Manufacturing Processes

Manufacturing Processes

• Production involves transforming a blank or raw material into a finished product by changing its shape, size, and properties through a series of steps called production or manufacturing processes.

Classification of Manufacturing Processes

• Manufacturing processes can be classified into five categories:
  • Shaping processes
  • Machining processes
  • Joining processes
  • Finishing processes
  • Property changing processes

Examples of Manufacturing Processes

• Shaping processes:
  • Casting
  • Forming
• Machining processes:
  • Turning
  • Drilling
  • Milling
• Joining processes:
  • Welding
  • Brazing
  • Soldering
• Finishing processes:
  • Grinding
  • Polishing
• Property changing processes:
  • Annealing
  • Hardening

Casting Process

• Casting is a process of producing metallic parts of desired shape and size by pouring molten metal into a mould cavity, allowing it to solidify, and resulting in a solid casting.

Moulding

• Moulding is a process of making a mould using a pattern, which is a model or replica of the part to be cast.
• Common materials for pattern making include wood, metals like cast iron, brass, and Al alloys.

Overview of Casting Process

• The casting process involves several steps: pattern making and mould making, melting and pouring, solidification and cooling, removal, cleaning, finishing, and inspection.

Pattern and Mould

• A pattern is a replica of the final product, used for preparing the mould cavity, and can be made of wood or metal.
• The mould cavity, which contains molten metal, is essentially a negative of the final product.
• Mould material should possess refractory characteristics and withstand the pouring temperature.

Melting and Pouring

• Several types of furnaces are available for melting metals, and furnace selection depends on the type of metal, maximum temperature required, and the rate and mode of molten metal delivery.
• The gating system should be designed to minimize turbulent flow and erosion of the mould cavity.

Solidification & Cooling

• The properties of the casting significantly depend on the solidification time and cooling rate.
• Shrinkage of casting during cooling should not be restrained by the mould material, otherwise, internal stresses may develop and form cracks in the casting.

Removal, Cleaning, Finishing and Inspection

• After the casting is removed from the mould, it is thoroughly cleaned, and the excess material is removed using a portable grinder.

Sand Casting

• Sand casting is a casting process in which sand moulds are used.
• Sand moulds are prepared in a moulding box or flask made of wood or metal, open at the top and bottom, and made in two parts held in alignment by pins.
• The gating system consists of a pouring basin, sprue, and gate.
• A riser is a passage to permit outflow of molten metal, acting as a reservoir of molten metal to compensate for solidification shrinkage.
• A core is a solid mass used to obtain a hole or recess in the final casting.