**1. Introduction**

Plastic injection molding (IM) is one of the most important polymer processing operations in the plastic industry nowadays. The application of this process is increasing significantly in many fields, especially in the automotive parts. The most process injection molding parameters that analyze the mechanical properties are pressure, temperature, and time.

Experimental and-error approach to control the process parameters for injection molding is no longer effective. Wrong selection of these parameters induces a drop in the mechanical properties of injected molded parts [1–6].

Such problems can be solved by first developing optimization models correlating the responses and the process parameters. Optimizing these parameters requires a careful endeavor. Besides, the method of varying one parameter while keeping the others constant contains limitations such as the long time experience and the large number of experiments which raise its cost in order to get an important quality of the parts. Hence, a suitable optimization technique using design of experiment DOE by Taguchi approach is then applied to search for fine tuning of parameter values to obtain the desired responses. The Taguchi method introduces an integrated approach that is simple and efficient for finding the best range of designs for quality, performance, and computational cost [7–9]. Taguchi method is a useful methodology for analyzing the variation using the signal-to noise (S/N) ratio. The Taguchi analysis of the S/N ratio specifies three situations of quality characteristics, as well as the-largerthe-better (LB), the nominal-the-better (NB) and the-smaller-the-better (SB).

A great deal of research used this approach is being carried out to understand, identify critical factors and to optimize the molding process. For example, Wegrzyn et al. conducted a study to investigate the impact of injection speed and melt temperature on electrical conductivity and dynamic mechanical properties of PC/ABS-MWCNT Nano composites [10]. These authors figured out that the injected molded specimens recover conductivity. In addition, Wang et al. elaborated experimentally the compression behavior of PC/ABS during monotonic and cyclic loading over a wide-ranging of temperatures (up to 373 K) and strain rates (up to 5000 s−1) [11]. In parallel, Li et al. analyzed effect of process parameters namely, melt temperatures, injection speed and injection pressure to determine the influence of weld lines on appearance of PP products using Taguchi experimental design method [12].

Rafizadeh et al. showed that when fixing the mixing time and temperature, temperature and pressure of injection, mold temperature, and blend composition in mixing through the Taguchi orthogonal array, the impact strength of PC/ABS blend could be optimized [13]. Equally, Ozcelik studied the influence of the injection parameters and weld line on the mechanical properties of polypropylene (PP) during IM process via the design of experiment (DOE). Mechanical properties such as maximum tensile load, extension at break and charpy impact strength (notched) of the specimens were measured [14]. Furthermore, Kuram et al. discussed the tensile and the flexural strength during injection molding of virgin and recycled PBT/PC/ ABS blends using Taguchi experimental design. The results showed the impact of injection pressure, holding pressure, and injection temperature on the mechanical properties of the molded parts [15]. Aditya M. Darekar used the Taguchi approach and found that quality and mechanical properties parts are mainly caused due to improper selection of the processing conditions during production [16].

In this study, the effect of the injection molding process on the mechanical properties of the injected PC/ABS parts was investigated. The Taguchi method was used to find out the optimal combinations of the injection molding (IM) parameters that provide better mechanical properties. These results are considered interesting especially in the automotive industries. We intend to reduce the rejection rate caused by the surface quality of some injected PC/ABS parts.
