The preparation of a sand mould is a crucial step in sand casting, a widely used metal casting process. Here’s a step-by-step guide to making a sand mould:
Materials Required:
1. Pattern (Wood, Metal, or Plastic replica of the desired casting)
2. Molding Sand (Mixture of silica sand, clay, and moisture)
3. Flask (Two-part box: Cope – top half, Drag – bottom half)
4. Parting Powder (To prevent sticking between cope and drag)
5. Risers & Gates (For molten metal flow and venting)
6. Rammer & Strike-off Bar (For compacting and leveling sand)
7. Vent Rod (To create gas escape paths)
—
Steps in Sand Mould Preparation:
# 1. Pattern Placement
– Place the pattern on a flat molding board inside the drag (bottom flask).
– Apply parting powder to prevent sticking.
# 2. Filling the Drag with Sand
– Fill the drag with molding sand around the pattern.
– Compact the sand using a rammer for uniform density.
– Strike off excess sand with a bar for a smooth surface.
.jpg)
# 3. Inverting & Preparing the Cope
– Flip the drag upside down.
– Place the cope (top flask) over it.
– Add sprue pins for pouring and risers for venting.
.jpg)
# 4. Filling & Compacting the Cope
– Fill the cope with molding sand and ram it properly.
– Remove sprue pins carefully to form pouring channels.
# 5. Separating Cope & Drag
– Carefully separate both flasks.
– Remove the pattern gently to leave a cavity.
# 6. Finishing & Assembly
– Cut gates and runners for molten metal flow.
– Repair any damaged edges in the mould cavity.
– Reassemble cope and drag, ensuring proper alignment.
# 7. Pouring Molten Metal
– Secure the mould with weights/clamps.
– Pour molten metal into the sprue until risers fill up.
—
Types of Moulding Sand:
1. Green Sand (Moist clay-bonded sand) – Most common
2. Dry Sand (Baked for higher strength)
3. Loam Sand (Clay-rich for large castings)
4. Facing Sand (High-refractor