Advanced Research Journals of Science and Technology
ADVANCED RESEARCH JOURNALS OF SCIENCE AND TECHNOLOGY
(ARJST)
PREDICTIVE ANALYSIS OF MILL CUTTERS FOR IMPROVED SURFACE FINISH QUALITY AND EFFECTS OF COOLANT ON CARBIDE TOOLS
2349-1845
Hemanth1, Muralidharan2, 1 Research Scholar, Department of Mechanical Engineering,CISTCE,Bangalore,India 2 Professor , Department of Mechanical Engineering, CISTCE,Bangalore,India. .
Abstract Aim of the project is to analyze the surface finish quality of work piece by varying cutter types to suggest the optimum cutters for various metal cutting and also this project work deals with the effect of coolants on carbide cutters life. The entire project work will be carried out in REGINSON ENGINEERING PVT LTD industry in practical approach. The following steps will be carried to achieve the aim of the project. Data collection and literature surveying will be done to understand the approach. Work piece will be prepared for experimental analyzing .milling operation will be done using different cutters with variation of work piece material. Various coolants are used on a standard milling process. Measurements of surface finish and mill cutters will be done to determine the quality. Conclusion will be prepared using above results. *Corresponding Author:
INTRODUCTION TO CUTTING TOOLS
Hemanth, Research Scholar, Department Of Mechanical Engineering, CISTCE,Bangalore,India
Cutting is the separation of a physical object, or a portion of a physical object, into two portions, through the application of an acutely directed force. An implement commonly used for cutting is the knife or in medical cases the scalpel. However, any sufficiently sharp object is capable of cutting if it has a hardness sufficiently larger than the object being cut, and if it is applied with sufficient force. Cutting also describes the action of a saw which removes material in the process of cutting.
Published: August 14, 2014 Review Type: peer reviewed Volume: I, Issue : II Citation: Hemanth,Research Scholar (2014) PREDICTIVE ANALYSIS OF MILL CUTTERS FOR IMPROVED SURFACE FINISH QUALITY AND EFFECTS OF COOLANT ON CARBIDE TOOLS
INTRODUCTION Milling is the process of cutting away material by feeding a work piece past a rotating multiple tooth cutter. The cutting action of the many teeth around the milling cutter provides a fast method of machining. The machined surface may be flat, angular, or curved. The surface may also be milled to any combination of shapes. The machine for holding the work piece, rotating the cutter, and feeding it is known as the Milling machine. CUTTING AND FEED MOVEMENTS Milling is a forming operation whereby chips are removed using a cutting tool known as a "milling cutter". This has several cutting edges laid out around its axis of rotation, and is subjected both to a rotational movement and a feed motion. This type of operation is carried out on what is called a milling machine.
Cutting is a compressive and shearing phenomenon, and occurs only when the total stress generated by the cutting implement exceeds the ultimate strength of the material of the object being cut. The simplest applicable equation is stress = force/area: The stress generated by a cutting implement is directly proportional to the force with which it is applied, and inversely proportional to the area of contact. Hence, the smaller the area (i.e., the sharper the cutting implement), the less force is needed to cut something. "Cutting" may also refer to a method used in plant propagation. It involves cutting a part of the plant - typically a healthy shoot - with any sharp and sterile device, and then placing the removed part in water, where it grows roots before transplanting into potting soil. Some cuttings do not require water but are able to grow immediately in vermiculite or potting soil. CUTTING TOOLS A cutting tool (or cutter) is any tool that is used to remove material from the work piece by means of shear deformation. Cutting may be accomplished by single-point or multipoint tools. Single-point tools are used in turning, shaping, planning and similar operations, and remove material by means of one cutting edge. Milling and drilling tools are often multipoint tools. Grinding tools are also multipoint tools. Each grain of abrasive functions as a microscopic single-point cutting edge (although of high 11
Advanced Research Journals of Science and Technology
negative rake angle), and shears a tiny chip.
heavy and stiff machinery.
