Effect of wall thickness and cutting parameters on drilling of glass microballoon/epoxy syntactic foam composites
Introduction
Syntactic foams (SFs) are a special class of particulate composites developed by incorporating the rigid hollow particles in a matrix medium [1], [2], [3]. Syntactic foams are most commonly used in various marine, aerospace, automobile and civil structural applications owing to their low density combined with excellent compressive properties and low moisture absorption. These closed cell foams are also used in electronic packaging and insulation due to high thermal stability [3]. Hollow particles (also called microballoons) of glass, metal, polymers, carbon, ceramics and fly ash cenospheres have been used in SF fabrication [4], [5], [6], [7], [8], [9], [10], [11], [12]. Among different available hollow particles, glass microballoons (GMBs) are the most commonly used as compared to naturally available cenospheres due to better surface morphology [4]. Incorporation of these GMBs offers a wide range of properties to SFs like reduced density, improved impact strength, thermal and dimensional stability [13].
Epoxy resin with GMBs as fillers are extensively investigated for compressive, tensile, flexural, electrical and thermal properties in the recent past [14], [15], [16], [17], [18], [19], [20], [21]. Studies on the compressive properties reveal that the strength increases with density. Variation of filler content is not having any significant effect on the compression strength of the syntactic foam. Compressive modulus of syntactic foam depends on the GMBs wall thickness and found to be increasing with increasing content of thick-walled particles [14], [15], [16], [17]. Tensile test of syntactic foams reveals that the modulus and strength are found to be increasing with decreasing microballoon content. Modulus and strength can be improved by using thick-walled hollow particles [14], [18], [19]. Thermal studies reveal that incorporation of GMBs in epoxy helps to reduce the coefficient of thermal expansion and increases dimensional stability. It is also found that the dimensional stability of syntactic foam can be increased by increasing the wall thickness of GMBs [20], [21].
Structural components in weight sensitive applications of aerospace and automobile industries demand assembly of syntactic foams requiring drilling operation. However, syntactic foams drilling is quite challenging as drill experiences variable resistance while passing through the matrix, wall thickness of GMB and void space within GMB. Such variations in resistance might affect drilled hole quality significantly and hence needs to be addressed. Further, abrasive nature of GMBs may result in tool wear which significantly deteriorates the hole quality. Hence, the drilling behavior of syntactic foams needs to be thoroughly studied particularly in case of GMB wall thickness variations.
A number of research publications for evaluating the drilling behavior of polymer composites have been published. El-Sonbaty et al. [22] analysed the effects of cutting and work material parameters on torque, thrust force and roughness in glass fiber reinforced polymer (GFRP) drilling using high-speed steel twist drills. Gaitonde et al. [23] established the relation between speed and feed with surface roughness in high-speed drilling of polyamides using response surface methodology (RSM). For the same polyamide material, Rubio et al. [24] used Taguchi method to analyse the effects of tool geometry and cutting parameters on thrust force, circularity error and hole diameter. Liu et al. [25] optimized the cutting parameters in machining of titanium alloy under minimum quantity lubrication condition using a new flexible method called coupling response surface methodology. Results show that surface roughness and cutting forces can be minimized by adopting lower values of feed and depth of cut. Taguchi method coupled with GRA has been used by Palanikumar et al. [26] to optimize the process parameters for minimizing the surface roughness and thrust force in GFRP composite drilling. The effect of multi-walled carbon nanotube (MWCNT) in laser drilling of MWCNT reinforced GFRP nanocomposite composites has been reported by Palanikumar [27]. Results show that the addition of MWCNT significantly improves the hole quality due to enhanced heat transfer characteristics of the composite. Basavarajappa et al. [28] proposed RSM based mathematical expressions to correlate v and f with Ft, Ra and Kf for GFRP composites drilling.
Krishnaraj et. al. [29] conducted high-speed drilling of carbon fiber reinforced polymer (CFRP) laminates to analyse process parameters influence on thrust force, circularity, delamination, and hole size. Furthermore, multi-response optimization has been performed to improve the quality of drilled holes [30]. The effect of cutting speed and feed on drilling forces, burrs, hole wall surface morphology and delamination damage in drilling of high-strength T800S/250F CFRP laminate has been analysed by Xu et al. [31] using coated twist and dagger drill. Xu et al. [32] proposed evaluation criteria for quantifying the defects induced during drilling of T800/X850 CFRP laminates using three different types of drills. The effect of different cutting sequence, tool geometry and tool materials in drilling of hybrid CFRP/Titanium stacks have been studied by Xu and El Mansori [33]. Results reveal that the drill geometry significantly effects drilling of CFRP/Titanium stacks than tool material composition. Drilling from titanium to CFRP phase produces sound quality holes in terms of consistent hole diameters and better surface finish. Ameur et al. [34] analysed the effect of process parameters on cylindricity error and delamination in dry drilling of CFRP composites. Saoudi, Zitoune [35] proposed a unique analytical model for predicting critical thrust force responsible for delamination considering the effect of the chisel and cutting edges in drilling of CFRP composites. Effect of cutting speed and feed on the temperature generated during drilling of CFRP and GFRP composites has been reported by Sorrentino, Turchetta [36]. Finally, a numerical model has been proposed based on experimental data for predicting the temperature generated during drilling of composites. An effort has been made by Merino-Perez et al. [37] to study the effect f, v and workpiece constituents in CFRP composites drilling.
Despite the availability of exhaustive literature on drilling of polymer composites, studies influence of wall thickness variations (different density particles) on epoxy based syntactic foams is not yet reported. Thereby in the present investigation, an effort has been made to analyse the drilling behavior of GMB/epoxy syntactic foam with particle wall thickness variation. Influence of process parameters (v, f, w and D) on responses such as Ft, Ra, Kf, CYL, Ce-Exit and Fd-Exit are presented. Furthermore, based on the experimental analysis, grey relation optimization is performed to propose a specific combination of process parameters to achieve better machinability and hole quality which might act as a guideline in industrial practices.
