THRUST FORCE AND TORQUE IN DRILLING THE NATURAL FIBER

D.Chandramohan et. al. / International Journal of Engineering Science and Technology Vol. 2(10), 2010, 6437-6451

THRUST FORCE AND TORQUE IN DRILLING THE NATURAL FIBER

REINFORCED POLYMER COMPOSITE MATERIALS AND EVALUATION OF

DELAMINATION FACTOR FOR BONE GRAFT SUBSTITUTES

-A WORK OF FICTION APPROACH

Mr. D. CHANDRAMOHAN*

Ph.D.,Research Scholar, Department of Mechanical Engineering, Anna University of Technology, Coimbatore Coimbatore, Tamilnadu, India

Dr.K.MARIMUTHU#

Associate Professor, Department of Mechanical Engineering, Anna University of Technology- Coimbatore Coimbatore, Tamilnadu, India

Abstract This paper discusses about the Natural Fiber Reinforced Composite Materials contribution as bone implants. Biomaterial science is an interdisciplinary field that represents one of the most sophisticated trends in worldwide medical practice. In the last decades, researchers have developed new materials to improve the quality of human life. Owing to the frequent occurrence of bone fractures, it is important to develop a plate material for fixation on the fractured bone. These plate materials have to be lightweight, allow stiffness, and be biocompatible with humans. Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials, owing to the need for joining fractured bone by means of plate material in the field of orthopedics. An effort to utilize the advantages offered by renewable resources for the development of biocomposite materials based on biopolymers and natural fibers has been made through fabrication of Natural fiber powdered material (Sisal (Agave sisalana), Banana (Musa sepientum), and Roselle (Hibiscus sabdariffa)) reinforced polymer composite plate material by using bio epoxy resin Grade 3554A and Hardner 3554B. Instead of orthopedics alloys such as Titanium, Cobalt chrome, Stainless steel, and Zirconium, this plate material can be used for internal fixationand aso external fixation on human body for fractured bone. The present work focuses on the prediction of thrust force and torque of the natural fiber reinforced polymer composite materials, and the values, compared with the Regression model and the Scheme of Delamination factor / zone using machine vision system, also discussed with the help of Scanning Electron Microscope [SEM]. Key words: Natural fibers, Bio epoxy resin, Thrust force, Torque, Regression Model, Delamination, SEM. 1. Introduction A judicious combination of two or more materials produces a synergistic effect. Composites are materials, usually man-made, which are a three-dimensional combination of at least two chemically distinct materials, with a distinct interface separating the components, created to obtain properties that cannot be achieved by any of the components acting alone. Composites are a combination of two materials in which one of the materials, called the reinforcing phase, is in the form of fibers, sheets, or particles, and is embedded in the other material called the matrix phase. The reinforcing material and the matrix material can be metal, ceramic, or polymer. Typically, reinforcing materials are strong with low densities, while the matrix is usually a ductile, or tough, material. If the composite is designed and fabricated correctly, it combines the strength of the reinforcement with the toughness of the matrix to achieve a

ISSN: 0975-5462 6437


combination of desirable properties not obtainable in any single conventional material. The downside is that such composites are often more expensive than conventional materials. Examples of some current application of composites include common replacement materials used for fixation, such as Titanium, Cobalt chrome, Zirconium, and Stainless steel. The selection of the material for implants depends on the type of stress and patients’ needs. Factors such as biocompatibility and high modulus of elasticity of the material make it difficult for the grafts to work properly when they are implanted in humans. This characteristic feature gives birth to an increasing number of studies by researchers in materials that can be used as the grafting material. Currently, the artificial grafts that meet all the requirements of the orthopedic surgeons are not good enough, and hence, this field can be explored further by the researchers. This paper has proposed suggestions for using natural fiber reinforced composite as a plate material, which uses pure natural fibers that are rich in medicinal properties, such as Sisal, Banana, and Roselle (hybrid) fiber. In this study, rather than using pure biomaterial as reinforcement with polymer composite, coating over the plate material is also done by using highly biocompatible materials, such as calcium phosphate, calcium sulfate, hen eggshell powdered material, and Hydroxy Apatite (hybrid) composite. This plate material can be used as an inside fixation over the fractured bone. The most important point that the researchers have to take into account is that these steps taken will help mankind to develop and have a more pleasant life.

