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In order to determine the best sequence to be used for the assembly of a product, all the feasible sequences should first be identified and then they should be evaluated in order to select the best one. However, since there usually exists a large number of feasible sequences, an efficient and compact representation method is necessary. A representation method called the Assembly Sequence Graph is presented in this paper, which offers a useful tool to the engineers in the industry in order to conveniently represent all the feasible assembly sequences, and then to evaluate them using qualitative and quantitative criteria. An example has been provided to illustrate the proposed approach.

In this paper, integrated planning of production, imperfect maintenance and process inspections in a multi-machine system is investigated. This system consists of parallel machines which deteriorate with time and they may shift from a primarily in-control state to a degraded state with a higher defective rate or to a failed state. Maintenance scheduling corresponds to a discrete time age-based imperfect maintenance with a large number of maintenance alternatives. Process inspections are considered to detect the current state of the system. Detecting a deteriorated condition initiates the quality check of the related sub-lots, rework of defective items and a process adjustment that brings the machine in its normal conditions. Production planning includes a capacitated lot-sizing problem with multiple products. We propose a joint approach that coordinates the decisions of the three functions, where the objective function minimises the total cost. Evaluation of costs and interacting factors is presented and ...

This paper deals with the production planning problem of a flexible manufacturing system (FMS). This problem is within the class of problems which are usually faced during the life cycle of FMS. There are basically two approaches used to solve this problem: analytical and simulation. The objective of this paper is to develop a methodology for determine the control policy for a given FMS by using the combination of both analytical and simulation approaches. The production rate control of a one-machine one-product system is presented to illustrate our approach. The contribution of the analytical part of the proposed model consists of generating a near-optimal controller based on the concept of an age-dependent hedging point policy. This sub-optimal policy is used as input of the simulation part and the improvement of operating conditions (control policies) achieved with a constant demand rate. The proposed model includes also a stochastic demand and lot sizes in production which consists of similar products...

In the industrial field, the idea of subassembly must be distinguished from the subset one, when considering subassemblies as the only subsets in which all parts are stable. An original approach using the disassembly method, the logical reverse chronology of assembly, and the introduction of a mathematical model describing the liaisons allow us to determine the problems related to the automation of assembly sequences. To do so, the modelling of functional liaisons between parts helps to distinguish a simple contact from an attachment, and subsets from subassemblies. Liaisons between components are described by matrices of half degrees of liaison. These liaisons are extracted automatically from a B-rep model of a mechanical product on CAD. Subassemblies are determined automatically just in time during the determination of disassembly sequences. A limitation of this approach is that as soon as a relation is no more orthogonal to the basic referential, a new referential has to be introduced. An expert will c...

This paper presents a vendor-managed inventory (VMI) with consignment stock (CS) policy applied to the integrated vendor–buyer system, where the demand at the buyer side is stock dependent. Under the VMI with CS, the vendor manufactures a product and delivers it in batches of equal sizes to the buyer: although the goods are in the warehouse of the buyer, they remain to be the property of the vendor until the buyer registers a withdrawal. The products delivered are presented to the end customers in a display area and the demand is assumed to be positively dependent on the number of items displayed. Moreover, the model proposed considers that the product display area is replenished once its inventory level hits a given minimum. The paper investigates and compares different policies that may be adopted to exploit the advantages offered by the consignment stock agreement when stock dependent demand at the buyer side is considered.

There are different approaches to modelling the products at the End of Life (EOL), including closed loop approach, the ladder of lansink and material flow. The sustainability principles and the complexity of the products may affect the choice of modelling type. The life cycle costs, several subsystems and the interaction between design features, construction, technology, suppliers and legislation affect the degree of complexity of the products. Hence, developing appropriate strategies are required for modelling EOL phase of the complex products. This article presents strategies for modelling EOL phase of complex products considering sustainability tools, EOL phase models and the characteristics of these products. An ingenerated approach is proposed to address the four essential aspects of the complex product at the EOL: operational, tactical, strategic and sustainability. The case of aircraft at the EOL is presented to highlight the application of the proposed approach.

This research applies agent-based modelling (ABM) to study volume flexibility in a dual resource constrained (DRC) assembly flow shop environment. The simulation experiment evaluated system and human effects of varying DRC system staffing levels according to design (i.e., workforce, distance and buffer capacity), sensitivity (i.e. coefficient of variation) and operating (i.e. when rule and where rule) factors. Results showed that the rule by which workers are assigned to workstations affects WIP and flow time performances more than production rates. Furthermore per-worker productivity was found to increase, compared to the fully staffed system, particularly where the downstream movement rule was applied. Using the downstream rule when changing stations after completing current tasks reduced flow time (−15%) and WIP (−10%). If another where rule is chosen then it may be preferable for workers to move only after completing all jobs in the station (decentralised rule). For utilisation rates and mean hourly s...

This paper addresses the generic problem of production planning in a divergent timber production environment. It aims at analysing the performance of various demand-driven production strategies of a timber production system. This analysis is performed using a simulation platform built on an agent-based advanced planning system. Nine production strategies configurations are evaluated under six scenarios in order to carry out a complete mixed level design of 54 simulation runs. Each of these configurations is a combination of a decoupling point position and a level of capacity that is committed to contracts with customers. Accordingly, the six scenarios are designed as a combination of supply type (i.e. log diameter distribution) and timber market prices. Production processes and co-production yields are based on a real manufacturing system from eastern Canada. Performance is evaluated from the logistic and economic points of view. Results demonstrate that demand-driven planning approaches that propagate de...