Azwan Iskandar Azmi

Delamination and Surface Roughness Analyses in Drilling Hybrid Carbon/Glass Composite

Previous attempts at drilling of fibrous composites have been challenging due to the limited mechanical properties and presence of severe delamination damage at the top and bottom surfaces of the drilled hole. With the recent introduction of hybrid carbon/glass fiber reinforced polymer (HFRP) composites in both research literature and industrial applications, the need for evaluating their drillability is inevitable prior to their final usage. This is mainly because of the unique properties of HFRP composites as compared to the single-type FRP composites. Therefore, this paper aims to present a research initiative that will elucidate the high-range parametric effects of drilling control factors on delamination damage and surface quality. Taguchi methodology and statistical analysis of variance were applied to determine the performance of the drilling process. Experimental results revealed that delamination damage and surface quality values were strongly influenced by the feed and special tool geometries rather than the spindle rotational speed. Changes in the feed are likely to contribute to increase in the thrust force and strain rate on the workpiece. Confirmation tests have shown the closeness of the calculated values via a regression model and additive rule with the experimental values. This indicates that the regression model from the response surface can be employed to estimate delamination damage and surface roughness during drilling of HFRP composite.

Effect of Al2O3 nanolubrication with Sodium Dodecylbenzene Sulfonate (SDBS) on surface roughness and tool wear under MQL during turning of Ti-6AL-4T.

The application of coolant reduces the friction and heat generation, which affect the surface finish and tool life, during machining. Recently, nanolubricant opens a new ways of coolant strategy in machining operation. It is well known that suspended nanoparticles without surfactant in base oil tend to agglomerate after a period of time. This paper presents the effects of AEO3 nanolubricant with surfactant, Sodium Dodecylbenzene Sulfonate (SDBS) on surface roughness and tool wear during turning of titanium alloy, Ti-6AL-4T. The comparison of different coolant strategies, dry cutting, flooding, minimum quantity lubricant (MQL), nanolubricant with and without surfactant are also presented. The results showed that Al2O3 nanolubricant with surfactant, Sodium Dodecylbenzene Sulfonate (SDBS) under MQL exhibits low surface roughness and tool wear rate compared to others. This proved that the addition of surfactant not only improved nanolubricant stability but also machining performance.

Evaluations of Mechanical Properties and Residual Strength of Drilled Glass Fiber Reinforced Polymer (GFRP) Composites

This paper investigates the mechanical properties of drilled and non-drilled glass fiber reinforced polymer (GFRP) composites of plain woven and stitch bi-axial ±45° fabrics. Vacuum-assisted resin transfer moulding was employed to fabricate the composite panels. In the first stage of this study, mechanical properties such as tensile strength, flexural strength, and volume fraction of the composites were determined by per ASTM standards. Later on, the fabricated GFRP composites were drilled in order to investigate the delamination damage. Based on this issue, residual strength was evaluated after drilling process using constant feed rate and spindle speed but different drill bit geometries, which include twist drill bit and step drill bit. Experimental results showed that plain woven performed better in term of mechanical properties and residual strength after drilling process. In addition, residual strengths of drilled composites using step drill bit exhibited superior performance than that of the twist drill.

An Initial Study of the Effect of Minimum Quantity Lubricant of SiO2 Nanoparticle with PEG on Surface Roughness during Milling of Mild Steel

This paper study the effect of minimum quantity lubricant of SiO2 nanoparticle with surfactant, PEG on surface roughness during machining of mild steel. The application of conventional cutting fluid leads to techno-environmental issue such as environmental pollution. Nanolubricant consists of suspended nanoparticles in based fluid. Nanolubricant with surfactant creates stability of the particles in the base fluid. The results indicate the application of minimum quantity lubricant of nanolubricant with surfactant during machining process lead to minimum usage of cutting fluid and better surface roughness.