2. Background

Biomaterials improve the quality of life of an ever increasing number of people every year. The range of applications is vast and includes joint and limb replacements, artificial arteries and skin, contact lenses, and dentures. This increasing demand arises from an aging population with higher quality of life expectations. The biomaterials community is producing new and improved implant materials and techniques to meet this demand, and is also assisting in the treatment of younger patients where the necessary properties are even more demanding. A counterforce to this technological push is the increasing level of regulation and the threat of litigation. To meet these conflicting needs, it is necessary to have reliable methods of characterization of the material and material/host tissue interactions. The main property required for a biomaterial is that it should not illicit an adverse reaction when placed into service [2]. The various materials used in biomedical applications can be grouped into (a) metals, (b) ceramics, (c) polymers, and (d) composites made from the above-mentioned grouping. Metals and alloys employed successfully as biomaterials include gold, tantalum, stainless steel, NiTi (Shape memory alloy), Co-Cr, and Ti alloys. Machining of such orthopedic alloy implants with high-speed machining can offer advantages, but may also present some disadvantages including complexity and high machining cost. During the past decades, titanium was used for bone replacements; however, these implants were simple geometric approximations of the bone shape. Thus, mismatches could occur between the real bone and implants, often causing stress concentrations and premature implant failure. The machining stocks were uneven and more than the required levels. This led to more weight at rough casting stage and resulted in increased machining time. Furthermore, these castings were manufactured in green sand molding process, which led to poor surface finish, more material in machining surfaces, and less dimensional stability. The above-mentioned complexities gave way for the next-generation bone implants, namely, polymers and ceramics, which have better biocompatibility and good tensile properties.

3. Objectives of the Study

An effort to utilize the advantages offered by renewable resources for the development of biocomposite materials based on biopolymers and natural fibers. Fabrication of natural fiber (Sisal, Banana, and Roselle (hybrid) composite fiber) reinforced polymer (NFRP) composite plate material by using bio epoxy resin, instead of orthopedic alloys, such as Titanium, Cobalt chrome, Stainless steel, and Zirconium. It is yet another object of the present invention that the prediction of the thrust force and torque of the natural fiber reinforced polymer composite materials are calculated and their values are compared with the regression model and the scheme of delamination factor / zone using machine vision system. It is yet another object of the present invention that the natural fiber reinforced polymer composite material coated by calcium phosphate and hydroxyapatite (hybrid) composite can be used for both internal and external fixation on the human body for fractured bone. 4. Natural Fibers Natural fibers present important advantages such as low density, appropriate stiffness and mechanical

ISSN: 0975-5462 6438


properties and high disposability and renewability. Moreover, they are recyclable and biodegradable. Over the last decade, composites of polymers reinforced by natural fibers have received increased attention. Natural fibers such as Sisal, Banana & Roselle fibers possess good reinforcing capability when properly compounded with polymers. One of the unique aspects of designing parts with fiber reinforced composite materials is that the mechanical properties of the material can be tailored to fit a certain application. In this research, fibers used as powdered materials as shown in SEM images (Fig 4.1, 4.2 & 4.3).

Fig.4.1. SEM Particle Size of Fig.4.2. SEM Particle Size of Fig 4.3.SEM Particle size of Sisal and Banana (hybrid) Roselle and Banana (hybrid) Roselle and Sisal (hybrid)

5. Composite preparation Materials Used The specimen used in this study is a plate of 60x40 mm made of natural fiber reinforced composite material. The composite is made of natural fibers. Commercially available natural fibers are taken. The materials used in this project are (as shown in fig 5.1 Specimens arranged in Left to Right 1, 2, 3,4,5,6 listed below)

1. Banana fibre reinforced composite 2. Sisal fibre reinforced composite 3. Roselle fibre reinforced composite 4. Sisal & Roselle (hybrid) fibre reinforced composite 5. Banana & Sisal (hybrid) fibre reinforced composite 6. Banana & Roselle (hybrid) fibre reinforced composite

Fig 5.1 Specimens (60x40 mm)

5.1 Chemical Treatment The fibers were cleaned normally in clean running water and dried. A glass beaker was taken and a solution comprising 6% NaOH and 80% distilled water was prepared. After adequate drying of the fibers in normal shading for 2–3 hours, the fibers were taken and soaked in the prepared NaOH solution. Soaking was carried out at different time intervals depending on the required strength of the fiber. For our study, the fibers were soaked in the solution for 3 hours. After completing the soaking process, the fibers were taken out and washed in running water and dried for another 2 hours. Subsequently, the fibers were taken for the next fabrication process, namely the procasting process. 5.2 Advantages of chemical treatment Chemical treatment with NaOH removes the moisture content from the fibers, thereby increasing its strength. Chemical treatment also enhances the flexural rigidity of the fibers. This treatment clears all the impurities in the fiber material and also stabilizes the molecular orientation.

