For comparison, the drilling behaviour of abaca fiber‐reinforced polymer (AFRP) composites and Kevlar‐reinforced epoxy polymer (KFRP) composites has been studied in the specified experimental condition. The different geometrical drilling tools have been used for the investigation, namely, candlestick (T1), core (T2), standard twist drill (T3), and step cone (T4). The tool feed of 30, 45, and 60 m/min and rotational speed of 1000, 1500, and 2000 rpm have been used for the investigation. The thrust force is chosen as a response parameter for this study. The results revealed that, at lesser rotational speed and tool feed, the thrust force has declined. The result obtained correlates with the abaca fiber‐based systems. However, the thrust force of KFRP is higher compared to AFRP composite systems. The axial force generated by candlestick drill is minimal compared to the other drill bits. The following may be responsible for lower thrust force: (1) the axial force distributes circumferential of the cutting tool instead of focusing at the center and (2) the interfacial adhesiveness between the matrix and the fiber is higher. The optimization of drilling process parameters, namely, tool feed and rotational speed on thrust force, has been studied. The results reveal that the tool feed contributed more to axial force compared to rotational speed.

The drilling process is the most essential in the final assembly of the mechanical parts. Natural fiber based composites replace traditional materials due to their advantages, such as strength to weight ratio, availability, and environmental hazards. In this work, an attempt has been made to find the minimum thrust force produced by the drill tool at specified drilling process parameters. The drilling process parameters used for the investigation are rotational speed, tool feed, and resins. The spindle speed and feed rate are selected with three levels. Three resin materials were used, namely, epoxy, polyester, and vinyl ester. Taguchi’s L₂₇ orthogonal array was implemented. The result shows that the candlestick drill bit generated lesser thrust force at the specified drilling process parameters, followed by the twist and step cone drill bits.

The present study aims in analyzing the mechanical behavior of natural fiber (abaca) reinforced polymeric composites under dynamic conditions. It is evident from the past research reports that natural fiber offers desirable physico-mechanical properties to the added polymers. In the present research work, abaca fiber is utilized for the preparation of composites due to its promising mechanical properties and resistance to salt water corrosion, its lignin content is 15% and grows up to 3 m. Abaca is extracted from leaf sheath of Manila hemp plant, it is a kind of banana family. Influence of temperature on the mechanical behavior of natural fibers needs to be identified to ensure its usage for high performance applications. Pure and chemically treated abaca fiber based vinyl ester composites are subjected to dynamic mechanical analysis (DMA). The reason for the chemical treatment of abaca fiber is to enhance its interfacial bonding with base matrix. Fourier transform infrared spectroscopy (FT-IR) analysis signifies the morphological changes in abaca fiber after chemical treatment. Storage modulus (E') and damping characteristics of abaca fiber reinforced vinyl ester composites are comparatively higher than in neat polymer. In addition, surface treatment of fiber demonstrates significant enhancement in storage modulus compound compared to pure and raw fiber reinforced polymer due to strong physical interaction between fiber and matrix.

In this work, the hybrid fiber-based epoxy composite samples have been prepared with the application of three unlike organic natural fibers viz., Sisal (S), Ramie (R), and Flax (F) and epoxy as the matrix, with a weight ratio of 70:30 for epoxy and fibers. Six different stacking sequences of fibers, pure fibers and pure matrix were used for specimen preparation, namely S/F/F/F/S, F/S/S/S/F, F/R/R/R/F, R/F/F/F/R, R/S/S/S/R, S/R/R/R/S, PS, PR, PF, and Pure matrix. The composite specimen was prepared by manually and uniform thickness was obtained by the compression moulding process. The mechanical trials such as, tensile, impact, hardness, and flexural tests had been carried out on the composite samples. The results revealed that among all the fiber-stacking combinations, the maximum tensile strength was observed in the Sisal and Flax fiber-based sequence F/S/S/S/F, showing a 366.7% enhancement compared to pure epoxy. The composite materials with the layering sequences R/S/S/S/R, F/R/R/R/F, and R/F/F/F/R demonstrate superior flexural strength, impact strength, and hardness values, respectively, compared to other combinations of composites. The maximum tensile, flexural, and impact strengths and hardness of F/S/S/S/F, R/S/S/S/R, F/R/R/R/F and R/F/F/F/R are 36.28 MPa, 77.8 MPa, 13.38 kJ/m², and 57 h, respectively, compared to all the remaining sequences of the specimens. Various defects in the composite specimens, including fiber breakage, porosity, voids due to fiber pullouts, and matrix regions, were identified through scanning electron microscope images.

In this study, thrust force generation during drilling in natural fiber-reinforced epoxy has been investigated. Three natural fibers Abaca (A), Hemp (H) and Jute (J) have been utilized. Four different point angles of the twisted drill tools have been employed: 90°, 100°, 105° and 118°. The sequence of natural fiber-based specimens prepared for the studies as follows: A/H/A/H and H/J/H/J. The objective of this study is to find the drilling process parameters at lower thrust force. Also find the percentage of contribution of the drilling process parameters on the thrust force. Few authors has studied the drilling analysis using angle variation in the twisted drill bit however, no researches has been found in the drilling study of Hemp, Abaca and Jute by different angled twist drill bit. The result indicates that at 0.05 mm/rev feed rate and 3000 rpm spindle speed generated minimum thrust force of 4.6 N on abaca and hemp-based composites using 90°-point angle of the twisted drill bit. At 0.05 mm/rev, 3000 rpm and 90°-point angle of drill bit, produced minimum thrust force of 3.1 N on Hemp and Jute fiber-based composite. Thermal imager has been used to monitor temperature variation during the drilling of composite specimens. Defects in the specimen was identified by using scanning electron microscopic and microscopic images. The analysis of variance of the thrust force generated during drilling of the A/H/A/H and H/J/H/J based composite materials has performed using Minitab 21 software.

The influence of process parameters on thrust force during the drilling of pure and chemically treated Kevlar reinforced epoxy composites has been investigated. Surface treatment has been carried out to enhance the physical bonding between fiber and matrix. Four different drill bits were used for the investigation: standard twist, core, step cone and candle stick drill. Three speed and feed rates were used for the investigation. Our objective was to find the minimum thrust force during the drilling of pure and chemically treated Kevlar reinforced composite using four different drill bits. Optimization of drilling process parameters was performed using the Taguchi method of L₉ Orthogonal Array. We found that among the four drills core and candle stick drills produce a minimum thrust force compared with the twist and step cone drills. Thrust force values produced by a chemically treated specimen is lower than that of a pure composite specimen irrespective of the drill bits used. Chemically treated specimens of the core and candle stick varieties are suitable for lower thrust force and delamination free holes under specified experimental conditions. The significance of feed rate is more important for thrust force during the drilling of composite specimens irrespective of drills.