Solving a New Multi-Period Multi-Objective Multi-Product Aggregate Production Planning Problem Using Fuzzy Goal Programming Kaveh Khalili-Damghani* Department of Industrial Engineering, Faculty of Industrial Engineering, South-Tehran Branch, Islamic Azad University, Tehran, Iran Ayda Shahrokh Department of System and Industrial Engineering, Industrial Management Institute, Tehran, Iran (Received: July 20, 2014 / Revised: November 12, 2014 / Accepted: November 13, 2014) ABSTRACT This paper introduces a new multi-product multi-period multi-objective aggregate production planning problem. The proposed problem is modeled using multi-objective mixed-integer mathematical programming. Three objective func- tions, including minimizing total cost, maximizing customer services level, and maximizing the quality of end- product, are considered, simultaneously. Several constraints such as quantity of production, available time, work force levels, inventory levels, backordering levels, machine capacity, warehouse space and available budget are also consid- ered. Some parameters of the proposed model are assumed to be qualitative and modeled using fuzzy sets. Then, a fuzzy goal programming approach is proposed to solve the model. The proposed approach is applied on a real-world industrial case study of a color and resin production company called Teiph-Saipa. The approach is coded using LINGO software. The efficacy and applicability of the proposed approach are illustrated in the case study. The results of proposed approach are compared with those of the existing experimental methods used in the company. The rela- tive dominance of the proposed approach is revealed in comparison with the experimental method. Finally, a data dic- tionary, including the way of gathering data for running the model, is proposed in order to facilitate the re- implementation of the model for future development and case studies. Keywords: Aggregate Production Planning, Goal Programming, Mathematical Modeling, Fuzzy Goal Programming * Corresponding Author, E-mail: k_khalili@azad.ac.ir 1. INTRODUCTION Aggregate production planning (APP) is a low- resolution and high-level plan for determining the work force level, production rate, back order level, inventory level, volume of hiring, volume of firing, over time work, under capacity working, and sub-contracting level over a medium or long period of time in an organization. Mar- ket demands and the production strategy in order to sat- isfy the demand are the main inputs of APP (Leung et al., 2003). Several methods and approaches including heuristics, mathematical formulations, and experimental methods have been proposed to handle APPs to date, and among them, the mathematical models have been successful as they can properly handle the real life situa- tions (Mirzapour Al-e-Hashem et al., 2012). Industrial Engineering & Management Systems Vol 13, No 4, December 2014, pp.369-382 http://dx.doi.org/10.7232/iems.2014.13.4.369 ISSN 1598-7248│EISSN 2234-6473│ © 2014 KIIE