ISSN: 0975-5462 6439


5.3 Manufacturing process A mold of 60-mm length and 40-mm diameter was created using GI sheet mold. An OHP Sheet was taken and a releasing agent was applied over it and fitted with the inner side of the mold and allowed to dry. A glass beaker and a glass rod or a stirrer were taken and cleaned well with running water and subsequently with warm water. Then, calculated quantity of bio epoxy resin Grade 3554A and Hardner 3554B Resin was added and the mixture was stirred for nearly 15 min. Stirring was done to create a homogeneous mixture of resin and accelerator molecules. Subsequently, calculated quantity of fibers was added and the stirring process was continued for the next 45 min. Then, the mixture was poured into the mold and rammed mildly for uniform settlement. The mold was allowed to solidify for nearly 24 hours. 6. Experimental setup A number of drilling experiments were carried out on a CNC machining center (Maxmill) using HSS twist drills for the machining of NFRP composites. A two-component drill tool dynamometer was used to record the thrust force and torque. Conventional high-speed steel twist drills were used as much as cemented tungsten carbide drills. Tool geometry is a relevant aspect to be considered in drilling of fiber-reinforced plastics, particularly when the quality of the machined hole is critical. Factorial Design A 33 full factorial design with a total of 27 experimental runs were carried out. The thrust force and torque were the response variables recorded for each run. The effect of the machining parameters is another important aspect to be considered. It can be observed that the cutting speeds from 20 to 60 m/min are usually employed, whereas feed rate values lower than 0.3 mm/rev are frequent. Cutting speed is not a limiting factor when drilling polymeric composites, particularly with hard metals, and therefore, the use of cutting speeds below 60 m/min may be explained by the maximum rotational speed of conventional machining tools, because drill diameters above 10 mm are rarely reported. Another reason for keeping cutting speeds below 60 m/min may reside in the fact that higher cutting values lead to higher cutting temperature, which in turn may cause the softening of the matrix. The use of feed rates below 0.3 mm/rev may be associated to the delamination damage caused when this parameter is increased. Table shows the detail of variables used in the experiment.

Table 6.1 Assignment of the levels to the factors

Level Drill size,d

(mm) Revolution ,N (rpm)

Feed rate,f (mm/rev)

1 3 600 0.1

2 4 900 0.2

3 5 1200 0.3

ISSN: 0975-5462 6440


Table 6.2 Comparison results of Sisal & Roselle Thrust force and Torque

Sl. No.

Drill dia Speed Feed Thrust Torque (RM) (RM)

(mm) (rpm) (mm/rev) (N) (N-m) Thrust Torque

(N) (N-m)

1 3 300 0.1 3 0.93 3.105598 0.936865

2 3 600 0.1 3.86 0.96 4.003891 0.968111

3 3 900 0.1 4.48 0.98 4.645422 0.98687

4 3 300 0.2 4.86 1.72 5.036403 1.725326

5 3 600 0.2 6.27 1.77 6.493179 1.782869

6 3 900 0.2 7.27 1.81 7.533562 1.817415

7 3 300 0.3 6.45 2.45 6.682641 2.466038

8 3 600 0.3 8.31 2.54 8.61559 2.548286

9 3 900 0.3 9.65 2.59 9.99604 2.597663

10 4 300 0.1 5.04 1.2 5.226974 1.204046

11 4 600 0.1 6.5 1.24 6.738873 1.244204

12 4 900 0.1 7.54 1.26 7.818622 1.268312

13 4 300 0.2 8.18 2.21 8.476675 2.217366

14 4 600 0.2 10.55 2.28 10.92855 2.291319

15 4 900 0.2 12.23 2.32 12.6796 2.335718

16 4 300 0.3 10.85 3.15 11.24743 3.169319

17 4 600 0.3 13.99 3.26 14.50074 3.275022

18 4 900 0.3 16.23 3.32 16.82415 3.338482

19 5 300 0.1 7.55 1.46 7.827643 1.462729

20 5 600 0.1 9.74 1.5 10.09178 1.511514

21 5 900 0.1 11.3 1.53 11.70876 1.540802

22 5 300 0.2 12.25 2.68 12.69423 2.693755

23 5 600 0.2 15.79 2.77 16.36602 2.783597

24 5 900 0.2 18.32 2.82 18.9883 2.837534

25 5 300 0.3 16.25 3.83 16.84356 3.85023

26 5 600 0.3 20.95 3.96 21.71555 3.978644

27 5 900 0.3 24.31 4.04 25.19496 4.055737 Where, RM-Regression Model

ISSN: 0975-5462 6441


Table 6.3 Comparison results of Sisal & Banana Thrust force and Torque

Sl. No. Drill dia Speed Feed Thrust Torque (RM) (RM)

(mm) (rpm) (mm/rev) (N) (N-m) Thrust Torque (N) (N-m)

