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- Production planning and inventory control in hybrid systems with remanufacturing
- Production Planning and Inventory Control in Pharmaceutical Manufacturing Process – PDF download
- MRP, JIT, OPT, FMS?
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Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Salomon Published Engineering, Mathematics. Customer demands must either be fulfilled from the production of new products or by the remanufacturing of used products.
Production planning and inventory control in hybrid systems with remanufacturing
IntroductionCare for the environment, environmental legislation, corporate image, and economical arguments motivate many companies these days to take responsibility for their products alter customer use see Thierry et al.
A popular way of dealing with this responsibility is to set up a program for the collection and further processing of used products 'returnables'. Possible options to further process returnables include remanufacturing, repair, recycling and disposal see [ 9] for further definitions of these options. The production and inventory system that we consider in this paper is a simplified version of a system that has been implemented successfully at a large Dutch manufacturer of photocopiers.
Used copiers are collected at the customer site and transported to a disassembly plant for disassembly into modules. Modules that satisfy certain specific quality requirements are remanufactured in a remanufacturing plant.
After remanufacturing modules are considered as 'new', and can in principle be assembled with newly manufactured modules to obtain a copier that is sold in the market for new products. Modules that do not satisfy the quality standards for remanufacturing are either used as spare-parts for the second-hand market or disposed of.
All rights reserved. PII S 17 97 than in traditional systems without remanufacturing. It has been experienced that these difficulties are mainly due to the many interactions that exist between the manufacturing, remanufacturing and disposal operations. Interactions between manufacturing and remanufacturing processes occur for instance when the output of the remanufacturing process is too low to satisfy all the demands for new modules adequately. In this case manufacturing orders must be placed regularly to avoid shortages.
To plan and control manufacturing, remanufacturing, and disposal operations simultaneously, the copier remanufacturer implemented a PUSH strategy. By this strategy returned modules are 'pushed' through the remanufacturing process as soon as a sufficient amount of modules becomes available from the disassembly plant.
If the joint inventory of new and remanufactured modules appears to be too low to satisfy the future expected demands adequately, a manufacturing order is placed to produce new modules.
In principle, disposal of a disassembled module occurs only when the quality of the module is insufficient for remanufacturing. The copier manufacturer had the impression that the efficiency of their system could be improved by the introduction of a control strategy which offers a higher level of coordination between the manufacturing, remanufacturing and disposal operations.
For this purpose, the change to a PULL strategy had been investigated. Under this strategy disassembled modules are 'pulled' through the remanufacturing process only when they are actually needed to satisfy the demand tot new modules.
If the output of the remanufacturing process appears to be too low to cover the future expected demands, a manufacturing order is placed.
Interactions between remanufacturing and disposal processes occur when the number of returned modules is higher than the demand for new modules. In this case some of the returned modules must be disposed of instead of being remanufactured to avoid too high, and therefore too expensive, stocking positions.
Therefore, another way that had been considered to improve the system efficiency is to not only dispose of returned products when their quality is too low for remanufacturing, but also when the system inventories become too high.
This paper is on production planning and inventory control tor systems in which careful coordination between manufacturing, remanufacturing and disposal operations is essential for achieving maximum system efficiency. In the production planning and inventory control literature numerous periodic review and continuous review strategies have been proposed that apply to similar systems as the one defined above.
For an extensive overview we refer to Van der Laan et al. In the brief overview below we restrict ourselves to the class of continuous review strategies, since the strategies that we consider in this paper also belong to this class. Although the strategy in [ 1 ] is optimal i.
The model that Muckstadt and Isaac [ 7 ] developed differs from Heyman's in the sense that they allow for non-zero manufacturing lead times, stochastic remanufacturing lead times, and finite remanufacturing capacity. Disposal operations are not considered and the procedure to find the optimal decision parameters is approximative. Van der Laan et al.
Limitations of  are however that the demands and returns are modelled by uncorrelated Poisson processes, and that holding costs of remanufacturables are zero. Furthermore, the procedure to calculate the total expected costs is approximative rather than exact.
