The Study of CFRP Variable Feed Drilling Method Based on Sinusoidal Curve

In order to reduce the delamination damage of carbon fiber reinforced polymer (CFRP) drilling and improve the drilling quality. A variable feed drilling method based on sinusoidal curve was proposed, that is, when the drill at a distance of 1mm from the hole exit, the feed rate of the drill would be reduced according to the rule of sinusoidal curve. The method is compared with the traditional feed drilling by experiment, and the influence of the variable feed drilling on thrust force, delamination factor, surface quality, surface roughness of hole wall and exit hole wall morphology are analyzed. The results show that compared with constant-feed drilling, the variable-feed drilling based on sinusoidal curve reduces the thrust force near the hole exit, and greatly improves the delamination factor, surface quality and hole wall morphology at the exit. But the influence on the hole wall roughness is not particularly obvious.

Delamination ASSESSMENT during MACHINING OF laminated POLYMER nanocomposite

Nanomaterials are gaining extensive application in the manufacturing sector due to favorable properties. Its rapid growth in highly sensitive, robust, and lightweight sensors and biomedical components has attracted considerable attention worldwide. Nanomaterial uses with fiber-reinforced polymeric material have increased significantly. In order to manufacture structural components in a near-net shape, laminated nanocomposite machining is required. Due to the need for product assembly in mechanical structures, Milling is the primarily machining process in the manufacturing industry to create slots, channels, etc. The present work optimized the process variables affecting the Milling process by adopting the minimize criterion to control the delamination factor using the Taguchi method. The process parameters include cutting speed, feed, depth of cut, and filler material Graphene Oxide. The optimized conditions were found as cutting speed (Vc) 37.12 m/min, spindle feed (F) 80 mm/min, depth of cut (D) 0.5 mm and filler material Graphene Oxide (G) 1 wt.%. The percentage contribution of the process parameter on the delamination factor (Fd) was determined using the Analysis of Variance (ANOVA) method, and it has been found the feed rate (62.60%) is the most influencing factor. The delamination factor obtained in the confirmatory experiments carried out under optimized conditions was found lower than the Taguchi design test runs. The findings indicate that process parameter optimization under the given set of experimental conditions is effective for a manufacturing environment.

Mechanical Properties and Delamination Factor Evaluation of Cellulose (Nettle) Fiber Reinforced Polymer Composites using RSM

This paper discusses on fabrication, testing and evaluation of delamination factor of nettle fiber based composites for low duty applications. The randomly oriented nettle fibers were used to fabricate the biocomposite by conventional hand lap up technique. Epoxy and Nettle based composite plates were developed by varying fiber weight percentage from 5% to 25%. The flexural, tensile, impact, chemical resistance and water absorption rate of developed nettle fiber based biocomposite were examined for different fiber weight fractions in the randomly oriented patterns as a unique and innovative attempt. During the investigation, flexural strength and tensile strength were improved up to 20 wt% of fiber addition and then it was decreased. This resulted in a continuous rise in impact strength with an enhancement in fiber wt. %. The influence of fiber weight percentage on water absorption and chemical resistance of fabricated composite was examined in different environments. The result showed that the nettle fibers can be used as an essential reinforcing material to design and fabricate mechanical and structural members for low duty application. The chemical behavior of nettle based composite was studied by the FTIR spectroscopy method and the presence of chemical functional group was confirmed. The drilling behavior of developed nettle/SiC/epoxy hybrid composites was evaluated by consider cutting process parameters like feed rate (0.125, 0.212 and 0.3 mm/rev), spindle speed (400, 600, 800 rev/min) and drill diameter (4, 6, 8 mm). Analysis of variance was used in designing experiments for the current investigation. Feed rate was found to be a very impressive factor in influencing the delamination factor.

Parametric investigation on surface roughness and hole quality of Ti metal hybrid fibers cored laminate (MFL) during abrasive water jet drilling

High-strength environment-friendly metal-fiber laminates (MFLs) are increasingly used for primary structures for various engineering applications. The surface roughness variation and delamination factor of a titanium (Ti) metal-cored basalt/flax fiber laminate were investigated during abrasive water jet drilling (AWJD). The present AWJD investigation is to establish the correlation of four important process independent variables of WJP—water jet pressure, TS—traverse speed, QMFR—abrasive mass flow rate, and SOD—stand-off distance to the delamination factor (Fd-top) and surface roughness (Ra) of drilled hole. Central composite design (CCD) of L29 orthogonal array was used to perform the experimental observations. The statistical approach (ANOVA) was employed to determine the contribution of individual AWJD parameters to drilling operation. It is identified from experimental results that the water jet pressure is the most predominant process parameter and its contribution on Fd-top and Ra were 74.28% and 72.48%, respectively. Increasing the water pressure from low (160 MPa) to its higher range (320 MPa) showed that the surface roughness and delamination factor were reduced irrespective of other drilling parameters. Increased water pressure provides enough kinetic energy for abrasive particles to facilitate a higher penetration potential during the drilling process. Scanning Electron Microscope (SEM) images show the machining-induced damages like ploughing marks, uncut fibers, ridges, craters, matrix smearing, and delamination on an abrasive water jet drilled surface of prepared MFL.

