 Hello everyone, I am Chandrakant Rathod working as an assistant professor in mechanical engineering department, Walchand Institute of Technology, Solapur. Today we are going to start a new topic sand molding at the end of today's lecture. You are able to understand general properties of base sand different types of base sand molding sand ingredient. The following topic will be discussed in this video lecture introduction to molding sand types of base sand properties of base sand molding sand mixture ingredient coming to the molding sand the molding sand is the principal material used in foundry for making mold which is the mixture of base sand binder water and additives. The molding sands are classified based on the sources ingredient or ingredient into three different types one is the natural sand, second one is the synthetic sand and third one is the special sand why this molding sand is required. We know that in the foundry process we need to create the molding cavity in the molding. So for creating the cavity we will going to have the mold box. So that mold box is consist of two parts one is one is the upper part is the cope and lower part is the drag. So this molding box is also known as a flask in this one we will going to place a pattern in the drag portion and we will going to fill the sand and that sand is rammed around the pattern so that after removing the molding box you will going to have the molding cavity in the mold. So coming to the fifth next topic that is called types of base sand. So first one there are three types of base sands first one is the silica sand in this one silica sand is basically a silicon dioxide SiO2 and some impurities maximum 2% like Al2O3 FeO CaO MgO2 it is available naturally in river beds sea and desert. This type of sand is widely used because of its easy available. So coming to the second base sand that is zircon sand it is basically a zircon silicate ZR SiO2. It has high chemical and thermal stability compared to other sands it is generally used as a facing sand for ferrous casting. Next is the olivine sand it is ortho silicate of iron and magnesium Mg FeO2 O SiO2. So it is suitable for non ferrous always it is available in Norway. Coming to the Kamed sand this is one of the base sand it is produced by calcinating high grade fire clay and crushing it to a required grain size. So it is less expensive than zircon and olivine sand. So it has good thermal stability and high refractoriness. So coming to the next topic that is called properties of base sand. So we will going to discuss some important properties of base sand. So first one is the cohesiveness or it is also called as an strength and permeability flowability cohesive adhesive these are the some properties we will going to discuss in this video. So the important properties of our requirement of base sand is as follow cohesive as strength it is the ability of sand particle to stick together good foundry sand have green strength that is easy handling while molding dry strength to be stable after drying hot strength not to collapse under high temperature metal contact. So coming to the next property that is permeability the property of a sand to allow easy flow of gases and moisture from mold the sand has sufficient porous porosity porous permeability that leads to form a blow hole in the cavity. So permeability here when we pour the molten metal into the cavity. So some gases will going to create in the mold so that gases is easily escape from the mold if it is not some casting defect will going to occur in the product. So it is very important that we have to remove the whatever the gases created in the mold. So coming to the next property that is flowability it is the property of the sand by which it can be easily get squeezed around the pattern and help in compacting to high mold density the sand must flow smoothly while preparing the sand and sand molding cavity. Next property is the adhesiveness it is the property by which the sand particle adhere to the mold box surface and adhere to the neighboring particle. Next property is the refractoriness it is the property by which the sand does not fuse when it come in contact with the molten metal. So another next property is the thermal stability a foundry sand must retain its dimensions under high temperature condition the collapsibility it is also one property after the solidification of the molten metal the mold must be easily collapsible. Next property is the surface finish a good sand must import a fine surface finish to the metal casting. Next property is the reusability a foundry sand must be reusable after reconditioning the next one is the easy to prepare and control a sand must offer a property so that it is easy to prepare and control with other ingredient. So coming to the next topic that is called an molding sand mixture and its ingredients the basic ingredient of molding sands are the base sand binder water and additives the composition and proportion of these ingredients depends on the type of mold sand the first one is the green sand second one is dry sand third one is the loam sand and fourth one is the no big sand. So green sand what is mean by green sand so it is the common foundry sand mixture containing base sand clay water and additives it is also known as green sand why it is called as an green sand means it has some moisture in it so for that we are calling it as a green sand the ingredient of green sands are base sand silica sand that is 80 to 80 to 95 percent binder we are using the bentonite clay 5 to 10 percent and water 4 to 8 percent and some special additives is added in the green sand first one is the coldest wood floor graphite silica floor fuel oil molasses etc. Next is the dry sand it is same as as green sand molding mixture but it is dried after molding in oven to remove the moisture completely large and heavy casting is produced in dry sand mold next one is the loam sand loam sand contains more clay than the green sand and dry sand mixture it contains almost equal amount of base sand and clay the base sand is a fine silica sand we are using here so 30 to 40 percent of fine silica sand we are using and binder here also we are using the bentonite as a bentonite clay 30 to 40 percent water up to 40 percent we are using and some special additives is added in this one graphite silica floor less than 2 percent so coming to the next sand that is no bake sand no bake sand mixtures are uses a cold setting resin as the binder this sand is used for making coarse the mixture gets dried in room temperature itself so these are the some references first one is the foundry technology by opi khanna dhanpatray publication second we manufacturing technology that is data may grow hill manufacturing process by ac niranjan this is a textbook puja publications thanking thank you