Thermo-Mechanical and Delamination Properties in Drilling GFRP Composites by Various Drill Angles

Abstract

This manuscript aims to study the effects of drilling factors on the thermal-mechanical properties and delamination experimentally during the drilling of glass fiber reinforced polymer (GFRP). Drilling studies were carried out using a CNC machine under dry cutting conditions by 6 mm diameter with different point angles of ∅ = 100°, 118°, and 140°. The drill spindle speed (400, 800, 1600 rpm), feed (0.025, 0.05, 0.1, 0.2 mm/r), and sample thickness (2.6, 5.3, and 7.7 mm) are considered in the analysis. Heat affected zone (HAZ) generated by drilling was measured using a thermal infrared camera and two K-thermocouples installed in the internal coolant holes of the drill. Therefore, two setups were used; the first is with a rotating drill and fixed specimen holder, and the second is with a rotating holder and fixed drill bit. To measure thrust force/torque through drilling, the Kistler dynamometer model 9272 was utilized. Pull-in and push-out delamination were evaluated based on the image analyzed by an AutoCAD technique. The regression models and multivariable regression analysis were developed to find relations between the drilling factors and responses. The results illustrate the significant relations between drilling factors and drilling responses such as thrust force, delamination, and heat affect zone. It was observed that the thrust force is more inspired by feed; however, the speed effect is more trivial and marginal on the thrust force. All machining parameters have a significant effect on the measured temperature, and the largest contribution is of the laminate thickness (33.14%), followed by speed and feed (29.00% and 15.10%, respectively), ended by the lowest contribution of the drill point angle (11.85%).

Recent Advances in Drilling Tool Temperature: A State-of-the-Art Review

“…Sorrentino [34] Battaglia [36] Li [37] DeVries [35] Weinert [33] Cardoso [40] Bağci [32] Bono [42] Bono [41] Drill-foil Thermocouple Bhowmick[52] TASKESEN [53] Ueda [43] Yang [44] Pérez [39] Dörr [56] Usama A [57] Reissig [25] Mills [26] Wright [27] Okada [46] Oezkaya [55] Beno [47] obtain drilling temperature remotely. There are many non-contact measurement methods, but the methods used in drilling are completely limited to infrared radiation.…”

Heat-Affected Zone and Mechanical Analysis of GFRP Composites with Different Thicknesses in Drilling Processes

“…Figure 13 shows some representative samples of peel-up and push-out delaminations at different feeds, speeds, and laminate thicknesses. Push-out delamination is higher and more critical than peel-up because of the lack of backup support, compensating for the thrust force during drill penetration [14,15,46]. On comparing Figure 13a with Figure 13b, it is evident that at the same cutting condition, the push-out delaminations of the GFRP laminate with a 7.7 mm thickness are higher than those of specimens with a 2.6 mm thickness and accompanied by edge chipping, spalling, and uncut The largest induced temperature was observed in drilling specimens with a 7.7 mm thickness, as shown in Figure 9.…”

“…Bai et al [ 44 ] and Wang et al [ 45 ] proposed a novel mechanical model to predict a drilling thrust force with tool wear effects of unidirectional CFRP and a CFRP/Al stack. Khashaba et al [ 46 ] studied the influence of the drill bit point angle on the generated heat on a woven GFRP composite.…”

Evaluation of the Mechanical Properties and Drilling of Glass Bead/Fiber-Reinforced Polyamide 66 (PA66)-Based Hybrid Polymer Composites

“…[13]. The machinability of fiber-reinforced composites differs from fiber-only materials [14,15]. The mechanical-thermal characteristics of these materials have a significant effect on machinability [16].…”