EVALUATION OF THE EFFECTS OF DRILLING PARAMETERS, TOOL GEOMETRY AND CORE MATERIAL THICKNESS ON THRUST FORCE AND DELAMINATION IN THE DRILLING OF SANDWICH COMPOSITES

This study examined the effects of drilling parameters, tool geometry, and core material thickness (CMT) on thrust force and the delamination factor in the drilling of sandwich composites. Aluminum honeycomb (10 and 15[Formula: see text]mm in thickness) was used as the core material, with carbon fiber-reinforced polymer (CFRP) as the top and bottom surfaces. In the drilling experiments, three different cutting speeds (60, 78 and 100[Formula: see text]m/min) and two different feed rates (0.05 and 0.075[Formula: see text]mm/rev) were used. Drills having a diameter of 6.35[Formula: see text]mm and three different geometries (candlestick drills, twist drills and dagger drills) were used in the experiments. At the end of the experiments, thrust force was seen to increase with increased feed rate and CMT. Increased cutting speed generally decreased the thrust forces and the minimum thrust force was achieved with the 10 mm thick core material, 0.05[Formula: see text]mm/rev feed rate and 100[Formula: see text]m/min cutting speed using the dagger drill. The delamination factor at the entrance area was very low when drilling the sandwich composites and there was no significant difference based on drilling parameters, tool geometry, or CMT. Tool geometry was the main effective factor on exit delamination, and the highest delamination occurred with the use of the candlestick drill. Although increased feed rate increased delamination with all tools, with the dagger drill, increased cutting speed led to a severe increase. Delamination, tearing, and uncut fiber formation were observed when images of the exit areas of the drilled holes were examined.

Drilling induced delamination assessment of nanoparticles reinforced polymer matrix composites

The knowledge of polymer matrix composites machinability has increased with its rise in multi-field structural applications. Drilling of polymer matrix composites is required to achieve structural integration with greater accuracies. Delamination due to drilling affects the material strength and it occurs at both the entry and hole exit planes. The delamination on the exit plane is critical. The effect of nano-fillers on drilling-induced delamination of reinforced plastics has not been documented extensively and in this article, an attempt is made to explore the application potential of montmorillonite clay and graphene with amine functionalization in minimizing delamination through toughening the epoxy matrix. Experimentation was based on Taguchi’s L16 approach. The delamination factor and circularity ratio were analyzed using an image processing technique in Matlab and Image J. To evaluate the effects of various parameters and parameters interaction effect on the delamination factor, ANOVA was employed and Signal/noise ratios were calculated. The mathematical models were developed for delamination. It was observed that the reduction in the delamination factor was observed in nanoclay and graphene reinforced polymer matrix toughened composites in comparison to the base composites with a reduction in thrust force, specific cutting energy, and increase in circularity ratio.

Effect of the threaded nozzle on delamination and surface texture of PEEK CF30 composite machined by abrasive jet

Purpose The purpose of this study is to bring out the machining characteristics of abrasive jet machining on carbon fibre reinforced thermoplastic composites utilized in aerospace and biomedical applications. Biocompatibility materials such as carbon fibres and polyether thermoplastics, like polyether ether ketone (PEEK) are widely used in trauma and orthopaedic surgery. Due to the heterogeneity, layered construction of reinforcing phase bonds with a resin matrix and abrasiveness of the reinforcing fibre, traditional drilling of carbon fibre-reinforced composites (CFRPs) are always challenging task. Design/methodology/approach An investigation is carried out using abrasive jet machine for drilling PEEK filled with 30 Wt.% carbon fibre (CF 30) using threaded and unthreaded nozzle to study the effect of abrasive jet process variables on surface roughness (Ra) and delamination factor (DF). Pressure (P) and stand-off distance (SOD) as important technological abrasive jet factors were evaluated. It is found that higher abrasive jet pressure and minimum SOD maybe selected to achieve minimum delamination. Findings The study further reported that the threaded nozzle minimized the surface roughness by 43% and delamination factor up to 12%. Originality/value This study of experimenting and observing the machining characteristics of CF30 by using a threaded nozzle is being tried for the first time and the results are deliberated.

