Casting off the old technique is the quickest link Between 2nd manufacturing engineering drawing .It Provides us with the possibility of forming wide range of shapes with wide range of materials. sand casting is simply Melting the metal and pouring it INTO a preformed cavity, Called mold, allowing (the metal to solidify and Then breaking up the mold to remove casting. In sand casting expandable molds are Used. So for each casting operation are i have to form a new mold. Basic Requirements for metal casting
1. A mold cavity
2. Melting process
3. Pouring technique
4. Solidification process
5. Removal of casting
6. Finishing draft allowance.
Sand Casting is the MOST important ‘and mostly Cars casting technique. To Perform sand casting we do i have to form a pattern (a full sized model of the part), enlarged to account for shrinkage and machining allowances in the final casting. Materials Used to Make Patterns Include wood, plastics, aluminum, fiberglass, cast iron and Some other metals. Wood is a common pattern material Because it is easily. Worked INTO shape. Its disadvantages are That it tends to warp and the sand Being compacted around it abrades it, setup Limiting the number of times it whence be reused (Used for a small number of castings). Metal Patterns are more expensive to Make, BUT not * Much longer cargo. For example aluminum is the MOST common metal to be Used in f “work schedule castings are to be made by the Same pattern. So selection of the Appropriate pattern material depends to a large extent on the Total Quality of castings to be made. The size of the pattern depends upon the shrinkage Düring cooling and the Finishing allowance. Some special coating to Prevent Their Destruction shouldnt coat Patterns. Patterns i ar Some identifiers thrown out colors on dis, each of Which DG Different Meaning That represent Different treatments and requirements Far the Patterns. The casting will be Missing. To ensure That cores retain the Correct arrangement core Prints are placed Into the mold. Some metal springs Called densiments are placed Into the mold Io Provide Uniform solidification of the metal throughout the mold. Nails are inserted INTO thin parts of the mold to reinforce dis. After forming the mold cavity, the liquid is sprayed Alcoholic aver the cope (The upper part of the mold) and heated with flames to harden and to dry the surface.
Filling a metal box Having two halves, Which is Called the flask mold forms. So ar mold made up of two halves, Which is separated by a parting line. The Reason for this is to remove the part tasted easier for from the mold. The upper part of the mold Called the cope and the lower part Called the drag. The cope and drag are prepared separately and are ready not * not * When unites and metal is poured through a canal it INTO Called sprue, Which transmits the molten metal via Into the mold cavity runner. The runner shouldnt be big Because it will Increase the Amount of the waste metal. It shouldnt be small Because this enhances rapid solidification in the runner causing a blockage. At the bottom of the sprue there is a gap Far well Called the collection of the unwanted sand, Which comes with the flowing metal. There ar a riser system, Which acts from the inventory of molten metal When the mold cavity is fulfilled with the metal and Automatically feeds the cavity of the part I want to Get That we do.
Because this system is Essential for the molten metal cools it down this shrinks the Amount Needed to Replace the metal shrinked Comes fom the riser itself eliminating shrinkage cavities. A casting microporosity May show. This sing with directional solidification be eliminated either by incorporating a metal cell Into the mold or by tapering the thinnest section of the runner. You Chills ar Used around thicker parts of the casting to Provide Uniform cooling of the cooler parts These thinner parts to Prevent cracks. Chills, by this way, preserve the mechanical properties of the casting siar. The steel is melted in electric-arc Furnaces. The Advantage of electrical furnace, the scrap steel, Which wasnt Used Estimates for (metal risers and runners left In) sing in These Furnaces be melted and used again. When the furnace reaches the drink to temperature, it is Turned off. The molten metal is Filed Portable RESERVOIR Called Into the table and Then table is moved to just Above of the mold and metal is poured Into the mold’s pouring basin. A powder is added to the mold’s surface to Prevent metal’s rapid cooling pouring Düring. Another powder is sprayed aver the mold to form a blanket of inert gas to Prevent the oxidation of the molten metal. The steel is melted in electric-arc Furnaces. The Advantage of electrical furnace, the scrap steel, Which wasnt Used Estimates for (metal risers and runners left In) sing in These Furnaces be melted and used again.
When the furnace reaches the drink to temperature, it is Turned off. The molten metal is Filed Portable RESERVOIR Called Into the label and Then table is moved to just Above of the mold and metal is poured Into the mold’s pouring basin. A powder is added to the mold’s surface to Prevent metal’s rapid cooling pouring Düring. Another powder is sprayed aver the mold to form a blanket of inert gas to Prevent the oxidation of the molten metal. Completed The casting is left for cooling and When it completely cools down the siar flask is wrangled to a vibrating platform to remove the casting from the mold. Excess parts are cut either by oxygen in f the casting is of steel (high), or by hammering in f the casting is of cast iron.