Cutting tools must be made of a material harder than the material which is to be cut, and the tool must be able to withstand the heat generated in the metal-cutting process. Also, the tool must have a specific geometry, with clearance angles designed so that the cutting edge can contact the workpiece without the rest of the tool dragging on the workpiece surface. The angle of the cutting face is also important, as is the flute width, number of flutes or teeth, and margin size. In order to have a long working life, all of the above must be optimized, plus the speeds and feeds at which the tool is run.
Unstable materials, being generally softer and thus tougher, generally can stand a bit of flexing without breaking, which makes them much more suitable for unfavorable machining conditions, such as those encountered in hand tools and light machinery.
TYPES Linear cutting tools include tool bits (single-point cutting tools) and broaches. Rotary cutting tools include drill bits, countersinks and counterbores, taps and dies, milling cutters, and reamers. Other cutting tools, such as handsaw blades and fly cutters, combine aspects of linear and rotary motion. CUTTING TOOL INSERTS Cutting tools are often designed with inserts or replaceable tips (tipped tools). In these, the cutting edge consists of a separate piece of material, either brazed, welded or clamped on to the tool body. Common materials for tips include tungsten carbide, polycrystalline diamond, and cubic boron nitride. Tools using inserts include milling cutters (endmills, fly cutters), tool bits, and saw blades. MATERIALS To produce quality parts, a cutting tool must have three characteristics: • Hardness — hardness and strength at high temperatures. • Toughness — toughness, so that tools don’t chip or fracture. • Wear resistance — having acceptable tool life before needing to be replaced. Cutting tool materials can be divided into two main categories:STABLE and UNSTABLE. Unstable materials (usually steels) are substances that start at a relatively low hardness point and are then heat treated to promote the growth of hard particles (usually carbides) inside the original matrix, which increases the overall hardness of the material at the expense of some its original toughness. Since heat is the mechanism to alter the structure of the substance and at the same time the cutting action produces a lot of heat,such substances are inherently unstable under machining conditions. Stable materials (usually tungsten carbide) are substances that remain relatively stable under the heat produced by most machining conditions, as they don't attain their hardness through heat. They wear down due to abrasion, but generally don't change their properties much during use. Most stable materials are hard enough to break before flexing, which makes them very fragile. To avoid chipping at the cutting edge, most tools made of such materials are finished with a slightly blunt edge, which results in higher cutting forces due to an increased shear area. Fragility combined with high cutting forces results in most stable materials being unsuitable for use in anything but large,
MILLING CUTTER Milling cutters are cutting tools used in milling machines or machining centers. They remove material by their movement within the machine (eg: a ball nose mill) or directly from the cutters shape (a form tool such as a Hobbing cutter). FEATURES OF A MILLING CUTTER Milling cutters come in several shapes and many sizes. There is also a choice of coatings, as well as rake angle and number of cutting surfaces. • Shape: Several standard shapes of milling cutter are used in industry today, which are explained in more detail below. • Flutes / teeth: The flutes of the milling bit are the deep helical grooves running up the cutter, while the sharp blade along the edge of the flute is known as the tooth. The tooth cuts the material, and chips of this material are pulled up the flute by the rotation of the cutter. There is almost always one tooth per flute, but some cutters have two teeth per flute. Often, the words flute and tooth are used interchangeably. Milling cutters may have from one to many teeth, with 2, 3 and 4 being most common. Typically, the more teeth a cutter has, the more rapidly it can remove material. So, a 4-tooth cutter can remove material at twice the rate of a 2-tooth cutter. • Helix angle: The flutes of a milling cutter are almost always helical. If the flutes were straight, the whole tooth would impact the material at once, causing