Optimal disposition decisions for a remanufacturing system considering time value of products

This paper studies disposition decisions of cores where the value of returns deteriorates over time. Mainly in disposition decisions, a remanufacturer is interested to determine how many units to remanufacture and to salvage. To address this research problem along with value deterioration of returns, a rough-cut mathematical model is developed by considering various parameters of interest such as selling price, salvage value and remanufacturing rate with the aim to maximize total profit. Due to uncertainty limitations, the model can provide decision-makers with relevant insights about disposition decisions. Simulation modeling techniques are used to validate the proposed model. Numerical examples are presented to demonstrate the applicability of the model and to show the negative relation between the deterioration rate and the total profit. However, the above-indicated parameters of selling price, salvage value and remanufacturing rate work the opposite way

Performance evaluation of the remanufacturing system prone to random failure and repair

Implementation of new environmental legislation and public awareness has increased the responsibility of manufacturers. Remanufacturing has been applied in many industries and sectors since its introduction. However, only 10% to 20% of the returned products pass through the remanufacturing process, and the remaining products are disposed in the landfills. Uncertainties like high failure rates of the servers, buffer capacities, and inappropriate preventive maintenance policies would be responsible for most of the delays in remanufacturing operations. In this paper, a simulation-based experimental methodology is used to determine the optimal preventive maintenance frequency and buffer allocation in a remanufacturing line. Moreover, an estimated relationship between preventive maintenance frequency and Mean Time Between Failure (MTBF), is presented to determine the best preventive maintenance frequency. The solution approach is applied to computer remanufacturing industry. Analysis of variance (ANOVA), and regression analysis are performed to denote the most influential factors to remanufacturing cycle time (performance measures). A case study is used to show the applicability of the modelling approach in assessing and improving the cycle time, and the profit of a remanufacturing line . Managerial insights are highlighted to support managers and decision-makers in their quest for more efficient and smooth operation of the remanufacturing system

Optimal Kanban Number: An Integrated Lean and Simulation Modelling Approach

Kanban is credited as a major means to controlling the inventory within a manufacturing system. Determining the optimum number of Kanban is of great interest for manufacturing industries. To fulfill this aim, an integrated modelling approach using discrete-event simulation technique and Kanban Lean tool is developed for a pull system ensuring an optimum Kanban number. This research has developed a base-case simulation model which was statistically validated using ANOVA. Initial Kanban number obtained from the mathematical model of Toyota motor company is used to obtain initial results. A Kanban integrated simulation model is developed that employed the idea of pull system that required the arrival of a customer for a product and Kanban pair to proceed through the production steps. The Kanban-Simulation integrated model is further used to test the effect of different Kanban numbers to obtain the best value of Kanban which is selected as 275. This approach has been applied on a case company involved in the manufacturing of agricultural and construction metal hand tools. The optimum Kanban number is selected by simulating the model about three performance indicators: customer waiting time, weekly throughput, and Work-in-progress. The analysis of the results obtained from the proposed integrated Kanban-simulation model showed a 76.7% reduction in the inventory level. The integrated Kanban-simulation model has also given a minimum customer waiting time of 0.84 Hrs. and a maximum throughput value of 737 Pcs of shovels. The integrated Kanban-simulation model is useful for manufacturing industries working to avoid overproduction waste and greatly reduce inventory costs

Performance evaluation of reverse logistics enterprise – an agent-based simulation approach

Reverse logistics (RL) has been applied in many industries and sectors since its conception. Unlike forward logistics, retracing consumer goods from the point of consumption to the point of inception is not a well-studied process. It involves many uncertainties such as time, quality and quantity of returns. The returned products can be remanufactured, have parts harvested, or be disposed safely. It is important to implement these activities in a cost-effective manner. The aim of this research is to measure the performance of the RL enterprise with the help of an agent-based simulation model. The major entities in the RL network are considered as Agents that can act independently. There are several different agents: collector agent, sorting-cum-reuse agent, remanufacturing agent, recycler agent, supplier agent and distributor agent. The individual performances of the agents are measured and recommendations are given to improve their performance, leading to the enhancement of the total performance of the RL enterprise. The approach is applied to a case study involving cell phone remanufacturing