1 3 300 0.1 6.93 0.85 6.95012 0.87763

2 3 600 0.1 9.27 0.82 9.29083 0.84693

3 3 900 0.1 10.98 0.8 11.0102 0.82946

4 3 300 0.2 17.99 1.56 18.0399 1.60562

5 3 600 0.2 24.05 1.5 24.1154 1.54944

6 3 900 0.2 28.5 1.47 28.5783 1.5175

7 3 300 0.3 31.43 2.22 31.5172 2.2861

8 3 600 0.3 42.02 2.14 42.1318 2.20612

9 3 900 0.3 49.79 2.09 49.9289 2.16063

10 4 300 0.1 8.38 1.1 8.40218 1.13844

11 4 600 0.1 11.2 1.06 11.2319 1.09861

12 4 900 0.1 13.27 1.04 13.3105 1.07596

13 4 300 0.2 21.75 2.02 21.8088 2.08277

14 4 600 0.2 29.07 1.95 29.1538 2.0099

15 4 900 0.2 34.45 1.91 34.549 1.96846

16 4 300 0.3 38 2.87 38.102 2.96548

17 4 600 0.3 50.8 2.77 50.9342 2.86173

18 4 900 0.3 60.2 2.72 60.3603 2.80272

19 5 300 0.1 9.71 1.35 9.73433 1.39303

20 5 600 0.1 12.98 1.3 13.0127 1.34429

21 5 900 0.1 15.38 1.28 15.4209 1.31658

22 5 300 0.2 25.2 2.47 25.2666 2.54854

23 5 600 0.2 33.68 2.38 33.776 2.45937

24 5 900 0.2 39.92 2.33 40.0267 2.40866

25 5 300 0.3 44.02 3.52 44.143 3.62864

26 5 600 0.3 58.85 3.39 59.0097 3.50169

27 5 900 0.3 69.74 3.32 69.9303 3.42949

ISSN: 0975-5462 6442


Table 6.4 Comparison results of Roselle & Banana Thrust force and Torque

Sl. No. Drill dia Speed Feed Thrust Torque (RM) (RM)

(mm) (rpm) (mm/rev) (N) (N-m) Thrust Torque (N) (N-m)

1 3 300 0.1 6.93 0.85 6.95012 0.87763

2 3 600 0.1 9.27 0.82 9.29083 0.84693

3 3 900 0.1 10.98 0.8 11.0102 0.82946

4 3 300 0.2 17.99 1.56 18.0399 1.60562

5 3 600 0.2 24.05 1.5 24.1154 1.54944

6 3 900 0.2 28.5 1.47 28.5783 1.5175

7 3 300 0.3 31.43 2.22 31.5172 2.2861

8 3 600 0.3 42.02 2.14 42.1318 2.20612

9 3 900 0.3 49.79 2.09 49.9289 2.16063

10 4 300 0.1 8.38 1.1 8.40218 1.13844

11 4 600 0.1 11.2 1.06 11.2319 1.09861

12 4 900 0.1 13.27 1.04 13.3105 1.07596

13 4 300 0.2 21.75 2.02 21.8088 2.08277

14 4 600 0.2 29.07 1.95 29.1538 2.0099

15 4 900 0.2 34.45 1.91 34.549 1.96846

16 4 300 0.3 38 2.87 38.102 2.96548

17 4 600 0.3 50.8 2.77 50.9342 2.86173

18 4 900 0.3 60.2 2.72 60.3603 2.80272

19 5 300 0.1 9.71 1.35 9.73433 1.39303

20 5 600 0.1 12.98 1.3 13.0127 1.34429

21 5 900 0.1 15.38 1.28 15.4209 1.31658

22 5 300 0.2 25.2 2.47 25.2666 2.54854

23 5 600 0.2 33.68 2.38 33.776 2.45937

24 5 900 0.2 39.92 2.33 40.0267 2.40866

25 5 300 0.3 44.02 3.52 44.143 3.62864

26 5 600 0.3 58.85 3.39 59.0097 3.50169

27 5 900 0.3 69.74 3.32 69.9303 3.42949 7. Prediction techniques 7.1 Regression model The statistical tool, regression analysis, helps to estimate the value of one variable from the given value of another. In regression analysis, there are two types of variables. The variable whose value is influenced or is to be predicted is called dependent variable, and the variable that influences the values or used for prediction is called independent variables. The tool, regression analysis, can be extended to three or more variables. If two variables are taken into account, then it is called simple regression. The tool of regression when extended to three or more variables is called multiple regressions. 7.2 SPSS SPSS (originally, Statistical Package for the Social Sciences) was released in its first version in 1968. SPSS is among the most widely used programs for statistical analysis in social science. It is used by market researchers, health researchers, survey companies, government, education researchers, marketing organizations, and others. In

ISSN: 0975-5462 6443


addition to statistical analysis, data management (case selection, file reshaping, creating derived data) and data documentation (a metadata dictionary is stored with the data) are the features of the base software. Statistics included in the base software are: Descriptive statistics: Cross tabulation, Frequencies, Descriptives, Explore. Descriptive Ratio Statistics Bivariate statistics: Means, t-test, ANOVA, Correlation (bivariate, partial, distances), Nonparametric tests Prediction for numerical outcomes: Linear regression Prediction for identifying groups: Factor analysis and cluster analysis (two-step, K means, hierarchical). Discriminant Statistical output is to a proprietary file format (*.spo file, supporting pivot tables), for which, in addition to the in-package viewer, a standalone reader is provided. The proprietary output can be exported to text or Microsoft Word. Alternatively, output can be captured. as data (using the OMS command), text, tab-delimited text, HTML, XML, SPSS dataset, or a variety of graphic image formats (JPEG, PNG, BMP, and EMF). 7.2.2 Regression equations: Thrust = k * d a * n b * f c ------------ (7.1) Torque = k * d a * n b * f c ------------ (7.2) Where d = Drill diameter in mm n = Speed in rpm f = Feed rate in mm/rev a, b & c = Regression constants

