A holistic approach to manufacturing systems modelling

Author(s):  
Dursun Delen
Author(s):  
Ömer Faruk Yılmaz ◽  
Mehmet Bülent Durmuşoğlu

There are three main problems that could impact the performance of a Hybrid Manufacturing System (HMS): (1) order release (OR), (2) batch scheduling and (3) worker assignment. This paper deals with these three main problems hierarchically for an HMS. Three different mathematical models are developed to describe the problems more clearly. A novel methodology is proposed to adopt a holistic approach to these problems and find an effective solution. Implementation of the proposed methodology permits integrating batch scheduling and worker timetabling. Feasible solutions in the best-known Pareto front are evaluated as alternative solutions. The goal is to select a preferred solution that satisfies worker constraints, creates effective worker teams in cells, minimizes the number of utility workers, and the average flow time. The study also presents several improvements, which are made following the application of the proposed methodology to a real company that produces expansion joints.


2008 ◽  
Vol 41 (3) ◽  
pp. 193-198
Author(s):  
Aurelian Stanescu ◽  
Dimitris Karagiannis ◽  
Mihnea A. Moisescu ◽  
Ioan S. Sacala ◽  
Valentin Manoiu

Author(s):  
Syed Waqar Raza ◽  
Ibrahim Mostafa Deiab

There is an increased interest in sustainability assessment of manufacturing systems and processes because of the growing global interest in sustainable manufacturing practices. The current sustainability assessment models present a holistic approach, e.g. LCA, without much focus on process specific details. This paper uses a ‘XSI’ approach for defining sustainability indices (e.g. Energy Sustainability Index, ESI). These sustainability metrics can quantify machining processes in terms of impact on the environment and power consumption in a flexible manner, so that various material removal processes can be rated on a uniform scale. In addition, the concept of Normalization, with respect to the ‘feature-of-interest’ is introduced, thus presenting a flexible rating system in terms of process types (turning, milling etc.) and perspectives (material removal, quality etc.). A user-friendly calculator is developed, which converts a set of inputs for the machining scenario into a set of measurable rating quantities and indices including but not limited to production rate, production cost, tool life/cost, energy consumption and environmental burden. This will enable the manufacturing engineer to make an informed decision about parameter selection and process design for sustainability. Machining of hard-to-machine materials such as Titanium Alloys is such a scenario, which is used as a case study to validate the proposed approach.


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