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Ductile Iron Casting: Process, Composition & Advantages

Iron-carbon alloy tweaked by adding magnesium or cerium is what is commonly known as ductile cast iron. Ductile cast iron reacts with sulfur and oxygen while the iron is in the molten stage to create a more ductile alloy.

Cast iron is more of a brittle alloy as compared to ductile cast iron. Little addition of magnesium or cerium allows the ductile cast iron to have a stable alloy structure. The Resulting solidified castings have almost perfect nodules of graphite in it. Ductile cast iron is known for high resistance against impact and fatigue.

How Is The Ductile Cast Iron Made?

Similarly, like any cast iron, ductile cast iron gets its magic from being inside the furnace. The process revolves around incorporating more carbon into the molten iron. The iron in the molten state gets the magic potion of silicon, sulfur, manganese, and oxygen.
This oversimplification of the process might make it look easy but is not this simple in reality. The prime part of the process is adding carbon to iron as much as it can absorb. The composition mix gives the alloy the infamous spherical structure of graphite.

Ductile Iron Advantages

Ductile Iron Casting made out of ductile iron are significantly solid than regular grey iron or cast iron. Tensile strength of grey iron form stands between 20000-60000 psi. However, ductile cast iron can endure as much as double-cast iron’s highest psi strength.

Here are some more advantages –

  1. Ductile cast iron is a more potent form of cast iron. Unlike cast iron that can break easily, ductile cast iron can endure much more.
  2. Nodule formation in ductile cast iron promotes it to bend and not break, unlike the cast iron.
  3. Graphite structure of ductile cast iron works as a dry lubricant to have excellent wear resistance.
  4. Even after being harder to work with than cast iron, ductile cast iron dissipates and dampens vibration, sound, and heat.

Ductile Cast Iron Uses And Application

The ductile cast iron can offer strength, and enhanced wear resistance makes it fit for various uses. Here are some items made from ductile cast iron:

  • Pipe and its fittings
  • Axles
  • Cylinders
  • Crankshafts
  • Disc-brake Calipers
  • Gears
  • Gear Boxes
  • Housing
  • Hydrostatic Barrels
  • Idler’s Arms
  • Large Machinery
  • Military works
  • Piano Harps
  • Spindle support
  • Suspension parts 
  • Truck Axles
  • Valves for high pressure
  • Wheel Hubs
  • Power Transmission Yokes

Difference Between Regular Cast Iron And Ductile Cast Iron

Cast iron is easier and cheaper to cast, and strength is possible with heat treatment. Cast iron has a flakes structure of graphite. On the other hand, ductile cast iron offers higher strength and durability due to the graphite sphere structure.

Conclusion

Ductile iron has the upper hand at durability, given the spherical structure of graphite. Cast iron or grey iron is cheaper but lacks the wear resistance that improves the uses. The most popular type to be used for industrial purposes is the ductile form of cast iron. To know more about the best ductile iron casting manufacturers in India, you can follow http://www.govindsteel.com/.

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All About Investment Casting – Process, Products & Benefits

We have read and learnt about the different types of metal castings in an iron foundry but this blog talks about the versatile form of casting – Investment Casting. Often known as ‘lost-wax’ casting, this process uses an expendable mould to create well-defined and fine surfaces. The precision and versatility of this process make it the number one choice for well-detailed cast objects. The moulds can be used to achieve the desired shape as it can be carved in wax and can be coated. Sure, this process tends to be a little more on the expensive spectrum but the end products can be complex and smooth as opposed to sand casting.

Common Investment Casting Products 

Operational pieces of precision machines are often made via Investment Casting. For example, the fans, camera and other engine parts with complex shapes that need mobility and fine surfaces are made via Investment Casting. It is commonly used for detailed jewellery, vintage and contemporary decor items.

The Investment Casting Process

The basic structure of an Investment Casting Process consists of an expendable pattern of wax mould: a ceramic mould material, and a kiln.

Expendable or Wax Pattern

This wax pattern is an exact replica of the final product one needs. It is filled in with an injection mould made of aluminum or steel. These moulds are usually machined, 3-D printed and hand-carved and owing to this, the process is more expensive than sand casting. Once the injection mold has been created, wax patterns are fast-tracked to allow the cast to solidify.

Pattern assemblies

The second step is to assemble these wax patterns and allow multiple items to be cast together in the tree formation (the casting system). Made from solid wax, tree-like channels are used to carry molten metal to the final product. To ensure efficiency, these structures should be assembled carefully.

Ceramic ‘investment’ mold

On assembling the tree structure, the whole thing is dipped in a ceramic bath and is let to dry, These baths are repeated several times to allow each coat to harden and create a thick mold. The tree is then heated to melt the wax and once removed, the mold is heated to a higher temperature and molten metal is poured inside. This process ceramics dipping and heating is the ‘investment’ of investment casting.

Mold removal

The entire process is let to cool down and once that happens, the ceramic mould is removed to unveil the finished product. Once done, if required, additional finishing or treatment procedures are done.

That is all about investment Casting. Find more about other casting processes and products on www.govindsteel.com. Govind Steel Company Limited is a 55-year-old company that has continually grown to become one of the largest and leading foundries for Grey Iron Castings and Ductile Iron Castings in India, with an installed capacity of 24, 000 MT. Contact Govind Steel today!

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The World of Expendable and Permanent Moulds in Iron Casting

The true pioneers of Industrial Development and the improving standard of living are the foundries – Metal, Iron or Ductile Iron Foundries across the nation. But do we really understand the actual functioning of the same?
Let us debunk this alien concept by understanding the basics of metal castings and different moulds used.

The process where the molten metal is poured into the mould containing a hollow cavity to get any geometrical shape one wants is casting. This process can be further can be divided into two types – Expendable or Semi-permanent Mould and Permanent Mould. Let us find out what are their functions:

Permanent moulds are made of metal with a high melting point over the metal that needs to be cast. The main purpose of using these permanent cores is because they are simple to use and can be reused. Such moulds are generally used for both low-temperature alloys and iron. The castings from this method have thin walls as they are produced with “close tolerance”. Castings made this way are fine-grained and dense with a smoother surface finish. A few common types of permanent castings are:

  • Low-pressure Casting
  • Gravity Casting
  • Die Casting

Semi-permanent moulds are the ones where the cores are expendable and can result in more complex shapes. Usually, sand, plaster and ceramic is used as the core as it allows the possibility of being taken out or broken down to get the casting out. Such moulds are generally bound with a bonding agent that improves its properties and creates complex, intricate castings. A few of the examples are:

  • Sand Casting
  • Plaster Moulding
  • Shell Moulding
  • Ceramic Moulding
  • Investment Casting

Among the foundries in Kolkata famous as industrial casting manufacturers, Govind Steel is one of them. Govind Steel is one of the largest and leading foundries for Grey Iron Castings and Ductile Iron Castings in India. To know more about the same, kindly visit – www.govindsteel.com

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All About Metal Castings – The process, different types and more

In the history of industrial manufacturing techniques, casting is the oldest one. However, modern advancements in technology have led to a host of casting methods and techniques. But before we get into that, here is what casting actually is. It is a process that allows molten metal to be poured in a specially designed mold to take various shapes Read more