(Metals can be melted and reshaped easily because they exist in a liquid state when they are formed.)
SAND CASTING.
Sand casting is a way of making metal objects. It uses sand as a mold to shape the molten metal. This process is very common, with over 70% of metal castings made this way.
To make the mold, sand is mixed with a bonding agent like clay and water. This creates a strong and moldable mixture. A special type of sand called Petrabond is often used.
DIE CASTING
Die casting is a way to make metal objects by forcing melted metal into a very strong mold. The mold is made from hardened steel and works like a cookie cutter. Most die castings are made from metals that aren't iron, like zinc, copper, aluminum, and magnesium. There are special machines to handle different types of metal. Die casting is used for making lots of the same object, because the equipment is expensive. It's a simple process, so it's good for making many small to medium-sized parts. The metal objects made this way have a nice smooth surface and are all the same size. There are different ways to do die casting, but they all.
GRAVITY DIE CASTING.
This type of casting uses gravity to pour the melted metal into the mold.
PRESSURE DIE CASTING.
This type of casting uses a strong press to push the melted metal into the mold. It uses a hot or cold chamber, depending on the metal being used. The pressure makes the final object more precise and detailed.
INDUSTRIAL DIE CASTING.
This type of casting uses more than two mold pieces to make the object. Normal die casting only uses two pieces, which limits the shapes you can make. But by adding more pieces, you can create more complex, three-dimensional objects.
LOST WAX CASTING.
This type of casting uses a wax model to make a metal object. The wax model is often made of pewter, silver, gold, brass, or bronze. The process is very detailed and allows artists to make very intricate objects. The steps for casting small pieces are usually the same, but the process can vary between different workshops. This type of casting is also called "investment casting" in modern factories. Sometimes the mold is destroyed to remove the finished object. This is called "lost mould casting" or "waste wax casting."
EXTRUSION.
Extrusion is like squeezing a tube of toothpaste. You push a material through a mold to make it into a specific shape. The material can be hot or cold.
Metals, plastics, clay, and even food can be extruded. You can't make a hollow shape with a simple flat mold. Instead, the mold has to have a special shape that supports the inside of the object. The mold changes shape as the material goes through it, to make the final shape.
(Plastic is really easy to reshape because it can be melted and turned back into a solid at a lower temperature compared to other materials.)
INJECTION MOULDING.
Injection molding is like squeezing toothpaste into a mold. You heat up the material and force it into a mold that has the shape you want. The material cools and hardens in the mold.
Injection molding is used to make all sorts of things, from tiny parts to big car parts. The molds are usually made of metal, like steel or aluminum. They are very precisely made to make the parts perfect.
Sometimes, 3D printing can be used to make molds for injection molding. This is especially helpful for simple molds.
ROTATIONAL MOULDING.
Rotational molding is a process where a hollow mold is filled with powdered plastic. The mold is then slowly rotated in different directions, causing the plastic to melt and stick to the mold's walls. The constant rotation keeps the plastic even and prevents sagging. This method allows for hollow objects with thick walls, which wasn't possible with other molding techniques. Rotational molding has become more popular in recent years thanks to advancements in plastic materials and better control of the process.
EXTRUSION.
It's like injection molding, but instead of using a powerful hydraulic ram to force the melted plastic into a mold, the plastic is continuously pushed through a die, creating a long, consistent shape. Think of squeezing toothpaste out of a tube – that's similar to how extrusion works.
COMPRESSION MOULDING.
Compression molding is a popular way to make things out of special plastics that become hard and strong when heated (like those used in countertops).
This method is great for making strong, complex shapes, especially those that need fiberglass for extra strength. It's also very cost-effective and doesn't waste much material, which is good for using expensive plastics.
RESIN AND GRP MOULDING.
GRP (Glass Reinforced Plastic) isn't quite a "reforming" process like melting and reshaping plastic. Instead, it starts with a liquid plastic (resin) that gets mixed with tiny glass fibers. The mixture then hardens and sets, becoming solid. So, while it's not exactly reshaping, it's still a way to use plastic to create things, and the glass fibers make it very strong.
3D PRINTING.
3D printing is like building with tiny bits of melted plastic. It starts with nothing, and then a machine adds layers of melted plastic on top of each other to create a 3D shape. It's a super new way to use plastic, and it's even able to make things out of metal, food, and even body parts!