Table 7.1 Regression equations for thrust force

Material Thrust force R2

Sisal 1.479916792 X d ^ 1.695179761 X n ^ 0.218422665 X f ^ 0.927436761 0.93614

Banana 3.072028878 X d ^ 1.347046253 X n ^ 0.233186110 X f ^ 0.886143709

0.89341

Roselle 3.023946833 X d ^ 1.094546824 X n ^ 0 .324203073 X f ^ 0.951921753

0.88378

Sisal and Roselle(Hybrid)

3.0283346946 X d ^ 1.809727356 X n ^ 0.366531308 X f ^ 0.697522528

0.91185

Sisal and Banana (Hybrid)

7.346100813X d ^ 0.659519445 X n ^ 0.418769028X f ^ 1.376076865

0.95432

Banana and Roselle(Hybrid)

7.34610183X d ^ 0.266522184 X n ^ 0. 522769028X f ^ 1. 768086565

0.95745

Table 7.2 Regression equations for torque

Material Thrust force R2

Sisal 2.849305728 X d ^ 1.099468559 X n ^ -.066603083 X f ^ 0.962428131 0.87688

Banana 2.187147307 X d ^ 1.138389699 X n ^ -.037946866 X f ^ 1.061918604 0.88161

Roselle 1.534106581 X d ^ 1.348045235 X n ^ -.09453993 X f ^ 0.772847627 0.88963

Sisal and Roselle(Hybrid)

2.085745348 X d ^ .872156974 X n ^ .047331957 X f ^ 0.880955972

0.88741

Sisal and Banana (Hybrid)

3.239667434 X d ^ 0.90444033 X n ^ -0.051380071 X f ^ 0.871441681

0.867421

Banana and Roselle(Hybrid)

3.239667434 X d ^ 0.90444033 X n ^ -0.051380071 X f ^ 0.871441681

0.81094

ISSN: 0975-5462 6444


8. DELAMINATION The advantage of the composite materials over conventional materials is that they possess high specific strength, stiffness, and fatigue characteristics, which enable structural design to be more versatile. Owing to the inhomogeneous and anisotropy nature of composite materials, their machining behavior differs in many respects from metal machining. In recent years, customer requirements have put greater emphasis on product development, with new challenges to manufacturers, such as machining techniques. Machining of composite materials requires the need for better understanding of cutting process with regard to accuracy and efficiency. Though near net shape process have gained a lot of attention, more intricate products need secondary machining to achieve the required accuracy. Drilling is the most frequently used secondary operation for fiber-reinforced materials. Induced delamination occurs both at the entry and exit planes of the work piece. These delaminations could be correlated to the thrust force during the approach and exit of the drill. Delamination is one of the major concerns in drilling holes in composite materials. To understand the effects of the process parameters on delamination, numerous experiments have to be performed and analyzed mathematical models have to be built on the same. Modeling of the formation of delamination is highly complex and expensive. Hence, statistical approaches are widely used over the conventional mathematical models. Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials owing to the need for joining fractured bone by means of plate material in the field of orthopedics, as shown in Figure 8.1.

Fig 8.1 Internal Plate Fixation In Humerus Bone

8.1Types of Delamination 8.2 Peel-up Delamination Peel-up occurs at the entrance plane of the work piece. This can be explained as follows. After cutting, the edge of the drill makes contact with the laminate, and the cutting force acting in the perpendicular direction is the driving force for delamination. It generates a peeling force in the axial direction through the slope of the drill flute, which results in separating the laminas from each other forming a delamination zone at the top surface of the laminate, which mainly depends on speed and point angle.

Fig 8.2 Peel up delamination

ISSN: 0975-5462 6445


8.3 Push-down Delamination Push out is the delamination mechanism occurring as the drill reaches the exit side of the material and can be explained as follows. As the drill approaches the end, thickness of the uncut chip gets smaller and resistance to deformation decreases. At some point, the thrust force exceeds the interlaminar bond strength and delamination occurs. This happens before the laminate is completely penetrated by the drill, and mainly depends on the feed rate and drill diameter. 8.5. Procedure to calculate the value of delamination factor: Drilling was done in the CNC MAXMILL for three different drill diameters of 3, 4, and 5 mm, respectively. Then, the job was placed in the MACHINE VISION system to capture the digital image of the hole drilled. This was done by using different zoom factors (11x, 67x, 22x, 134x).

