 Hello friends, myself Dr. Narendra Kartikar, Assistant Professor, Department of Mechanical Engineering, Valachandra Institute of Technology, Solapur. Today, we are going to see the particularly discussion and presentation on study of core learning outcome. At the end of this lecture or the session, student will be able to understand the different type of cores and also know where to apply it. Let us see the content of particularly presentation, introduction, we will see about the core, its type, different function, purpose of the cores, essential characteristics of dry sand core, type of cores, method of making the cores. You can see the particular diagram shown on the screen where the cross section of molding box is there. You can see the presence of core over there. The core is placed over there with the support of chaplets. Normally, the core is going to be present over there to produce the hollow geometry for the casting. Section diagram of casting mold is shown on the screen where once again a different kind of type of core and its placement can be visible over there. You can see the different parts in the section diagram of casting mold. The cope hub, drag hub and in between that particular those two cope and drag hub molds, the different kind of cavities and elements are present. The brown color part is shown over here that is a core. The core is placed over there in a vertical position. These two diagrams just I had shown to imagine how the particular cores can be placed and its importance to produce the hollow geometry in the casting. Let us go with the introduction of the core. Core is an obstruction which when positioned in the mold naturally does not permit the molten metal to fill up the space occupied by the core. In this way, a core produces hollow casting. Cores are required to create the recesses, undercuts and interior cavities that are often a part of castings. A core may be defined as a sand shape or form which makes the contour of a casting for which no provision has made in the pattern of molding. Cores may be made up of sand, metal, plaster or ceramics. Different functions are the purpose of the core that can be included in the mold itself. For hollow casting cores provide the mean of forming the main internal cavities. Not only that, but cores may be provide external undercut features. May be employed to improve the mold surfaces. May be inserted to achieve deep recesses in the casting. Another main function is to use to strengthen the molds. Cores may be used to form the gating system of large size molds also. Let us go with the essential characteristics of dry sand core. The core must possesses sufficient strength to support itself and to get handled without breaking. High permeability to let the mold gases escape through the mold walls. Smooth surface to ensure a smooth casting. High refractoriness to withstand the action of hot molten metal. High collapsibility in order to assist the free contraction of solidifying metal. Those ingredients which do not generate the mold gases. At this stage of this session, are you able to recall or share some of the casting parts where hollow geometries are present? Enlist such casted parts which you had seen earlier anywhere in real time. Just enlist few of them. Let us go with the type of cores. The cores may be classified according to the state or condition of core that is green sand, dry sand, no big sand. It can be also classified the nature of core material employed that is oil bonded, resin bonded, shell cores and sodium silicate cores. The classification depending on the type of core hardening processes that is CO2 process, the hot box process, cold set process and so on. The shape and position of the core is also another factor with which we can classify the various type of cores. Horizontal core, vertical core, hanging or cover core, balanced core, drop core or stop of core, ram up core and kiss core. Let us go on the discussion of particular type of cores with the position or the placement of cores. First one horizontal core. A horizontal core is positioned horizontally in the mold as shown in the figure. A horizontal core may have any shape circular or some of the other section depending on the shape of the cavity required in the casting. A horizontal core is supported in core seat at both its ends. Uniform sectioned horizontal cores are generally placed at the parting line. A horizontal core is very commonly used in the foundries. You can more elaboratively understood through the means of the image shown on the screen. The second type of core is a vertical core. On the cove side, a vertical core needs more taper so as not to tear the sand in the cove while assembling cove and drag half. It is positioned in the mold cavity with its axis vertical. The two ends of vertical cores are supported in core seat in cove and drag respectively. A big portion of vertical core usually remains in the drag. More understanding through the image shown on the screen. Hanging or cover core. It is known as hanging core because it hangs. It is also called cover core if it covers the mold and rest on a seat made in the drag. A simple hanging core is one which is not supported on any seat rather it hangs from the cove with the help of wires. A hanging core is provided with a hole through which the molten metal reaches the mold cavity. Hanging cores can be made up of either green or dry sand. The image shown on the screen will elaborate more for the hanging or cover core. Balanced core. A balanced core is one which is supported and balanced from its one end only. A balanced core requires a long core seat so that the core does not sag or fall into the mold. A balanced core is used when a casting does not want a through cavity. The image is further more clarify your concept. Drop or stop of core. A stop of core is employed to make a cavity in the casting which cannot be made with either type of cores. A stop of core is used when a hole recess or cavity requires in a casting is not in line with the parting surface rather it is above or below the parting line of the casting. Depending on its shape and use a stop of core may be known as tail core, saddle core, chair core etc. Ram up core. A ram up core is one which is placed in the sand along with the pattern before ramming the mold. A ram up core cannot be placed in the mold after the mold has been rammed. It is used to make internal or external surface details of the casting. It is more elaboratively self-explanatory figure shown on the screen. Key score. A key score does not require a core seat for getting supported. It is held in a position between drag and cope due to the pressure exerted by cope on the drag. A number of key score can be simultaneously positioned in order to obtain a number of holes in the casting. The image is self-explanatory more about the key score. Method of making the cores. Normally, the steps involved, cores and preparation, making the cores, baking the cores, finishing of the cores and setting the cores. The few of the figures are self-explanatory about these steps. Some of the references for these presentations are introduction to basic manufacturing processes and workshop technology by Rajinder Singh, a textbook of workshop technology manufacturing processes by Khurmi Gupta. Thank you.