Drilling studies were conducted on glass/epoxy composite laminates having two different lay-ups [(0/90)4s and (0/ ± 45/90)2s]. Normal drills (2 flute with cone angle of 118°) made of high-speed steel (HSS), TiN-coated HSS, and TiC-coated HSS were used. Drilling parameters were optimized in terms of least thrust and torque. Parameters studied were thrust, torque, tool wear, form deviation, acoustic emission peak, and root mean square (RMS) of acoustic energy. It was observed that coated HSS drills perform little better than uncoated HSS for small number of holes, while their performance is inferior to uncoated HSS for larger number of holes. This is mainly due to peeling or chipping of the coating from base material (HSS). Also, the performance of TiN-coated HSS drill was observed to be better than TiC-coated HSS.

Ramalingam Krishnamurthy

Acoustic emissions

Coatings

Epoxy resins

Glass

Laminated composites

Steel

TITANIUM CARBIDE

Titanium nitride

Torque

ACOUSTIC EMISSION PEAK

Acoustic energy

chipping

HIGH SPEED STEEL DRILLS

ROOT MEAN SQUARE

Thrust

Tool wear

Drilling

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Studies on drilling of glass/epoxy laminates using coated high-speed steel drills

Materials and Manufacturing Processes

In this investigation, machining of composites, fabricated with randomly oriented chopped banana fiber of length 10 mm as reinforcement and hybrid polymer as matrix, is studied. Two hybrid polymers are used. One is made from 85% of isophthalic polyester and 15% of cashew nut shell liquid and the other is made from 85% of isophthalic polyester and 15% of cardanol. Conventional machining is carried out by taking three parameters (speed, feed and depth of cut) into consideration. Response surface methodology is used for design of experiments. Material removal rate (MRR) and surface roughness are investigated. © 2017 Elsevier Ltd.

Materials Today: Proceedings

Investigations on Machining of Banana Fibre Reinforced Hybrid Polymer Matrix Composite Materials

Face turning trials were carried out on glass fibre reinforced plastics (GFRP), carbon fibre reinforced plastics (CFRP) and kevlar fibre reinforced plastics (KFRP) cylindrical tubes to study their machined surfaces for possible application as friction surfaces. The surface roughness obtained and the observed morphology of the machined surfaces of fibre reinfoced plastics (FRP) composites are compared and are reported in this paper. The mechanisms of material removal and tool wear are also discussed and illustrated with scanning electron micrographs. The cutting forces encountered during machining of composites were also measured. © 1988.

Journal of Mechanical Working Technology

Machinability characteristics of fibre reinforced plastics composites

Composite Structures

Drilling of composite structures

Drilling of fibre reinforced plastics with conventional tools often results in defects like delamination, debonding, fibre pull-out, etc. Thrust is a major factor responsible for delamination and it mainly depends on tool geometry and feed rate. Trepanning tools, which were used in this study, were found to give reduced thrust while making holes on thin laminated composites. In this work the peculiarities of trepanning over drilling of unidirectional composites has been emphasised. The models for prediction of critical thrust and critical feed rate at the onset of delamination during trepanning of unidirectional composites based on fracture mechanics and plate theory also have been presented. Mathematical models correlating thrust and torque with tool diameter and feed rate have been developed through statistically designed experiments and effect of various parameters on them have been discussed. The critical feed rate is a function of strain energy release rate, elastic properties, sub-laminate thickness and diameter of the tool. It is observed that sub-laminate thickness is the most decisive parameter from the viewpoint of critical feed rates.

Composites Part A: Applied Science and Manufacturing

Trepanning on unidirectional composites: delamination studies

This paper presents the results of an experimental investigation into the effect of the geometry of a trepanning tool on thrust and torque during the drilling of uni-directional glass fibre-reinforced plastic (UD-GFRP) laminates. It is well-known that the most effective way of achieving good quality holes while drilling fibre-reinforced plastics (FRPs) is by reducing the thrust and torque. Therefore, this investigation was aimed at exploring the possibility of reducing the thrust and torque by using the concept of trepanning. The design considerations and development methodology of the trepanning tool are discussed. The appropriate tool geometry has been determined by using statistically planned experiments and analysis. Orthogonal arrays with analysis of means as well as analysis of variance have been used to assess individual factor and interaction effects and their significance levels. The investigations have revealed that the performance of the trepanning tool is superior to that of conventional twist drills in terms of thrust, torque and hole quality. Low production cost and ease of regrinding are its major additional advantages due to its simple geometry.

Journal of Materials Processing Technology

Investigations into the effect of geometry of a trepanning tool on thrust and torque during drilling of GFRP composites

Prediction of the location of delamination in the drilling of composite laminates

Journal	Materials and Manufacturing Processes
ISSN	10426914
Open Access	No