EVALUATION OF SURFACE ROUGHNESS PARAMETERS (Ra, Rz) IN DRILLING OF MDF COMPOSITE PANEL USING BOX-BEHNKEN EXPERIMENTAL DESIGN (BBD)

Abstract

Medium Density fiberboard (MDF) panels are economic alternative to engineering materials because of their superior advantages in furniture industry. The degree of surface roughness of the MDF panel plays an important role, since any surface irregularities will reduce the final quality of the product. Design of experiments has been used to study the effects of the drilling parameters such as speed, feedrate, and drill diameter (input data's) used on the prediction of surface roughness (output response) on drilling MDF composite. The present work describes the development of mathematical models to predict the two surface roughness parameters namely average roughness(Ra),and mean peak to valley height (Rz) which were used to determine quantative surface characteristics of the panels. Experiments were performed under different drilling conditions of spindle speed, feed rate and drill diameter.Residual plots were constructed to analyze the variation between the experimental values and model values. Analysis of Variance (ANOVA) was employed to identify the level of importance in drilling parameters on their performance characteristics.The effect of these parameters on surface roughness has been investigated using Box-Behnken experimental design. Response contours were constructed for determining the optimum drilling condition for the required surface roughness. The developed model establishes a correlation between speed, feed rate and drill diameter that influence the surface roughness in a MDF panel. Analysis of variance (ANOVA) is employed to study the surface roughness characteristics in drilling operation of MDF board. The analysis of variance showed high coefficient of determination (R 2 ) value of 0.99 and 0.9842 for Ra and Rz respectively, thus ensuring a satisfactory adjustment of the second order regression model with experimental data. The verification experiment is carried out to check the validity of the developed model. The surface roughness of the predicted model during the confirmatory test has 2.06% and 2.631% error for Ra and Rz respectively, which is well within the tolerable limits.

Experimental Study of Surface Roughness of Wood Plastic Composites after Turning

“…In the case of large content of pulp fibre (over 70%) it is possible to machine materials with use of conventional tools for woodworking. (Prakash et al, 2011): The article assessed parameters of surface roughness Ra (Rz) after drilling of composite boards with high content of wood, resulting in a clearly expressed conclusions: state of surface roughness decreases with the increasing feed rate, however, with the increasing spindle speed the state of surface after machining gets better. Statistical evaluation suggests a significant impact of the feed rate on the output characteristics assessing the state of the surface.…”

“…On the other hand the surface roughness improves with the increasing cutting speed. The delamination factor Fd was evaluated similarly (its value increases with the increase of feed rate and it decreases with the increase of cutting speed) [3,4,5,6].…”