J. Paulo Davim

Experimental study of drilling glass fiber reinforced plastics (GFRP) manufactured by hand lay-up

Drilling is a frequently practiced machining process in industry due to the need for component assembly in mechanical pieces and structures. Drilling of composite materials is significantly affected by damage tendency of these materials under action of cutting forces (thrust force and torque). So the aim of this paper is the study of the cutting parameters (cutting velocity and feed rate) under specific cutting pressure, thrust force, damage and surface roughness in Glass Fiber Reinforced Plastics (GFRPs). A plan of experiments, based on the techniques of Taguchi, was established considering drilling with prefixed cutting parameters in a hand lay-up GFRP material. The analysis of variance (ANOVA) was performed to investigate the cutting characteristics of GFRPs using Cemented Carbide (K10) drills with appropriate geometries. The objective was to establish a correlation between cutting velocity and feed rate with the specific cutting pressure, thrust force, damage factor and surface roughness, in a GFRP material.

A note on the determination of optimal cutting conditions for surface finish obtained in turning using design of experiments

Abstract This paper presents a study of the influence of cutting conditions on the surface finish obtained by turning. A plan of experiments, based on the techniques of Taguchi, was designed and executed on controlled machining with cutting conditions prefixed in workpieces. Afterwards, the roughness was evaluated on workpieces using two different profilometers. The objective was to establish a correlation between cutting velocity, feed and depth of cut with the roughness evaluating parameters R a and R t , following the international norms. These correlations were obtained by multiple linear regression. Finally, confirmation tests were performed to make a comparison between the results predicted from the mentioned correlations and the theoretical results.

Drilling carbon fiber reinforced plastics manufactured by autoclave—experimental and statistical study

Drilling laminates composites materials are significantly affected by delamination tendency of these materials under action of cutting forces (thrust force and torque). On the other hand, drilling is an operation frequently used in industry due to the need for component assembly in mechanical pieces and structures. So the aim of this paper is the study of the cutting parameters (cutting velocity and feed rate) on power (Pc), specific cutting pressure (Ks), and delamination in carbon fiber reinforced plastics (CFRPs). A plan of experiments, based on the techniques of Taguchi, was established considering drilling with prefixed cutting parameters in an autoclave CFRP composite laminate. The analysis of variance was preformed to investigate the cutting characteristics of CFRPs using cemented carbide (K10) drills with appropriate geometries. The objective was to establish a correlation between cutting velocity and feed rate with the power (Pc) specific cutting pressure (Ks) and delamination factor (Fd) in a CFRP material. Finally, this correlation was obtained by multiple linear regression.

Design of optimisation of cutting parameters for turning metal matrix composites based on the orthogonal arrays

Abstract This paper presents a study of the influence of cutting conditions (cutting velocity and feed) and cutting time on turning metal matrix composites (MMCs). A plan of experiments, based on the techniques of Taguchi, was performed machining with cutting conditions prefixed in workpieces. An orthogonal array and the analysis of variance (ANOVA) are employed to investigate the cutting characteristics of MMC (A356/20/SiCp-T6) using PCD cutting tools. The objective was to establish a correlation between cutting velocity, feed and the cutting time with the tool wear, the power required to perform the machining operation and the surface roughness in workpiece. These correlations were obtained by multiple linear regression. Finally, confirmation tests were performed to make a comparison between the experimental results foreseen from the mentioned correlations.

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Diamond tool performance in machining metal–matrix composites

Abstract This paper presents an experimental machinability study of the metal–matrix composites (MMCs) A356/SiC/20p with brazed polycrystalline diamond (PCD) tools or chemical vapour deposition (CVD) diamond coated tools. The experimental procedure consisted of turning operations, during which cutting force, cutting tools flank wear and surface roughness obtained in composite workpiece were measured. The obtained results showed that PCD tools are important in cutting this composite type of reduced machinability. Actually, CVD diamond coated tools show short life, as tools wear evolution becomes very fast after coating rupture.

Effect of carbon fibre reinforcement in the frictional behaviour of Peek in a water lubricated environment

Abstract Owing to the potential use of poly-ether-ether-ketone (Peek) and 30% carbon fibre reinforced Peek (Peek-CF30) for orthopaedic application it was decided to investigate the effect of carbon fibre reinforcement and the meaning of different variables, such as counterface roughness, sliding velocity and contact stress on frictional behaviour. A pin-on-disc Plint TE67 connected to a computer was used to measure the friction evolution under dynamic contact stress and sliding speed conditions, applied according to a sinusoidal function. This sinusoidal model tries to reproduce the human walking conditions on the hip joint system. The treatment of experimental results was based on Taguchi’s techniques and on the analysis of variance (ANOVA). Scanning electron microscopy (SEM) analysis and energy dispersive spectroscopy (EDS) X-ray microanalysis were made in a post test examination.

Analysis on Drilling of Glass Fiber–Reinforced Polymer (GFRP) Composites Using Grey Relational Analysis

Glass fiber–reinforced polymer (GFRP) composite materials are an economic alternative to the engineering materials because of their superior properties. The present work focuses on the use of Grey relational analysis for optimizing the drilling parameters on the surface roughness and the thrust force in the drilling of GFRP composites. Taguchis L9, 3-level orthogonal array is used for the experimentation. Optimal machining parameters are determined by the Grey relational grade obtained from the Grey relational analysis for multiperformance characteristics. Experimental results show that the machining performance in the composite machining process can be improved at optimal drilling conditions.

Optimisation of cutting conditions in machining of aluminium matrix composites using a numerical and experimental model

Abstract In this paper, a methodology aiming at the selection of the optimised values for cutting conditions in machining processes, as turning and drilling aluminium matrix composites is proposed. An hybrid technique based on an evolutionary search over a design space obtained by experimental way is considered. The machining forces, the surface finish and the tool wear are experimentally measured considering the feed and the cutting velocity as predefined parameters. Using genetic algorithms for the optimal search of cutting conditions, the chromosomes represent cutting conditions defined according to a temporal scale and are composed by random keys. The merit functions are established based on multicriteria and evaluated using the experimental values obtained for the machining forces, the surface finish and the tool wear. The evolution of the solutions is based on an elitist strategy.

Analysis of Machinability During Hard Turning of Cold Work Tool Steel (Type: AISI D2)

Hard turning is an attractive replacement for grinding operations due to numerous advantages such as low capital investment, shorter setup time, higher material removal rate, better surface integrity, and elimination of cutting fluids. As a potential alternative process, there is a need to assess the machinability in high-precision and high-hardened components. The current study establishes the relationships between the cutting conditions (cutting speed, feed rate, and machining time) on machinability aspects (machining force, power, specific cutting force, surface roughness, and tool wear). The response surface methodology-based mathematical models are proposed for modeling and analyzing the effects of process parameters on machinability during turning of high chromium AISI D2 cold work tool steel using CC650WG wiper ceramic inserts. The experiments have been planned as per full factorial design. From the parametric analysis, it is revealed that the power increases with increase in feed rate, while the specific cutting force decreases, whereas the requirement of machining force is low at low values of feed rate and machining time. The response surface analysis also indicates that the surface roughness can be reduced at lower values of feed rate and machining time with higher values of cutting speed, while the maximum tool wear occurs at a cutting speed of 150 m/min for all values of feed rate.