Environmentally Conscious Machining of Inconel 718: Surface Roughness, Tool Wear and Material Removal Rate Assessment

Flood cooling is a typical strategy used in the machining of difficult-to-cut materials where high temperatures are produced.Several environmental and health concerns are associated with the cutting fluids employed during this technique. Vegetable oil-based fluids appear to be the best substitute to conventional mineral/synthetic oils due to their environmentally friendly, biode-gradable, renewable, and less toxic properties. Therefore, this paper attempts to establish an environmentally conscious, flood-cooling alternative through replacing conventional fluids with a synthetic vegetable ester-based (Mecagreen 450) biodegradableoil to investigate the machinability aspects of Inconel 718. In addition to the cooling environment, cutting speed (vs), feed pertooth (fz), and axial depth of cut (ap) have been used as control variables. ATaguchi L9array has been selected for the design ofexperiments (DOE). Parametric effects and microscopic analyses have been carried out to investigate the three response param-eters, i.e., surface roughness (Ra), tool wear, and material removal rate (MRR). Tool wear analysis is further supplemented withscanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS)

Three-Dimensional Container Loading: A Simulated Annealing Approach

High utilization of cargo volume is an essential factor in the success of modern enterprises in the market. Although mathematical models have been presented for container loading problems in the literature, there is still a lack of studies that consider practical constraints. In this paper, a Mixed Integer Linear Programming is developed for the problem of packing a subset of rectangular boxes inside a container such that the total value of the packed boxes is maximized while some realistic constraints, such as vertical stability, are considered. The packing is orthogonal, and the boxes can be freely rotated into any of the six orientations. Moreover, a sequence triple-based solution methodology is proposed, simulated annealing is used as modeling technique, and the situation where some boxes are preplaced in the container is investigated. These preplaced boxes represent potential obstacles. Numerical experiments are conducted for containers with and without obstacles. The results show that the simulated annealing approach is successful and can handle large number of packing instances

Influence of Corrosion Rate on the Double Butt Welding Shapes Design for Low Carbon Steel

The aim of this paper is to demonstrate the influence of butt welding shapes on the corrosion rate, microstructure and temperature of carbon steel type St37.The double butt welding was performed by V angles 15°,30° and 45°. The finite element analysis via ANSYS software is performed, this analysis includes a finite element model for the thermal welding simulation. The temperature distribution was obtained. From the results of the microscopic structure it is evident that the geometric shape has an important role in the welding process, when the geometric value of the welding region gets bigger, the faults get less due to increase of heat quantity in the welding region and the corrosion rate for the rain water is less than of sea water. The work presents the finite element model for numerical simulation of welding in carbon steel St37 double butt welding

Electric vehicle battery state changes and reverse logistics considerations

Electric Vehicles are becoming trendy and proved to have no harmful exhaust like traditional fuel-powered vehicles which makes them one of the best solutions to reduce greenhouse gas emissions. As the world shifts towards electric vehicle adoption, we will need efficient power sources to provide enough capacity for all these vehicles to function. Lithium-Ion batteries are the driving force behind this new trend. The goal of this research is to analyze the lifespan and long-term ratio composition of Lithium-Ion batteries in electric vehicles by developing two models, an Absorbing Markov Chain model, and a Markov Chain Steady-State Census model. A sensitivity analysis is also conducted to alleviate the scarcity of enough input data. This research work shows that the lifespan of batteries can be extended by 4.5 years, which will have a positive environmental impact and reap economic benefits. Moreover, the long-term composition of batteries in New, Remanufactured, Repurposed and Recycled states can be projected. The increasing demand for Electric Vehicles globally has created a necessity for more batteries to power them, and these batteries require materials to be made. By considering reverse logistics processes, it is possible to recycle batteries and recover the valuable materials. Not only does this support the environment but given the rising demand and finite raw material supply, there is an opportunity to capture the economic benefit of recycling. From this research, the recovered materials cobalt, lithium, and nickel are calculated, and this is especially important for the optimal planning of sustainable manufacturing