Experimental and Scale-span Numerical Investigations in Conventional and Longitudinal Torsional Coupled Rotary Ultrasonic Assisted Drilling of CFRPs

Longitudinal torsional coupled rotary ultrasonic assisted drilling (LTC-RUAD) technology is introduced to improve the surface roughness of the hole wall and solve the tear, burr and delamination of carbon fiber reinforced polymers (CFRPs) induced by large thrust force and torque during conventional drilling (CD). An experiment and scale-span numerical investigation of drilling CFRPs was presented for both CD and LTC-RUAD process in this study. A drilling experimental platform using LTC-RUAD was built via a novel independently designed and manufactured LTC-RUAD vibration actuator, while the drilling experiments involving T700S-12K/YP-H26 CFRPs specimens with different process parameters were carried out by adopting the different ultrasonic vibration amplitude (UVA) in the longitudinal and torsional directions. Then, a three-dimensional (3D) scale-span FE simulation model of CD and LTC-RUAD which applied the different UVA using tapered drill-reamer (TDR) are developed to find more details about the effects of machining quality of the holes. Experimental and simulation results revealed that the maximum average thrust force reduction is observed to be as high as 30% under certain drilling conditions, and the maximum average thrust force and the delamination factor of the drilled hole shows a "concave" trend with the increase of the UVA. The quality at the exit of the drilled hole is the best when adopting Sr=2000rpm, Sf=0.01mm/rev, Alon=7.02μm and Ator=9.29μm in LTC-RUAD. The delamination factor is only 0.054. The damage factors are reduced by 69.67% compared with CD.

Evaluation of Factors Affecting Delamination, Tensile Strength, Thrust Force and Surface Roughness in Drilling of GFRP

The drilling operation of glass fiber reinforced plastic (GFRP) composites has gained importance because they are used as structural components in many industries such as aerospace and aviation. In the drilling of GFRP composites, some problems such as deformation and fiber breakage occur. Thrust force, delamination, surface quality and cutting temperature are affected by drilling parameters and woven types in the drilling of GFRP composites. At the same time, delamination also affects tensile strength. In this study, the effects of drilling parameters and woven types of GFRP composites on thrust force, surface roughness, delamination factor, and cutting temperature were examined in the drilling of GFRP composites produced in unidirectional (UD), ± 45º and 0°/90º woven types. The effects of drilling parameters and the delamination factor on the tensile strength of the drilled specimen were also investigated. The result of this study indicated that thrust force, delamination factor, and surface roughness increased with increasing cutting speed and feed rate. An increase in feed rate decreased the cutting temperature while an increase in cutting speed increased the cutting temperature. Also, it was found that the delamination had a critical influence on the tensile strength of the GFRP composites.

Optimization for drilling process of metal-composite aeronautical structures

Metal-composite laminates and joints are applied in aircraft manufacturing and maintenance (repairing) using aluminum alloys (AA) and glass fiber-reinforced polymer (GFRP). In these applications, drilling has a prominent place due to its vast application in aeronautical structures’ mechanical joints. Thus, this study presents the influence of uncoated carbide drills (85C, 86C, H10N), cutting speeds (v c = 20, 40, and 60 m min−1), and feed rates (f = 0.05, 0.15, and 0.25 mm rev−1) on delamination factor, thrust force ( F t {F}_{\text{t}} ), and burr formation in dry drilling metal-composite laminates and joints (AA2024/GFRP/AA2024). Experiments were performed, analyzed, and optimized using the Box–Behnken statistical design. Microscopic digital images for delamination evaluation, piezoelectric dynamometer for thrust force acquisition, and burr analysis were considered. The major finding was that the thrust force during drilling depends significantly on the feed rate. Another significant factor was the influence of the drill type (combined or not with feed rate). In fact, it was verified that the feed rate and the drill type were the most significant parameters on the delamination factor, while the feed rate was the most relevant on thrust force. The cutting speed did not affect significantly thrust force and delamination factor at exit ( F da S ) \hspace{.25em}({F}_{{\text{da}}_{\text{S}}}) . However, the combination f × v c was significant in delamination factor at entrance ( F da E ) \text{ }({F}_{{\text{da}}_{\text{E}}}) . Based on the optimized input parameters, they presented lower values for delamination factors ( F da E = 1.18 {F}_{{\text{da}}_{\text{E}}}=1.18 and F da S = 1.33 {F}_{{\text{da}}_{\text{S}}}=\hspace{.25em}1.33 ) and thrust force ( F t = 67.3 N {F}_{\text{t}}=67.3\hspace{.5em}\text{N} ). These values were obtained by drilling the metal-composite laminates with 85C-tool, 0.05 mm rev−1 feed rate, and 20 m min−1 cutting speed. However, the burrs at the hole output of AA2024 were considered unsatisfactory for this specific condition, which implies additional investigation.