. We compare two different strategies for defective items: disposal or rework. Disposal is possible without any time delay whereas the rework process requires a positive rework time. While disposed-of items leave the production process, reworked products stay in the process and are assumed to be as good as products that are perfect when they are initially produced. The end products are stored in a warehouse to satisfy stochastic demand. We show how to determine the optimal base-stock level, which is very difficult because of unknown covariances between orders. Subsequently, an optimization model is proposed to support the planner’s decision on which strategy to choose when it comes to whether to dispose of or rework defective items. By means of a sensitivity analysis we show which parameters directly affect this decision and give managerial insights. The analysis indicates that significant cost reductions can be obtained by choosing the best strategy for defective products.

On intra-supply chain system with an improved distribution plan, multiple sales locations and quality assurance.

Transnational companies, operating in extremely competitive global markets, always seek to lower different operating costs, such as inventory holding costs in their intra- supply chain system. This paper incorporates a cost reducing product distribution policy into an intra-supply chain system with multiple sales locations and quality assurance studied by [Chiu et al., Expert Syst Appl, 40:2669–2676, (2013)]. Under the proposed cost reducing distribution policy, an added initial delivery of end items is distributed to multiple sales locations to meet their demand during the production unit’s uptime and rework time. After rework when the remaining production lot goes through quality assurance, n fixed quantity installments of finished items are then transported to sales locations at a fixed time interval. Mathematical modeling and optimization techniques are used to derive closed-form optimal operating policies for the proposed system. Furthermore, the study demonstrates significant savings in stock holding costs for both the production unit and sales locations. Alternative of outsourcing product delivery task to an external distributor is analyzed to assist managerial decision making in potential outsourcing issues in order to facilitate further reduction in operating costs.