In a followup paper Van der Laan et al. To control this system,  suggests two PUSH-strategies and presents an exact procedure to calculate the total expected costs. Both papers however do not consider disposal operations. Recently, an optimal EOQ-like policy for a deterministic system with manufacturing, repair, and disposal operations and zero lead times has been proposed by Richter [ 8 ].
The contributions of this paper are as follows. The cost structure consists of fixed and variable manufacturing and remanufacturing costs, possibly different holding costs for remanufacturables and serviceables, backordering costs, and variable disposal costs.
The procedures to calculate the total expected costs Section 3 are exact. In Section 4 we provide numerical examples i to show when and why systems with planned disposals i.
Finally, Section 5 presents our conclusions. System characteristicsThe system that will be considered in the sequel of this paper is shown in Fig.
It is basically a simplification of the system that has been implemented at the copier manufacturer. The first main simplification consists herein that our system applies to a single module remanufacturable product, rather than to a multicomponent product like a photocopier.
Consequently, we do not consider disassembly operations to disas-semble returned products into modules, and we have only two stocking points: one for remanufacturable products and one for serviceable products, i. The second main simplification consists herein that we assume that all returned products satisfy the quality requirements for remanufacturing. Consequently, only planned disposals need to occur.
The other system characteristics are as follows: 1. The total system costs per unit of time under strategy. This function reads as 2. The inter-occurrence times between two successive demands for new products and two successive returns of used products are Coxian-2 distributed see Appendix A. The correlation between demands and returns is modelled by the coefficient p, which is the probability that a product return instantaneously generates a product demand.
Demands that cannot be fulfilled immediately are backordered. The manufacturing lead time Lm and the remanufacturing lead time Lr are constant. Manufacturing starts whenever the inventory position which is defined as the number of products in on-hand serviceable inventory minus the number of products in backorder plus the total number of products that are currently manufactured and remanufactured reaches the level sin. The manufac- b PULL-disposal strategy. The manufacturing batch size is Qm.
Alternatively to this PULL-disposal strategy we have also investigated a variant with a fixed remanufacturing batch size. Numerical experiments showed that the difference between the two strategies is however small. Therefore, we restrict the discussion in this paper to the above implementation.
With PUSH control the start of the remanufacturing operation is solely based on the number of products in remanufacturable inventory, whereas under PULL control the start depends both on the inventory position and on the number of products in remanufacturable inventory. Furthermore, under the PUSH-disposal strategy the disposal decision depends on the inventory position, whereas it depends under the PULL-disposal strategy on the on-hand remanufacturable inventory.
The reason why in these two strategies the disposal decision is based on different inventories is that under PUSH control without planned disposals the inventory position and therefore the serviceable inventory is unbounded, i. In Section 3. The notation that we use in this outline is specified in Table 1. For ease of explanation we have restricted the scope of the outline to the situation with uncorrelated and exponentially distributed demand and return interoccurrence times.
For the modifications required to model correlations and Coxian-2 distributed demand and return inter-occurrence times we refer to Van der Laan et al. More complicated is the calculation of the average on-hand serviceable inventory and the average backorder position, i.
If the manufacturing lead time is larger than the remanufacturing lead time, all of the remanufacturing batches and none of the manufacturing batches that were ordered during time t -Lmax, t -Lmin ] will arrive before or at time r We model this by defining the binary variable 6, which is assigned the value 1 if the manufacturing lead time is larger than the remanufacturing lead time, and 0 otherwise.
The transition rates of. To calculate this probability we evaluate the transient behaviour of the Markov chain. The numerical study starts out from the base-case scenario which is defined below. Base-case scenario. Regarding the characteristics of the remanufacturing, manufacturing and disposal process we make the following assumptions: Process Systems with disposals vs.
It has been argued that the decrease in total expected system costs is a direct consequence of the cost structure in the base-case scenario, where variable remanufacturing costs are lower than variable manufacturing costs.
