Impact of drilling parameters on the surface roughness of egg shell filled glass fibre/polyester composites

Abstract Glass fiber-reinforced polymers (GFRPs) are widely used in domestic applications such as doors, windows, and furniture, where drilling is a common machining process. The surface roughness of drilled hole walls is a critical factor, particularly in fastening applications, where smooth finishes are essential. This study explores the influence of drilling parameters on the surface roughness of GFRPs reinforced with different types of eggshell fillers viz.,un-carbonized, carbonized, and hybrid along with an unfilled variant. The research employs a Central Composite Design within the Response Surface Methodology (RSM) framework to investigate the effects of material type, spindle speed, feed rate, and point angle on surface roughness. Material type and point angle were treated as categorical variables, while spindle speed and feed rate were continuous, each with four levels, resulting in 16 experimental runs. The results showed that surface roughness values varied from 3.04 to 4.99μm, depending on the specific combination of drilling parameters. Statistical analysis using Analysis of Variance (ANOVA) confirmed that spindle speed and feed rate significantly impact surface roughness, with roughness increasing at higher speeds and feeds. Notably, the carbonized eggshell-filled GFRP variant achieved the lowest surface roughness. The study also developed a highly accurate regression model, validated through experimental data. The novel use of different variants of eggshell fillers in GFRPs provides a sustainable and effective way to enhance material properties. Further, conducting the drilling studies to observe the outcomes, offers potential industrial applications in the production of high-quality, durable composite materials.