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SRI LANKA INSTITUTE OF INFORMATION TECHNOLOGY ENGINEERING SKILL DEVELOPMENT (ME103)
INTRODUCTION TO LATHE MACHINE
Name: R.A.C.J.SENEVIRATNE Student ID: EN13517984 Group: 5
Mr. Niranga Silva Mr. A.K. Mahaarachchi Lecturer in charge: Prof. Chandana Perera
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ME103 Engineering Skill Development Introduction to Lathe Machine Objective To familiarize the operations of lathe machine Introduction Lathe is a machine, which removes the metal from a piece of work to the required shape and size. The origin of turning lathes goes to around 1300 BC when the Egyptians first developed a two-person lathe. One person turned the wood work piece with a rope while the other used a sharp tool to cut shapes in the wood. The Romans improved the Egyptian design with the addition of a turning bow. Early bow lathes were also developed and used in Germany, France and Britain. In the Middle Ages a pedal replaced hand-operated turning, freeing both the craftsman's hands to hold the woodturning tools. The pedal was usually connected to a pole, often a straight-grained sapling. The system today is called the "spring pole" lathe (Pole-lathe). During the industrial revolution, mechanized power was applied to the lathe via steam engines and line shafting, allowing faster and easier work. Between the late 19th and mid-20th centuries, individual electric motors at each lathe replaced line shafting as the power source. Beginning of 1950s, servomechanisms were applied to the control of lathes and other machine tools via numerical control (NC)
There are different types of lathes available in the market. Following is a schematic diagram of a lathe machine.
Figure 1: Components of a Lathe
The schematic diagram of the lathe machine available at SLIIT mechanical workshop is given below.
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Figure 1: Lathe at SLIIT
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Briefly describe the types of lathe machines.
There are different types of lathes machines for different purposes. 1. Light Duty Lathe Machine Light duty lathe machines are generally lathe machines of small size with a swing of 10 inches or less, mounted to a bench or table top. The light duty lathe machines are made of quality tested material and is used in electronic, electrical and automobile industries. The light duty lathe machines can be used in almost all machining jobs but may be limited due to the size of the material that can be turned. 2. Medium Duty Lathe Machines The medium duty lathe machines consist of a strong bed casting made of close grained cast iron. Even under high pressure and heavy load, these medium duty lathe machines can give best performance without vibrations. These medium duty lathe machines can be used in different industrial and mechanical applications like turning, shaping, facing, boring and threading of all kinds of metals 3. Heavy Duty Lathe Machine The heavy duty lathe machines are manufactured from highest grades of material like iron and steel. This type of lathe machine is designed for performing many tasks efficiently like screw cutting, sliding and surfacing operations. The heavy duty lathe machine has dimensional accuracy due to which it ensures high tensile strength and longer service life. Moreover, heavy duty lathe machines are quite easy to install and operate. 4. Extra Heavy Duty Lathe Machine
5. Turret Lathes. These types of lathes are used for machining single workpieces sequentially. This means that several operations are needed to be performed on a single work piece. With the turret lathes, sequential operations can be done on the work piece, eliminating errors in work alignment. With this set-up, machining is done more efficiently. Correspondingly, time is saved because there is no need to remove and transfer the work piece to another machine anymore. 6. Engine Lathe
5 7. Punch card Lathe The punch card lathe is used to carve cruxite dowels with patterns, which are dictated by punched cards and pre-punched cards. The lathe, in combination with the punch Designix and Alchemiter , allows players to alchemize objects, such as the Cruxite artifacts used to enter The Medium, various weapons and outfits, and other miscellaneous objects.
8. Toolroom Lathe A toolroom lathe is a lathe optimized for toolroom work. It is essentially just a top-of-theline center lathe, with all of the best optional features that may be omitted from less expensive models, such as a collet closer, taper attachment, and others. There has also been an implication over the years of selective assembly and extra fitting, with every care taken in the building of a toolroom model to make it the smoothest-running, most-accurate version of the machine that can be built. However, within one brand, the quality difference between a regular model and its corresponding toolroom model depends on the builder and in some cases has been partly marketing psychology. For name-brand machine tool builders who made only high-quality tools, there wasn't necessarily any lack of quality in the base-model product for the "luxury model" to improve upon.
