 Hello everyone, I am Chandrakant Rathod working as an assistant professor in the Mechanical Engineering Department, in the Interest of Technology, Sallapur. Today we are going to start a new topic that is called casting defect. At the end of today's lecture, you are able to understand what is casting defect, different types of casting defect, casting defect causes and remedies. The following topics will be discussed in this video lecture. Definition of casting defect, reason for defects in casting, types of casting defects. So first coming to the definition of the casting defect. Casting defect is defined as the imperfections or flow that exist on the surface or subsurface of a solidified casting. Casting defects are usually not accident, they occur because some steps in the manufacturing cycle does not get properly controlled and somewhere goes wrong. Close control and standardizations of all aspects of manufacturing techniques offers the best defense against the occurrence of defects in casting. So no casting can be free from imperfections, they are considered as defect when they exceeds the shape, size, dimension and functional requirements beyond the acceptable inspection and quality standard. So these are the some reasons for defects in casting. So defects caused by patterns and molding box equipment, defects due to improper molding and core making material, defects due to improper sand mixing and distribution, defects caused by molding cores, gating etc. Defects due to improper mold drying and core baking, defects caused by molten metal, defect due to faulty heat treatment, defect due to cast metal, defect occurring during the fat length. So we will going to discuss one by one. So first one is the defect caused by pattern, patterns and molding box equipment. So these are the some three, four defects are there, mismatch or mold shift. So it produce a casting which does not match at the parting line, there is a mismatching of top or bottom part of the casting at the mold joint. So some causes are there, var are loose doll in pattern made in hulls, faulty registering of top and bottom hulls of patterns mounted on plate. So what are the remedies for removing this one is, we have to remove one out loose band or ill fitting molding box clamping pins. So second one is the crush, it is the displacement of sand while closing a mold box thereby deforming a mold surface. A crush shows itself as an irregular sandy depression in the casting. So some causes are core prints too small for the core, core too large for the core print, careless assembly of molding boxes and cores. So next one is the defect due to improper molding and core making, so material. So blow hole is the one of the defect in this one. Blow holes are smooth round holes, blow holes are entrapped bubbles of gas with a smooth wall and causes are these excessive moisture in the molding sand, low permeability and excessive fine grain sands and extra hard rammed sands. So remedies is improve permeability of the mold and cores avoid excessive ramming of the molding sand, pin holes. So pin holes are very small revel on the surface of casting after the surface has been cleaned by short blasting. So causes are sand with high moisture contains faulty metal mold reactions, remedies this should be can be removed by improving permeability of the mold or cores and good venting practice. Hot tears they are internal and external cracks having rigid edges. It is formed in casting by contraction stress just at the end of the solidification. So causes are excessive mold hardness, faulty pattern and casting design, poor design of gatings and risers. Remedies are use of cores with moderate hot strength, increasing collapsibility of the cores, good design of casting and feeding system. So next defect is the defect caused by molding, core and gating system. In this one coal laps. If molten metal is too cold or casting section is too thin, entire mold cavity may be filled during pouring before the metal starts solidifying and the result in misrun. Causes too cold molten metal, too thin casting section, too small gates, metal locking in fluidity and slag holes. So this is one of the defect in the product. They are the smooth depression of the surfaces of casting. These are usually occurs near the ingates. So shrinkage defect, metal shrinks as the solidify if this is not compensated by providing the risers. So defect due to improper mold drying and core baking. A layer of moisture collected under the impervious layers of mold paint will cause sand and paint scrap and pills with the result that casting shows sand washes, scab, blow holes. Oil sand cores if over baked are not strong enough to resist the flow of molten metal and causes defect. Are sand washes rough surface undersized holes. Oil sand core if under baked absorbs moisture from atmosphere or green sand mold causes the defect such as core sand wash, core blow, blow holes. Defect caused by molten metal. Cold shot and misrun it is the defect in which discontinuity is formed in casting due to imperfect fusion of two strings of metal in the mold. This appears like a seam or a crack. It is common in thin section of the casting. So causes for this one is misrun occurs when molten metal does not fill the cavity properly in sufficient molten metal supplies. So what are the remedies to remove this defect caused by the molten metal is improper, so improve the gating design. Use proper pouring temperatures. Defect due to faulty heat treatment. Cold initial heating operation may cause cracking of brittle casting, careless stacking of casting while they are in semi-plastic state at this heat treatment. Temperature tends to distort. Fast cooling rates may develop cracks in the casting. So next defect is the defect due to cast metal. Hard spots occurs in gray iron casting having insufficient silicon content. Hard spots make machining of the casting difficult. So last one is the defect occurring during fattling. So defective casting may result from carelessness during the fattling operation. Example sand and scale not properly removed from casting surface to be machined later on. Sand not properly removed from cavity where oil is to be circulated. Distorted casting not properly straightened. So these are the some references. Three references are provided for this casting defect. Thank you.