Study of Machinability in Drilling Operation of Enset–Sisal Hybrid Polyester Composite

Abstract

Due to their light weight, low density, high-specificity strength, and ease of fiber surface treatment, natural-fiber-reinforced composites are recognized as the most suitable materials for interior part applications. Moreover, natural fibers are widely accessible and environmentally friendly. The fabricated parts are assembled predominantly by fastening using drilled holes, which makes drilling operations common machining processes for the composite parts. Damage occurs at the entry and exit surfaces of drilled holes. In this study, hand layup procedures are used to create unidirectional and woven forms of 1:1 ratio enset (false banana)/sisal hybrid polyester composites that have been treated with 5% NaOH. The drill operation was performed using a computer numerical control (CNC) drill machine with high-speed steel twist drill. A Taguchi design tool was used to complete the analysis. The experiments were conducted at different levels of drilling speeds: 600, 1200, and 1800 rpm. Feed rates of 0.1, 0.2, and 0.3 mm/rev and drill bit diameters of 6, 9, and 12 mm were used. These were determined to be the study parameters that influenced the delamination factors (Fd) and surface roughness (SR) of the hybrid composite drilled parts. Delamination occurred at the entry and exit surfaces of the drilled holes, and surface roughness occurred at the inner surface of the sectioned drilled hole. The quality of the drilled holes was compared based on the delamination factor and the surface roughness, as analyzed by the 3D optical surface profiles.

ANN Based Estimation of the Defects Severity at the Drilling of GFRP/Ti Multilayered Composite Structure

“…Despite the fact that in many works, e.g. [2,3,6,8,13,15,29,43,48], it is indicated that the amount of delamination decreases with increasing cutting speed, its upper limit was restricted due to elevated temperature, which was established experimentally. Based on the recommendations of these works and our own experience gained in the industrial manufacture of spars, a variation interval of 7.5-19 m/min was adopted for the cutting speed, and 0.2-0.8 mm/rev for feed rate.…”

“…Various empirical models [10,18], approaches based on statistical analysis of variations (ANOVA) [4,42,43], and ANN models [19,20,44,45] were used to express such relationships. The ANN approach requires a large amount of experiments to generate training information, but it has clear advantages over the use of polynomial and other analytical models, the order of which, sufficient to describe the essential features of the functional relationships between the conditions and results of a complex process, can lead to overfitting, that is, to the appearance of false features.…”