ORIGINAL Evaluation of process parameters for lower surface roughness in wood machining by using Taguchi design methodology Sebahattin Tiryaki 1 • Cos ¸kun Hamzac ¸ebi 2 • Abdulkadir Malkoc ¸og ˘lu 1 Received: 31 January 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract This paper presents a study of the Taguchi de- sign method for obtaining lower surface roughness values in terms of process parameters in wood machining. The pro- cess parameters considered were feed rate, cutting depth, number of knives, annual ring (earlywood–latewood) and grit number of abrasive. The settings of the process pa- rameters were determined by using Taguchi experimental design method. Orthogonal arrays of Taguchi and the signal- to-noise (S/N) ratio were employed to find the optimal levels and to analyze the effect of process parameters on surface roughness. In addition, the Pareto ANOVA analysis was used in order to measure the influence of each process pa- rameter on surface roughness. The results of Taguchi ana- lysis revealed that the most significant variable on surface roughness of both beech and spruce woods by S/N ratio analysis and Pareto ANOVA analysis is the grit number of abrasive. It was also understood that the Taguchi design technique is very suitable to solve the surface quality problem regarding machining of wood species. 1 Introduction Wood products are formed after various machining pro- cesses. It can be said that planing operation is among the most important of the processes (Gurleyen 2010). In the machining process, process parameters such as cutting speed, cutting depth, feed rate, and tool geometry sig- nificantly influence the surface quality of wood subjected to machining (Lu 2008). In addition to the process pa- rameters, the surface quality of machined wood also de- pends on its anatomical structure, since it contains cell cavities that are independent of any machining process (Taylor et al. 1999; Gurau et al. 2005). Therefore, it is important to consider the parameters related to machining conditions and wood characteristics for improving the surface quality of the final product in wood machining (Gurleyen 2010). Otherwise, rough wood surface adversely affects further manufacturing processes such as finishing, strength characteristics, joint or bonding quality in the preparation of the final product (Sulaiman et al. 2009). To eliminate such problems, the sanding operation is the method most commonly used prior to applying wood fin- ishing (Koch 1964; William and Morris 1998; Sulaiman et al. 2009). Sanding operation makes the surface homo- geneous and reduces the influence of the anatomical structure on the roughness profile of wood surface and thus the surface can absorb the finishing materials better (Richter et al. 1995). A large number of experimental studies on the surface profile and roughness of machined wood have been carried out. Ors and Baykan (1999) reported that the smoother surface in the planing process was obtained with increasing number of knives. Usta et al. (2007) observed that the smoother surfaces were obtained by planing as cutting depth and feed rate decrease and number of knives in- creases. Sulaiman et al. (2009) investigated the effects of sanding operation on surface roughness of wood. They observed a better surface quality with increasing grit number of abrasive in sanding operation. Similar results were also reported by Aslan et al. (2008). These studies & Sebahattin Tiryaki sebahattintiryaki@hotmail.com 1 Department of Forest Industry Engineering, Faculty of Forestry, Karadeniz Technical University, 61080 Trabzon, Turkey 2 Department of Industrial Engineering, Faculty of Engineering, Karadeniz Technical University, 61080 Trabzon, Turkey 123 Eur. J. Wood Prod. DOI 10.1007/s00107-015-0917-x