The most widely used casting process, sand casting, uses disposable sand moulds to shape complex steel pieces that can be manufactured from practically any alloy. Sand casting has a poor production rate since the sand mould must be destroyed in order to remove the item, known as the casting. A furnace, steel, pattern, and sand mould are all used in the sand casting process. The steel is melted in the furnace, then ladled and put into the hollow space of the sand mould, which is shaped using the pattern. The solidified casting can be removed after the sand mould separates along a parting line. The steps of this methodology are detailed in the next section.
The mould is created in a flask, which is a metal or wooden frame with no fixed top or bottom. The flask is known by many names depending on its location in the moulding structure: drag – lower moulding flask; cope – upper moulding flask; cheek – intermediate moulding flask used in 3 piece moulding.
- Pattern: This is a copy of the final product to be manufactured. The design is used to create the mould hollow space.
- The separating line between the two moulding flasks that make up the mould is called the parting line.
- Molding sand: Sand that binds tightly while maintaining permeability to air and gases. It’s made up of the right quantities of silica sand, clay, and moisture.
- Facing sand: A little amount of carbonaceous material that is placed on the internal floor of the mould hollow space to give the castings a raised floor end.
- Core: A separate section of the mould made of sand and baked, which is utilised to make apertures and various created cavities in the castings.
- Core prints: If a hole or hollow space is required in a casting, it is created via the middle. The mildew at the sand impressions is where this middle is located. These forecasts are in the middle.
- Pouring basin: On the top of the mould, a little funnel formed a hollow chamber into which the molten steel is poured.
- Sprue: The conduit through which molten steel is transported from the pouring basin to the mould hollow space. It often regulates the flow of steel into the mould.
- The molten steel is transferred from the sprue to the gate by a tube called a runner.
- Gate: A route through which molten steel enters the hollow region of the mould.
- Chaplets are utilised to assist the cores in the mould hollow space in dealing with their own weight and overcoming the metallostatic force.
- Riser: A riser is a reservoir in the mould that acts as a source of liquid steel for the casting during solidification to compensate for shrinkage. Also known as a “feed head.”
- Vent: A small opening in the mould that allows air and gases to escape.
Metal processed by casting
- Sand casting- 60%
- Investment casting-7%
- Die casting-9%
- Permanent casting-11%
- Centrifugal casting-7%
- Shell mold casting-6% .
Sand Mold (Sand Casting)
The sand mildew’s hollow area is created by packing sand around a design, then separating the mould into halves and discarding the pattern.
- Gating and a riser system should also be included in the mould.
- If the casting is to have interior surfaces, a mould should be used to cover the centre. For each element created, a fresh sand mould should be constructed.
Properties of sand mold
It must be sturdy enough to withstand the molten metal’s temperature and weight.
- It must endure the erosive action of the warm metal flowing over it.
- Due to the molten metal’s temperature, it should produce a small amount of gases.
- It should have strong venting capabilities to allow the produced gases to escape completely.
Types of sand molds
Green Sand Molds
Silica grains, clay, and moisture are used to make this product.
- Right now, metal is being poured and the castings are being removed.
- The most common application is for mass production.
Dry Sand Molds
Completely dried in an oven at 150 to 350 degrees Celsius for 8 to 48 hours. Improve your strength.
- Castings ranging in size from medium to large.
- Better dimensional precision and floor end precision.
Skin Dried Molds
Torches are used to dry the skin to a thickness of 15 to 25 mm.
- Pit moulding is a viable option.
- Pouring must be done right away.
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