Journal of Materials Processing Technology 164–165 (2005) 1160–1166 Experimental and numerical analysis of metal injection molded products C. Binet a , D.F. Heaney a , R. Spina b, ∗ , L. Tricarico b a Center for Innovative Sintered Products (CISP Lab), 147 Research West, University Park, PA 16802, USA b Department of Mechanical and Management Engineering, Politecnico di Bari, Viale Japigia 182, 70126 Bari, Italy Abstract In this work, the authors performed the experimental and numerical study of a real product realized with metal injection mold- ing. The feedstock material (AISI 316 powder and binder) was initially characterized with specific tests in order to identify viscosity, pressure–volume–temperature and thermal properties. This data were then elaborated using a genetic algorithm approach to fit mathematical material models to use for finite element analysis with a commercial software normally employed for thermoplastic injection molding. At the same time, real part fabrication was performed with the process parameters used for numerical simulations in order to validate numerical results from qualitative and quantitative point of view. © 2005 Elsevier B.V. All rights reserved. Keywords: Metal injection molding; Finite element method; Material characterization; Genetic algorithms 1. Introduction Metal injection molding (MIM) is a net-shape process to produce relative small solid metal parts with high complex geometries. The MIM process consists of four steps such as mixing, injection molding, debinding and sintering. Small- sized metallic powder is initially mixed with a wax–polymer binder to form a homogeneous feedstock and the feedstock is shaped a mold. After removal the resulting green part from the mold, the wax–polymer binder is removed by heating and sintered (solid-state diffused) in a controlled atmosphere furnace in similar way to traditional powder metallurgy. MIM products are various and range from consumer prod- ucts, office equipment, medical instruments and automotive components to industrial processing equipment [1]. MIM combines benefits of the design freedom of processes such as plastic injection molding and high-pressure die casting with the properties of metals similar to those of wrought materials. In addition, extensive finishing operations of the final parts, normally required by traditional metalworking technologies, are very limited for parts produced with MIM process. The main limitations are that only parts with small ∗ Corresponding author. Tel.: +39 080 5962 768; fax: +39 080 5962 788. E-mail addresses: dfh100@psu.edu (D.F. Heaney), r.spina@poliba.it (R. Spina). dimensions can be realized and the binder removal task is very time consuming if part thickness is greater than 5 mm [1]. The main research trends of MIM are related to increase the use new metal powders and feedstocks in order to obtain better mechanical properties, improve material characteriza- tion method, optimize the process parameters for improving quality of molded products and simulate MIM process via finite element (FE) method to shorten time-to-design and re- duce experimental tests. The improvement of the metal feed- stock characteristics is obtained by mixing different material types (lubricant into the wax–polyethylene binder) to secure a quickly solvent-removable binder [2]. In addition, feedstock must be characterized to achieve reliable numerical simula- tions of the MIM process [3]. The characterization of material feedstocks is crucial to better understand MIM process and obtain consistent results with numerical simulations. The fol- lowing step is the optimization of the process parameters to produce MIM parts without defects and with required me- chanical properties by using experimental tests coupled to numerical modeling [4] or artificial intelligent methods [5]. The MIM process steps involved in the numerical simulations can be only the shaping one or the complete process [6]. This paper presents the analysis of a real product fabri- cated with MIM process. The main phases of the analysis were the following: (i) characterization of the feedstock ma- 0924-0136/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2005.02.128