vibration and reducing accuracy and surface quality. Setting the flutes at an angle allows the tooth to enter the material gradually, reducing vibration. Typically, finishing cutters have a higher rake angle (tighter helix) to give a better finish. • Center cutting: Some milling cutters can drill straight down (plunge) through the material, while others cannot. This is because the teeth of some cutters do not go all the way to the centre of the end face. However, these cutters can cut downwards at an angle of 45 degrees or so. • Roughing or Finishing: Different types of cutter are available for cutting away large amounts of material, leaving a poor surface finish (roughing), or removing a smaller amount of material, but leaving a good surface finish (finishing). A roughing cutter may have serrated teeth for breaking the chips of material into smaller pieces. These teeth leave a rough surface behind. A finishing cutter may have a large number (4 or more) teeth for removing material carefully. However, the large number of flutes leaves little room for efficient scarf removal, so they are less appropriate for removing large amounts of material. • Coatings: The right tool coatings can have a great influence on the cutting process by increasing cutting speed and tool life, and improving the surface finish. Polycrystalline Diamond (PCD) is an exceptionally hard coating used on cutters which must withstand high abrasive wear. A PCD coated tool may last up to 100 times longer than an uncoated tool. However the coating cannot be used at temperatures above 600 degrees C, or on ferrous metals. Tools for machining Aluminum are sometimes given a coating of TiAlN. Aluminum is a relatively sticky metal, and can weld itself to the teeth of tools, causing them to
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Advanced Research Journals of Science and Technology
appear blunt. However it tends not to stick to TiAlN, allowing the tool to be used for much longer in Aluminum. • Shank: The shank is the cylindrical (non-fluted) part of the tool which is used to hold and locate it in the tool holder. A shank may be perfectly round, and held by friction, or it may have a Weldon Flat, where a grub screw makes contact for increased torque without the tool slipping. The diameter may be different from the diameter of the cutting part of the tool, so that it can be held by a standard tool holder. TYPES OF MILLING CUTTERS
raw ingredients. Depending on context and on which type of cutting fluid is being considered, it may be referred to as cutting fluid, cutting oil, cutting compound, coolant, or lubricant. Most metalworking and machining processes can benefit from the use of cutting fluid, depending on work piece material. Common exceptions to this are machining cast iron and brass, which are machined dry. The properties that are sought after in a good cutting fluid are the ability to: Keep the work piece at a stable temperature (critical when working to close tolerances). Very warm is OK, but extremely hot or alternating hot-and-cold are avoided. Maximize the life of the cutting tip by lubricating the working edge and reducing tip welding. Ensure safety for the people handling it (toxicity, bacteria, fungi) and for the environment upon disposal.
• Slot, • End mill and • Ballnose cutters END MILL End mills (middle row in image) are those tools which have cutting teeth at one end, as well as on the sides. The word end mill is generally used to refer to flat bottomed cutters, but also include rounded cutters (referred to as ball nosed) and radii used cutters (referred to as bull nose, or torus). They are usually made from high speed steel (HSS) or carbide, and have one or more flutes. They are the most common tool used in a vertical mill.
TYPES OF COOLANTS USED IN EXPERIMENT
SLOT DRILL Slot drills (top row in image) are generally two (occasionally three or four) fluted cutters that are designed to drill straight down into the material. This is possible because there is at least one tooth at the centre of the end face. They are so named for their use in cutting keyway slots. The term slot drill is usually assumed to mean a two fluted, flat bottomed end mill if no other information is given. Two fluted end mills are usually slot drills, three fluted sometimes are not, and four fluted usually are not. BALL NOSE CUTTER Ball nose cutters (lower row in image) are similar to slot drills, but the end of the cutters is hemispherical. They are ideal for machining 3-dimensional contoured shapes in machining centers, for example in moulds and dies. They are sometimes called ball mills in shop-floor slang, despite the fact that that term also has another meaning. They are also used to add a radius between perpendicular faces to reduce stress concentrations. COOLENTS Cutting fluid is a type of coolant and lubricant designed specifically for metalworking and machining processes. There are various kinds of cutting fluids, which include oils, oil-water emulsions, pastes, gels, aerosols (mists), and air or other gases. They may be made from petroleum distillates, animal fats, plant oils, water and air, or other