9. All Geared Lathe Machine 10. Metal Spinning Lathe Metal spinning, also known as spin forming or spinning or metal turning most commonly, is a metalworking process by which a disc or tube of metal is rotated at high speed and formed into an axially symmetric part. 11. CNC (Computer numerical controlled) Lathe Machine
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Briefly describe the operations which can be performed using a lathe machine.
Facing Facing is when you remove wood or metal from a cylindrical work piece. This creates a smooth surface. However, if you use a chuck you can face rectangular, square or other unusual-shaped pieces. When facing, begin with a slower speed and gradually increase to a faster speed. Also, the work piece should not extend farther out of the lathe than around three times its own size. When facing, gouges, parting and chisel tools can be used to create the desired results.
Turning Turning is when a turning tool is applied to the work piece to create groves, ridges and indents in the work piece. Turning creates metal or wood chips as the piece turns on the lathe. The work piece spins between two end points to hold it in place. The speed can be adjusted as necessary depending on the size of the work piece and the desired results. Such tools to use are a captive ring chisel, a decorative bead chisel or a scraper.
Boring Boring is enlarging an existing hole. The hole can be a drilled, molded, cast or a forged hole. The work piece is placed in the lathe chuck and will be spinning while the boring tool is slowly driven into the opening. Boring tools are cylindrical in shape and will have a cutting tool protruding from them. Two different boring tools can be mounted together to make two different cuts at one time.
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Briefly describe different types of work holding devices used to hold a work piece in a lathe machine.
1. Independent Chuck - (4 Jaw) This is independent chuck generally has four jaws, which are adjusted individually on the chuck face by means of adjusting screws. 2. Universal Scroll Chuck - (3 Jaw) It usually has three jaws, the jaws are moved simultaneously within the chuck. 3. Collet Chuck A cone-shaped chuck used for holding cylindrical pieces in a lathe 4. Magnetic chuck Thin jobs can be held by means of magnetic chucks. 5. Power Chuck 6. 2 Jaw Chuck
7. Face Plate A lathe faceplate is the basic work holding accessory for a metal turning lathe. It is a circular metal (usually cast iron) plate which fixes to the end of the lathe spindle. The work piece is then clamped to the faceplate, typically using t-nuts in slots in the faceplate, or less commonly threaded holes in the faceplate itself.
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What do you mean by CNC lathe machine?
Computer Numerical Control (CNC) is one in which the functions and motions of a machine tool are controlled by means of a prepared program containing coded alphanumeric data. CNC can control the motions of the work piece or tool, the input parameters such as feed, depth of cut, speed, and the functions such as turning spindle on/off, turning coolant on/off.
The applications of CNC include both for machine tool as well as non-machine tool areas. In the machine tool category, CNC is widely used for lathe, drill press, milling machine, grinding unit, laser, sheet-metal press working machine, tube bending machine etc. Highly automated machine tools such as turning center and machining center which change the cutting tools automatically under CNC control have been developed. In the non-machine tool category, CNC applications include welding machines (arc and resistance), coordinate measuring machine, electronic assembly, tape laying and filament winding machines for composites etc These lathes are rapidly replacing the older production lathes due to their ease of setting, operation, repeatability and accuracy. They are designed to use modern carbide tooling and fully use modern processes. The part may be designed and the tool paths programmed by the CAD/CAM process or manually by the programmer, and the resulting file uploaded to the machine, and once set and trialed the machine will continue to turn out parts under the occasional supervision of an operator. The machine is controlled electronically via a computer menu style interface. The program may be modified and displayed at the machine, along with a simulated view of the process. The setter/operator needs a high level of skill to perform the process, however the knowledge base is broader compared to the older production machines where intimate knowledge of each machine was considered essential. These machines are often set and operated by the same person, where the operator will supervise a small number of machines. The design of a CNC lathe varies with different manufacturers, but they all have some common elements. The turret holds the tool holders and indexes them as needed, the spindle holds the work piece and there are slides that let the turret move in multiple axis simultaneously. The machines are often totally enclosed, due in large part to safety issues.
