Moulding and core making

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MOULDING AND CORE MAKING
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PRODUCTION STEPS
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INTRODUCTION

• Moulding and core-making are essential processes
  in foundry operations.
• Moulding involves creating a cavity into which
  molten metal is poured to form a desired shape,
  while core making involves crafting removable
  structures to shape the interior of the casting.

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MOULDING PROCESS

• A Mould is a hollowed-out block that is filled
  with a liquid like plastic, glass, or ceramic raw
  materials. The liquid hardens or sets inside the
  mould, adopting its shape. A mould is the
  counterpart to a cast.
• Assembly of the mould and core pieces to make a
  complete mould, metal then being poured into the
  mould.
• Mould is obtained by pattern in Moulding material
  (sand).
• Mould material should posses refractory
  characteristics and withstand the pouring
  temperature.

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TYPES OF CASTING SAND

• This process is used to create metal products in
  a wide range of shapes and sizes. Over 70 of the
  world's metal castings are produced via the
  sand-casting process. Sand casting is highly
  efficient and cost-effective.
• Green Sand Moulding
• Dry Sand Moulding
• Resin sand molding
• In our company, we are using Green sand Moulding
  and Resin sand Moulding.

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GREEN SAND MOULDING

• Natural sand prepared as a mixture of silica sand
  with 18-30 clay and 6-8 moisture.
• Fine, soft, light and porous.
• The name Green sand employs for damped i.e. it
  contains moisture and the mould made of this sand
  is used immediately to pour the molten metal.
• Easily available and has low cost.

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RESIN SAND MOLDING

• Resin sand is a type of quartz sand that is mixed
  with a resin material.
• The chemical reaction created by the resin helps
  to bind and stiffen the quartz sand to make
  solid, hard and strong molds

• Hot Box Sand with resin with addition of
  Heat(curing ).
• Its not a popular one.
• Cold Box Here catalyst in Gaseous form.
• Interact more, Very fast process, small
  components.
• No Bake Box Here catalyst in Liquid form.
• Its used for all size of component.

Sand resin Curing (polymerization)
Moulding (organic)
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PROPERTIES OF MOULDING SAND

1. Refractoriness The ability of moulding sand to
   withstand high temperatures without breaking down
   or fusing.
2. Permeability Liquid metals cause evolution of
   gases due to their reaction with moulding sand
   ingredients.
3. Collapsibility After solidification of the
   molten metal, the casting is required to be
   removed from the mould.
4. Cohesiveness Moulding sand should be capable of
   withstanding the compressive and erosive force
   exerted by liquid metal while filling the cavity.

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SAND CASTING PROCESS

• 25T Autoloop
• 50T Manual (Larger size)
• 60T Autoloop

25T Autoloop
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CORE MAKING

• Cores are apparatus used to generate hollow
  cavities or internal features which cannot be
  formed using pattern alone in Moulding, cores are
  majorly made using sand, but some processes also
  use permanent cores made of metal.
• Cores are made of clay-free silica sand, which is
  thoroughly mixed with suitable binders, water and
  other ingredients to produce a core mix. This
  core mix is packed into core box that contains a
  cavity of the desired shape.

1. Horizontal core.
2. vertical core.
3. Balanced core.
4. Cover core.
5. Drop core.

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VENTING
In the casting process, the core will be
surrounded by molten metal which will stimulate
gases inside the mold, and it is essential to
provide a venting passage for these gases as if
remain entrapped inside the mold, these gases can
result in casting defects. Therefore, to obtain
good permeability additional venting holes are
made in the cores.
REINFORCEMENT 
Some cores, heavy large cores in particular,
might need additional reinforcement material like
cast iron grids or low-carbon steel wires to
maintain coherence.
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BAKING OF CORES

• Depending on the type of process used, baking of
  sand cores is done in convention oven with
  temperature between 200 C to 250 C (392 F and
  482 F), the heat causes the binder to polymerize.

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CLEANING FINISHING

• After baking, cores are ready for cleaning
  finishing. Following methods are used as per
  requirement
• Trimming of cores involve removing loose pieces
  and other unwanted projections
• Brushing is used to remove loose sand off the
  core with fine wire brush.
• Coating is crucial step for finishing and
  involves coating of cores with refractory
  material to improve heat resistance.
• This step includes either manual or machine
  inspection of the cores for dimensional accuracy.

INSPECTION
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