Fig 8.3 Push down delamination

8.5. Procedure to calculate the value of delamination factor: Drilling is done in the CNC MAXMILL for three different drill diameters of 3mm, 4mm, and 5mm respectively. Then the job is placed in the MACHINE VISION system to capture the digital image of the hole drilled. This is done by using various zoom factors (11x, 67x, 22x, 134x). A circle was drawn using the draw tool available in the RAPID-I software for both maximum diameter and nominal diameter. From the values of Dmax and Dnom, delamination factor was calculated using the following formula: (Fd ) = Dmax/Dnom ----- (8.1)

The first part of the equation represents the size of the crack contribution and the second part represents the damage area contribution. Fda = α (Dmax / Dnom) + β (Amax / Anom) ----- (8.2) Where, Amax – Maximum area related to the maximum diameter of the delamination zone. Anom – Area of the nominal hole. In this work, α = (1- β), ----- (8.3) β = Amax / (Amax - Anom). ----- (8.4) Fda = (1- β)*Fd + ((Amax / (Amax - Anom)*(Fd

2- Fd)). ----- (8.5) 8.5.1 Calculations Delamination factors, Delamination factor (Fd ) = Dmax/Dnom ----- (8.6)

Where, Dmax – Maximum diameter corresponding to the Delamination zone.

ISSN: 0975-5462 6446


Dnom – Nominal diameter.

Adjusted Delamination factor (Fda) = Fd + {(Ad/ (Amax-Ao)) ( Fd2- Fd)} -----(8.7)

Where, Fda – Adjusted Delamination factor. Fd – Delamination factor. Ad – Area of the Delamination zone. Ao – Nominal area. 8.6 Scheme of Delamination factor / zone using machine vision system Fig 8.6.1 Delamination zone Fig 8.6.2Delamination zone Fig 8.6.3 Delamination zone (for Roselle & Banana 5 mm dia) (for Roselle & Sisal 5 mm dia) (for Sisal &Banana 5 mm dia)

Table 8.1 Delamination Factor (Roselle and Banana) for d=5mm

S.NO FEED SPEED DELAMINATON FACTOR

(mm/rev) ( rpm ) Fd Fda

1 0.1 600 1.205 1.99851

2 0.1 900 1.2034 1.99433

3 0.1 1200 1.2022 1.99199

4 0.2 600 1.176 1.92342

5 0.2 900 1.17 1.90807

6 0.2 1200 10162 1.88771

7 0.3 600 1.098 1.72896

8 0.3 900 1.092 1.71445

9 0.3 1200 1.084 1.69521

ISSN: 0975-5462 6447


Table 8.2 Delamination Factor (Roselle and Sisal) for d=5mm



1 0.1 600 1.21 2.01161

2 0.1 900 1.209 2.00899

3 0.1 1200 1.206 2.00113

4 0.2 600 1.196 1.97504

5 0.2 900 1.92 1.96466

6 0.2 1200 1.184 1.94398

7 0.3 600 1.148 1.85235

8 0.3 900 1.142 1.83731

9 0.3 1200 1.134 1.81735

Table 8.3 Delamination Factor (Sisal and Banana) for d=5mm



1 0.1 600 1.193 1.96725

2 0.1 900 1.189 1.95689

3 0.1 1200 1.1804 1.93471

4 0.2 600 1.156 1.87251

5 0.2 900 1.15 1.85738

6 0.2 1200 1.142 1.83731

7 0.3 600 1.078 1.68085

8 0.3 900 1.073 1.66894

9 0.3 1200 1.065 1.64996 9. SCANNING ELECTRON MICROSCOPE 9.1 Introduction The Scanning Electron Microscope (SEM) is a type of Electron microscope that images the sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. The electrons interact with the atoms that make up the sample producing signals that contain information about the samples surface topography, composition and other properties such as electrical conductivity. SEM can produce very high-resolution images of a sample surface, revealing details about less than 2 to 5 nm in size. Due to the very narrow electron beam, SEM micrographs have a large depth of fielding a characteristic three-dimensional appearance useful for understanding the surface of a structure of a sample. For conventional imaging in the SEM, specimens must be electrically conductive, at least at the surface, and electrically grounded to prevent the accumulation of electrostatic charge at the surface. Metal objects require little special preparation for SEM except for cleaning and mounting on a specimen stub.