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Advanced Research Journals of Science and Technology
MATERIAL PROPERTIES
4). K.B. Ahsan, A.M. Mazid, R.E. Clegg, G.K.H. Pang Central Queensland University, School of Engineering and Built Environment, Rockhampton, Australia Corresponding e-mail address: k.ahsan@cqu.edu.au
RESULTS Type of tool
Type of coolent
Roughness finishing(Ra)
S.S Steel+ Carbide tool
Fuchs coolent oil
0.9
S.S Steel+ Carbide coated tool
Fuchs coolent oil
1.02
S.S Steel+ Carbide tool
Hocut coolent oil
0.3
S.S Steel+ Carbide coated tool
Hocut coolent oil
0.5
S.S Steel+ HSS tool
Hocut coolent oil
0.7
CONCLUSION This project /research work deals with predictive analysis of mill cutters for improved surface finish quality and on “effects of coolant on carbide tools”. Initially literature survey & data collection is done on cutters and coolants to understand methodology. In the next stage practical approach is done on work piece milling using carbide, carbide coated and HSS tools. In the next stage milling operation is done by varying work piece materials. (SS, S130, S80 and Inconal). In the next stage milling is done by varying coolants. Surface finish has been checked and recorded for all the work pieces. As per the above experiment results this project work concludes that “Hocut coolant oil” with 1:10 ratio provides the sufficient cooling effect to obtain optimum surface finish. For hard materials like SS, S130 & Inconal is better to use carbide tools to obtain good quality surface finish. For medium hard materials like S-80 better to use carbide coated tools to obtain good quality of surface finish. For medium/hard materials carbide tools preventing thermal transportation from milling area due to that medium hard material are not giving optimum surface finish with carbide tools. REFERENCES 1).S.E. Cordes a Laboratory for Machine Tools and Production Engineering, RWTH Aachen University, Germany 2). Journal of Mechanical Engineering Amar Sebhi1,* – Hocine Osmani1 – Joel Rech2 1 Optics and Precision Mechanics Institute, University of Ferhat Abbes, Setif, Algeria 2 Laboratory LTDS National School of Engineering, Saint Etienne, France 3).1Issac Thamban, 2Biju Cherian Abraham, 3Sabu Kurian 1,2,3,Assistant Professor, Mar Athanasius College of Engineering, Kothamangalam,
5). Sonawane Gaurav Assistant Professor, Mechanical Deptt., Sandip Foundations’s, Sandip Institute of Technology and Research Center, Nasik. V. G. Sargade, Ph.D Professor, Mechanical Engineering Department, Dr. B.A.T. University, Lonere, Raigad. (M.S.) 6). Anand Kumar1, Pardeep Kumar2, Anuj Kumar3 , Bhupender Singh4 1, 3, 4Assistant Professor, Department of Mechanical Engineering, Panipat Institute of Engineering and Technology, Panipat, Haryana, India 2Assistant Professor, Department of Mechanical Engineering, Deen Bandhu Chhotu Ram University of Science and Technology, Murthal, Sonepat, Haryana, India anand_kumar407@yahoo.co.in, psharma.dcrust@gmail.com, phenom87@gmail.com, bhupender1007@gmail.co 7). Rohit Uppal1, Dilbag Singh2 and Sunil Kumar3 1Department of Mechanical Engineering, Vaishno College of Engineering &Technology, Thapkour, Himachal Pradesh 2,3Department of Mechanical Engineering, Beant College of Engineering & Technology Gurdaspur–143521, Punjab 8). Prof. K.P.Maity Prof.B.D.Sahoo Dept.of Mechanical Engg. Nit,Rourkela I.G.I.T,Sarang 9). Vikas Verma PG Scholar, Department of Mechanical Engineering, Chouksey Engineering College, Bilaspur(C.G.) 10). BASIM A. KHIDHIR*, BASHIR MOHAMED Department of Mechanical Engineering, Faculty of Engineering, Universiti Tenaga Nasional, Malaysia *corresponding Auther: basim@student.uniten.edu.my
AUTHOR Hemanth, Research Scholar, Department of Mechanical Engineering, CISTCE,Bangalore,India.
Muralidharan, Professor , Department of Mechanical Engineering, CISTCE,Bangalore,India.
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