Machining Behaviour of Poly Crystalline Diamond Insert on turning GFRP Composites
V.Chockalingam 1, M.Gnanasekar 2, N.Muthukrishnan 3
1,2 - Under graduate student, Department of Mechanical Engineering,Sri Venkateswara College of Engineering, Sriperumbudur – 602 105, Tamilnadu,India
3- Assistant Professor, Department of Mechanical Engineering,Sri Venkateswara College of Engineering, Sriperumbudur – 602 105, Tamilnadu,India. E-mail :firstname.lastname@example.org
In recent years, composite materials are finding increased applications in many engineering applications, and subsequently, the need for accurate machining of composite has increased enormously. Knowledge acquired in machining of ductile materials is not suitable for composites. In the present study, Glass Fiber Reinforced Plastics (GFRP) is machined in medium duty lathe with Poly crystalline Diamond (PCD) of 1600 grade inserts. Various parameters are measured such as Surface finish and power consumed by main spindle. Optimum parameters are determined from graph. By using optimum parameters tool wear was studied for about 25 minutes. Result provides some useful information. Machining with PCD gives good surface finish at higher cutting speeds with medium depth of cut and feed. Scanning Electron Microscopic (SEM) images also shown.
Key words: GFRP, Turning, PCD, power consumed, surface finish, tool wear
Composite materials are continuously displacing traditional engineering materials because of their high specific stiffness, high specific strength, high damping and low coefficient of thermal expansion. The Glass Fiber reinforced Plastic (GFRP) composites are extensively used in many applications such as power plants, Waste and waste water, etc.These GFRP application fields need the machining opportunity like drilling, milling, cutting off, etc which has increased for its development. However the industries faced difficulties to machine these composites, because knowledge and experiences acquired for conventional materials cannot be applied for composites. Machinability of these composites completely different from that of conventional materials 
For the past 25 years, outcome of the machining of GFRP composites has been reviewed. The researchers investigated the machining of fiber reinforced plastics using various machining process like drilling, routing and laser cutting they found that machining of GFRP is different from conventional materials in many aspects. They reported that, the metal behavior is not only inhomogeneous, but also dependent on fiber and matrix properties, and type of weave. Some researchers  studied the theoretical work on chip formation, cutting force and surface quality in orthogonal cutting with varied fiber angles. Some others  studied the tool wear, surface finish and mechanism of metal removal. Only limited amount of literature exists on machining of GFRP composites. Most of the studies on GFRP machining shows that minimizing the tool wear and surface roughness was very difficult and is to be controlled. In this aspect a detailed study is carried on machining GFRP composites on medium duty lathe with Poly Crystalline Diamond (PCD) insert.
Machining tests were conducted with different cutting conditions on the composites. Samples were obtained from local market in the form of hollow cylindrical rods of outside diameter 50 mm and inside diameter 20 mm, and length 120 mm. The material specification fiber, resin and mechanical properties of composites used in this work are given in Table 1 and 2. The tool holder used was PCLNR 25 25 M 12. The PCD insert was of geometry CNMA 120408, which is the commonly used inserts geometry for general turning application. The tool material was PCD 1600 medium grade Medium duty lathe was used for the turning tests.
The machining of the fabricated...
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