ISSN: 0975-5462 6448


Nonconductive specimens tend to charge when scanned by the electron beam, and especially in secondary electron imaging mode, this causes scanning faults and other image artifacts. They are therefore usually coated with an ultrathin coating of electricially conducting material, commonly gold, deposited on the sample either by low vacuum sputter coating or by high vacuum evaporation. Conductive materials in current use for specimen coating include gold, gold/palladium alloy, platinum, osmium, iridium, tungsten, chromium and graphite. Coating prevents the accumulation of static electric charge on the specimen during electron irradiation. The image may be captured by photography from a high resolution cathode ray tube, but in modern machines is digitally captured and displayed on a computer monitor and saved to a computers hard disc. All samples must also be of an appropriate size to fit in the specimen chamber and are generally mounted rigidly on a specimen holder called a specimen stub. Several models of SEM can examine any part of a 6-inch (25cm) semiconductor wafer, and some can tilt an object of that size to 45°. Fig 9.1 SEM of Fig 9.2 SEM of Fig 9.3 SEM of Sisal and banana(hybrid) Roselle and banana(hybrid) Roselle and sisal (hybrid)

CONCLUSION Based on the experimental results obtained, the following conclusions can be extracted: Effect Of Thrust Force In general, the thrust and torque parameters will mainly depend on the manufacturing conditions employed, such as feed, cutting speed, tool geometry, machine tool, and cutting tool rigidity. A larger thrust force occurs for larger diameter drills and higher feed rates. In other words, feed rate and drill diameter are recognized as the most significant factors affecting the thrust force. Worn-out drill may be one of the major reasons for the drastic increase in the thrust force as well as for the appearance of larger thrust forces when using multifacet drill than those when using twist drill at high cutting speed. Although tools are worn out quickly and the thrust force increases drastically as cutting speed increases, an acceptable hole entry and exit is maintained. We found that the thrust force is drastically reduced when the hole is predrilled to 0.4 mm or above. The thrust force increases with the increase in fiber volume fraction. Although it is known that the thrust force increases with the increase in the feed, this study provided quantitative measurements of such relationships for the present composite materials. In general, increasing the cutting speed will decrease the thrust force. This work has shown that the cutting speed has an insignificant effect on the thrust force when drilling at low feed values. At high feed values, the thrust force decreases with an increased cutting speed. Effect Of Torque It can be observed that thrust force and torque increase with the drill diameter and feed rate. By examining these results, it can be concluded that the torque slightly increases as the cutting speed increases. However, we found that the increase in torque was much smaller than that in thrust force, with the increasing cutting speed. The average torque appearing when using a multifacet drill was larger than that using the twist drill at low drilling speed, and the average torque when using a multifacet drill was smaller than that when using twist drill at high drilling speed. It was noticed that the average torque decreased as the drilled length increased for twist drill. Furthermore, the effect of feed, speed, and fiber volume fraction on the resulting torque in drilling the specimen was also observed. The results indicate that the torque increases as the feed increases. This increase is owing to the increasing cross-sectional area of the undeformed chip. The results also indicate that the torque increases with the increase in the fiber volume fraction. Increasing fiber volume fraction increases the static strength, and thus, the resistance of the composite to mechanical drilling increases. This leads to the increase in the required thrust force and torque. The

ISSN: 0975-5462 6449


result also indicates that the torque decreases when increasing the cutting speed. Finally this study observed that one of the best materials is Sisal and Roselle (Hybrid), which can be used for internal fixation, when compared with other materials. The reason could be the reduced fiber bridging effect resulting in lower fiber pull in/pull out during drilling process, which are observed in delamination factors and delamination zone. The complete breaking of the fiber rather than pull out was observed through Scanning Electron Microscope (SEM) analysis. In future, this plate material can be externally coated with calcium phosphate, hen eggshell powdered material, and Hydroxy Apatite (hybrid) composite. Furthermore, this plate material can be used for internal fixation and also external fixation in fractured bones in human body. The most important point that researchers have to have in mind is that these steps taken will help humans to develop and have a more pleasant life. Acknowledgement

We express our sincere thanks to my beloved parents for their invaluable love; moral support and constant encouragement in my life.We owe immense gratitude to our principal Prof.Dr.V.Selladurai,Ph.D., Coimbatore Institute of Technology, Coimbatore for his moral support during the course of my Research work. We sincere thanks to Prof.Dr.G.Sundararaj,Ph.D., Professor, Department of Production Engineering, P.S.G.College of Technology, Coimbatore and Prof.Dr.I.Rajendran,Ph.D., Professor and Head, Department of Mechanical Engineering, Dr.Mahalingam College of Engineering &Technology, Coimbatore for their valuable guidance and suggestions.

This research was sponsored by the INSTITUTION OF ENGINEERS (INDIA), KOLKATA. We wish to acknowledge their support.

We would like to acknowledge THE CONTROLLER OF PATENTS & DESIGNS, The Patent office, Chennai, INDIA for filed this research work provisional specification [PATENT APPLICATION NO.2349/CHE//2010].

We would also like to acknowledge Dr.L.Karunamoorthy, Ph.D., Professor and Head of Central Workshop at the ANNA UNIVERSITY, CHENNAI for his help in SEM and EDX Analysis.

We would like to thank the Reviewers of this editorial system for their valuable inputs and comments.