Furthermore, the increase in total expected system costs is due to a higher variability in the succeed in reducing the variability in the inventories. In particular, the PUSH-disposal strategy helps to reduce the variability of the net serviceable inventory Figs. The difference between strategies with and without product disposal becomes larger when the system uncertainty increases.
For example, Fig. PUSH-disposal vs. PULL-disposalIn [ 3 ] it has been demonstrated for the case without product disposals, that the PULL strategy outperforms the PUSH strategy with respect to the total expected system costs when remanufacturable inventory is valued lower than serviceable inventory. Additional experiments and Fig. Finally, it has been shown that the return rate at which the cost decrease changes into a cost increase mainly depends on how manufacturing costs, remanufacturing costs, and inventory holding costs relate to each other.
Production Planning and Inventory Control in Pharmaceutical Manufacturing Process – PDF download
Production Planning and Control draws on practitioner experiences on the shop floor, covering everything a manufacturing or industrial engineer needs to know on the topic. It is written in an approachable style, thus making it ideal for readers with limited knowledge of production planning. End of chapter questions help readers ensure they have grasped the most important concepts. MSc students and researchers working on manufacturing and industrial engineering topics, manufacturing engineers and others working in factories in roles related to PP and C. Elements of Production Planning and Control 2. Factory Planning 3. Factors for Production 4.
Production planning is the planning of production and manufacturing modules in a company or industry. It utilizes the resource allocation of activities of employees, materials and production capacity , in order to serve different customers. Different types of production methods, such as single item manufacturing, batch production , mass production , continuous production etc. Production planning can be combined with production control into production planning and control, or it can be combined with enterprise resource planning. Production planning is the future of production. It can help in efficient manufacturing or setting up of a production site by facilitating required needs.
PDF | This paper addresses a non-linear optimization model by integrating production planning and inventory control in the automotive industry.
MRP, JIT, OPT, FMS?
Managers of manufacturing companies are being suddenly confronted these days with an array of new systems to improve production efficiency. Will it be materials requirements planning, kanban, or optimized production technology? Or how about the latest approach—flexible manufacturing systems? As in many areas of business, choosing the best operations management technique making trade-offs.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Laan and M. Salomon and R. Dekker and L.
In this paper formulae are derived to give the optimum run lengths on a plant producing two products alternately. The general case of n runs of one product to one run of the other is considered. The work is applied to a chemical plant and the difficulties of determining certain costs are discussed.
Ее зовут… Не отключайся, дружище… - Роса… - Глаза Клушара снова закрылись. Приближающаяся медсестра прямо-таки кипела от возмущения. - Роса? - Беккер сжал руку Клушара. Старик застонал. - Он называл ее… - Речь его стала невнятной и едва слышной. Медсестра была уже совсем близко и что-то кричала Беккеру по-испански, но он ничего не слышал. Его глаза не отрывались от губ Клушара.
- Мне нужно в туалет. Хейл ухмыльнулся, но, подождав еще минуту, отошел в сторону. - Извини, Сью, я пошутил. Сьюзан быстро проскочила мимо него и вышла из комнаты. Проходя вдоль стеклянной стены, она ощутила на себе сверлящий взгляд Хейла. Сьюзан пришлось сделать крюк, притворившись, что она направляется в туалет.
Офицер был шокирован. - Вы же только что прибыли. - Да, но человек, оплативший авиабилет, ждет. Я должен доставить эти вещи. На лице лейтенанта появилось оскорбленное выражение, какое бывает только у испанцев.
Затем он его уничтожит, и Цифровая крепость навсегда исчезнет из Интернета.
Глаза его расширились. Это явно не было составной частью плана. - У них там прямо-таки дискотека! - пролопотал Бринкерхофф. Фонтейн смотрел в окно, пытаясь понять, что происходит.
- Джабба сунул в рот кусочек сыра моцарелла. - Кроме всего прочего, вирус просто не может проникнуть в ТРАНСТЕКСТ. Сквозь строй - лучший антивирусный фильтр из всех, что я придумал.