Wednesday, August 24, 2016

SHELL MOULD CASTING-

INTRODUCTION

  • Shell mold casting is a popular method for the manufacturing of casting products. It is an expandable mold casting.
  • In this a hot pattern is used and the sand will be filled upon the hot pattern.
  • The sand will occupy the shape of the pattern. And pattern will be created
  • In this process the sand that is covered with thermosetting resin is used to form the mold.
  • The shell made by sand and resin will be thin walled and hardened.
  • Shell mold is generally used to create small and medium size casting for which the high precision is required, but as per the requirement heavy castings can also be done by this method.
  • In shell molding method pattern and sand both can be reused and this causes higher productivity.
  • It is an effective metal casting process in the field of manufacturing as it provides many advantages than any other process.
  • A large range of complex parts can be casted by shell mold casting.
  • In this method the component of ferrous, non-ferrous and alloy materials can be used.
  • The difference between sand casting and shell mold casting is that in sand casting metal is poured into the sand mold while in this method sand and thermosetting resin is used to create a thin wall or shell.


PROCESS:-

  1. In the shell mold casting first the shell mold cavity is to be created in which the molten metal is poured.
  2. To create the thin walled shell mold a pattern of desired product is required.
  3. The sand will be filled upon the pattern so that the sand occupy the shape of the pattern.
  4. After that the pattern will be inverted or made upside down so that the excess sand is removed and the pattern will have the mold in it.
  5. The sand is mixed with resin and the pattern will be hot, this create a strong, though and thin walled shell mold.
  6. When the thermosets are cured i.e. the mold is ready, the pattern is removed and we will get the mold or part of mold.
  7. Generally the mold will be in several part and we will get the pattern after combining those parts. So after combining the parts of the mold together the cavity will be formed.
  8. The molten metal is poured in this cavity and the metal is allowed to solidify by providing the appropriate solidification time.
  9. After solidification the material is took out of the mold. This can be done by breaking out the sand mold.
  10. Although, it provides a good surface finish, but if there is a requirement another surface finishing operations can be performed on the specimen.


ADVANTAGES:-

  • This process requires less no. of labor or manpower.
  • The process is simple and higher rate of production can be achieved.
  • Higher accuracy is the main advantage offered by this casting process.
  • Shell mold casting provides better surface finish than sand casting.
  • Automation for the whole process can be provided and the productivity can be further increased.

APPLICATION:-

    Gears, cylindrical composhell mold casting provides lots of application for the industrial pupose. Few of them are given below as an example-nents, cylinder head, shafts, valve bodies etc.

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