Section snippets
Constituent materials
Syntactic foams specimens are fabricated using GMBs reinforced in LAPOX (L-12) epoxy resin with K-6 polyamine hardener procured from Atul Ltd., Valsad, India. Epoxy matrix is reinforced with three different density grades (particle wall thickness variations) of hollow borosilicate GMBs (SID-200Z, SID-270Z and SID-350Z) procured from Trelleborg Offshore, USA. Wall thickness, density and mean particle size of SID-200Z, SID-270Z and SID-350Z grade hollow particles are 0.716, 0.925, 1.080 µm; 200,
Syntactic foam microstructure and density
Extensive micrography is conducted on the as-cast syntactic foam samples. Fig. 2 shows a representative micrograph of as cast syntactic foam sample. Microballoons are observed to be uniformly distributed throughout the epoxy matrix without forming the clusters. Particle debris is not seen in the epoxy matrix indicating intact particles during processing. During syntactic foam fabrication air is entrapped in the matrix resin leading to matrix porosity. Densities of syntactic foams along with
Conclusions
Three types of syntactic foams are prepared using different grades of GMBs (varying wall thickness) in the epoxy matrix at 60 vol%. Fabricated syntactic foams are drilled using CNC vertical machining center with coated tungsten carbide twist drills. FFD based experiments are performed to analyse the effect of process parameters on the machining performance. Mathematical models developed based on experimental results to predict the responses in the chosen range are validated using ANOVA.
Acknowledgment
Authors thank the Mechanical Engineering Department at NITK for providing facilities and support. The views expressed in this article are those of authors, not of funding agencies.
Data Availability
The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.
References (57)
- et al.
Quasi-static compressive response of compression molded glass microballoon/HDPE syntactic foam
Compos B Eng
(2018) - et al.
Effect of arctic environment on flexural behavior of fly ash cenosphere reinforced epoxy syntactic foams
Compos B Eng
(2018) - et al.
Compressive behavior of cenosphere/epoxy syntactic foams in arctic conditions
Compos B Eng
(2018) - et al.
Development of glass microballoon/HDPE syntactic foams by compression molding
Compos B Eng
(2017) - et al.
High temperature erosion behavior of plasma sprayed NiCrAlY/WC-Co/cenosphere coating
Surf Coat Technol
(2017) - et al.
Specific properties and fracture toughness of syntactic foam: effect of foam microstructures
Compos Sci Technol
(2005) - et al.
Quasi-static uni-axial compression behaviour of hollow glass microspheres/epoxy based syntactic foams
Mater Des
(2011) - et al.
Manufacturing and failure mechanisms of syntactic foam under compression
Compos A Appl Sci Manuf
(2004) - et al.
Preparation and physical properties of hollow glass microspheres-reinforced epoxy matrix resins
Mater Sci Eng, A
(2005) - et al.
Factors affecting the machinability of GFR/epoxy composites
Compos Struct
(2004)
Experimental investigation and optimisation in drilling of GFRP composites
Measurement
Optimization of machining parameters at high speed drilling of carbon fiber reinforced plastic (CFRP) laminates
Compos B Eng
Hole-quality evaluation in drilling fiber-reinforced composites
Compos Struct
Study of drilling-induced defects for CFRP composites using new criteria
Compos Struct
Experimental study on drilling mechanisms and strategies of hybrid CFRP/Ti stacks
Compos Struct
Critical thrust force predictions during drilling: analytical modeling and X-ray tomography quantification
Compos Struct
In process monitoring of cutting temperature during the drilling of FRP laminate
Compos Struct
Influence of workpiece constituents and cutting speed on the cutting forces developed in the conventional drilling of CFRP composites
Compos Struct
Assessment of factors influencing surface roughness on the machining of Al/SiC particulate composites
Mater Des
Drilling of fiber reinforced plastics: a review
J Mater Process Technol
A new method to reduce delaminations during drilling of FRP laminates by feed rate control
Compos Struct
A novel approach based on digital image analysis to evaluate the delamination factor after drilling composite laminates
Compos Sci Technol
Dry sliding wear of epoxy/cenosphere syntactic foams
Tribol Int
Delamination analysis in high speed drilling of carbon fiber reinforced plastics (CFRP) using artificial neural network model
Mater Des
Influence of machining parameters and new nano-coated tool on drilling performance of CFRP/Aluminium sandwich
Compos B Eng
Machinability analysis in drilling woven GFR/epoxy composites: Part I-effect of machining parameters
Compos A Appl Sci Manuf
Effect of machining parameters on tool wear and hole quality of AISI 316L stainless steel in conventional drilling
Procedia Manuf
Comparative study of surface roughness and cylindricity of aluminium silicon nitride material using MRA GMDH & pattern recognition technique in drilling
Procedia Mater Sci
Cited by (29)
Effect of curing agents and hollow glass microspheres on the compression properties of syntactic foams
2023, Journal of Materials Research and Technology3D printed functionally graded foams response under transverse load
2023, Results in MaterialsMulti-objective optimization of machining parameter in laser drilling of glass microballoon/epoxy syntactic foams
2023, Journal of Materials Research and Technology3D printing of glass microballoon–based syntactic foams
2023, Lightweight and Sustainable Composite Materials: Preparation, Properties and ApplicationsInfluence of a batch of hollow glass microspheres with different strength grades on the compression strength of syntactic foam
2022, Composites Science and TechnologyEpoxy/hollow glass microsphere syntactic foams for structural and functional application-A review
2022, European Polymer Journal