Tensile behaviour of open hole flax/epoxy composites: Influence of fibre lay-up and drilling parameters

The present study reports on a systematic experimental test that evaluates the effect of drilling parameters on the open-hole tensile properties of flax fibre epoxy reinforced laminates. Additionally, three lay-up configurations of the flax fibre, namely, [0°/90°]6, [0°]6 and [±45°]6, were investigated and compared. The results demonstrated that the [0°]6 lay-up configuration was superior in terms of mechanical or tensile strength retention of the composites given an 8u2009mm hole. Conversely, damage due to delamination was not significant due to the changes in feed rate and cutting speed. This suggests that the drilling parameters were less sensitive towards the mechanical strength of the flax fibre composites with the drilled hole. The less severity of the delamination can be attributed to the high fracture toughness (high mode I critical strain energy release) of the flax fibre when compared with that of the synthetic fibre reinforced composite counterparts. The use of the step drill bit design also potentially contributes to the reduced severity of the delamination damage to the flax fibre composites.

Machinability Study of Hybrid FRP Composite Using Abrasive Waterjet Trimming Technology

Machining of fiber reinforcement polymer (FRP) composite without any defect is extremely challenging when using conventional processes. This mainly due to its inherent anisotropic, heterogeneous, thermal sensitivity, and highly abrasive of nature of fiber reinforcement. Therefore, a kind of non-conventional machining process namely abrasive waterjet machining (AWJM) was endeavoured as it has been reported to be able to machine or cut almost any material included composites. In fact, previous research only provides partially desired parameters on machining these materials and mainly focuses on plain FRP composite. Therefore, this research attempted to evaluate the significant AWJM process parameters comprehensively on the main machinability output on the hybrid FRP composite. 2k factorial design and statistical analysis of variance (ANOVA) were applied to determine the performance of trimming process regarding surface roughness and delamination (entrance and exit). Experimental results revealed that the surface roughness was affected by the stand-off distance, abrasive flow rate, traverse rate rather than hydraulic pressure. Similar findings as to that of surface roughness were also observed for the top and bottom delamination damage.

Effects of machining conditions on the specific cutting energy of carbon fibre reinforced polymer composites

This article presents an approach to evaluate the effects of different machining conditions on the specific cutting energy of carbon fibre reinforced polymer composites (CFRP). Although research works in the machinability of CFRP composites have been very substantial, the present literature rarely discussed the topic of energy consumption and the specific cutting energy. A series of turning experiments were carried out on two different CFRP composites in order to determine the power and specific energy constants and eventually evaluate their effects due to the changes in machining conditions. A good agreement between the power and material removal rate using a simple linear relationship. Further analyses revealed that a power law function is best to describe the effect of feed rate on the changes in the specific cutting energy. At lower feed rate, the specific cutting energy increases exponentially due to the nature of finishing operation, whereas at higher feed rate, the changes in specific cutting energy is minimal due to the nature of roughing operation.

Optimization of Cutting Parameters for Surface Roughness under MQL, using Al2O3 Nanolubricant, during Turning of Inconel 718

Inconel 718 is a nickel-based alloy commonly used due to its excellent mechanical properties at high temperatures and its elevated corrosion resistance. This material however is difficult to machine due to the high temperature generated during machining, which requires efficient lubrication system. Minimum quantity lubrication (MQL) technique is a more efficient and a more environmentally friendly alternative to conventional flooding lubrication technique. The efficiency and efficacy of this lubrication technique can be further enhanced by adding nano particles and surfactant into the base lubricant. There are currently limited number of studies on the application of minimum quantity lubrication (MQL) technique using nanolubricant with added surfactant in the machining of hard-to-machine materials such as Inconel 718. Consequently, this paper aims to optimize the cutting parameters for surface roughness under minimum quantity lubrication (MQL) condition using surfactant-added Al2O3 nanolubricant during the turning of Inconel 718. The effects of cutting speed, depth of cut and feed rate and their two-way interactions on surface roughness are investigated on the basis of the standard Taguchis L9 orthogonal array (OA) design of experiment and the results are assessed using analysis of variance (ANOVA) and signal to noise (S/N) ratio methods to determine the optimal cutting parameter settings as well as the level of significance of the cutting parameters. The optimal surface finish can be observed at the cutting speed of 70 m/min, depth of cut of 0.05 mm and feed rate of 0.05 mm/rev with feed rate being the most significant factor to affect surface finish. Through this study, the application of minimum quantity lubrication (MQL) technique using surfactant-added Al2O3 nanolubricant, has been shown to produce desirable surface finish quality on Inconel 718 with additional economic and ecological benefits.