REFERENCES

[1] A.M. Abrao, P.E. Faria, J.C. Campos Rubio, P. Reis and J. Paulo Davim (2006) ‘Drilling of fiber reinforced plastics: A review’ Elsevier - Journal of Materials Processing Technology 186 (2007) 1–7 [2] M.M. Bain, Eggshell strength: a mechanical/ultrastrucutral evaluation. Ph. D. Thesis, University of Glasgow, Scotland (1992). [3] Cornell CN, Lane JM, Chapman M, Merkow R, Seligson D, Henry S, et al. Multicenter trial of collagraft as bone graft Substitute. J Orthop Trauma 1991; 5:1–8. [4] Craig M. Clemons and Daniel F. Caulfield (1994) ‘Natural fibers’ Sage Journals – Journal of Reinforced Plastics Composites - 1354-66 [5] U.A. Khashaba, M.A. Seif and M.A. Elhamid (2006) ‘Drilling analysis of chopped composites’ Elsevier - Composites: Part A 38 (2007) 61–70 [6] S.C. Lin and IK. Chen (2005) ‘Drilling carbon fiber-reinforced composite material at high speed’ Composite Structures 71 (2005) 407–413 [7] Marta Fernandes and Chris Cook (2006) ‘Drilling of carbon composites using a one shot drill bit - Part II: empirical modeling of maximum thrust force’ Elsevier - International Journal of Machine Tools & Manufacture 46 (2006) 76–79 [8] N.S. Mohan, A. Ramachandra and S.M. Kulkarni (2005) ‘Influence of process parameters on cutting force and torque during drilling of glass–fiber polyester reinforced composites’ Elsevier - Composite Structures 71 (2005) 407–413 [9] Mohanty AK, Misra M, Hinrichsen G. Biofibres, biodegradable polymers and biocomposites: An overview. Macromol Mater Eng 2000; 276/277:1–24 [11] R. Murugan, S. Rama Krishna- Composite science and technology (Division of bioengineering), Faculty of bioengineering, National university of Singapore [12] K. Palanikumar and J. Paulo Davim (2006) ‘Mathematical model to predict tool wear on the machining of glass fibre reinforced plastic composites’ Elsevier - Materials and Design 28 (2007) 2008–2014 [13] S. Panthapulakkal, A. Zereshkian and M. Sain (2006) ‘Preparation and characterization of wheat straw fibers for reinforcing application in injection molded thermoplastic composites’ Elsevier - Bioresource Technology Volume 97, Issue 2, January 2006, Pages 265-272 [14] Paul Wambua*, Jan Ivens, Ignaas Verpoest (2003) ‘Natural fibres: can they replace glass in fibre reinforced plastics?’ Elsevier - Composites Science and Technology 63 (2003) 1259–1264 [15] Ramakrishna S, Mayer J, winter mantel E, Leong KW. Biomedical Applications of polymer-composite materials: a review.Comp Sci Tech 2001; 61:1189–224. [16] C.C. Tsao and H. Hocheng (2007) ‘Evaluation of Thrust Force and Surface Roughness in Drilling Composite Material Using Taguchi Analysis and Neural Network’ Elsevier - Journal of Materials Processing Technology, [17] M. Zampaloni, F. Pourboghrat, S.A. Yankovich (2007) ‘Kenaf natural fiber - A discussion on manufacturing problems and solutions’ Composites Part A: Volume 38, Issue 6 June 2007, Pages 1569-1580.

ISSN: 0975-5462 6450


Authors * He is a Ph.D., Research scholar in Department of Mechanical Engineering, Anna University of Technology Coimbatore, Coimbatore, India. Doing his research under the guidance of Prof.Dr.K.MARIMUTHU, Associate Professor, Department of Mechanical Engineering Coimbatore Institute of Technology, and Coimbatore, INDIA. He received his M.E., Degree at Alagappa Chettiar College of Engineering and Technology, Karaikudi from Anna University, Chennai. He is an Assistant Professor in Department of Mechanical Engineering, Adhiyamaan College of Engineering (Autonomous), Hosur. His research interests include Materials Science in the field of Orthopaedics.

# He received his M.E., and Ph.D., Degree at PSG College of Technology and Coimbatore Institute of Technology from Bharathiyar University in 1999 and 2007. He is an Associate Professor, Department of Mechanical Engg., Assisting HOD to prepare PROJECT PROPOSALS to AICTE//DST, Researcher in Advanced manufacturing Technology, NSS Programme officer and Residential Deputy Warden (CIT Hostel) at Coimbatore Institute of Technology, Coimbator, INDIA. His research interest included in the area of welding, Surface Engineering, Computer Aided PTAW Process Modeling, Material Science, optimization, Reverse Engineering and Rapid Prototyping.

ISSN: 0975-5462 6451

Documents

THRUST FORCE AND TORQUE IN DRILLING THE NATURAL FIBER