Grey Iron Castings – A short history

Grey Iron Castings – A short history

Cast or Grey Iron is easily the earliest cast iron products made in China around the 5th century BC. The first few applications of cast iron were simple pots, weapons, ploughshares and shot. And further between 9th and 4th centuries BC, man developed malleable iron casting. It is believed that the Chinese shared their cast iron process all along the Silk Road. However, Western Europeans had little, if no understanding of iron casting process until the 15th century AD. Artisans made use of the casting process to good effect for making heavy cannons for the British Royal Navy, on the orders of Henry VIII.

It was in 1707 that a British man named Abraham Darby made early inroads into the technique of making cast iron pots with thinner walls. The same technique went into making cast iron cookware, with other manufacturers making cast iron shields and several body armour parts. Iron castings soon became popular through the mid-1700s.

The great inventor, James Watt, in the 1770s, invented an atmospheric steam engine, an improvement over the Thomas Newcomen’s model. Watt’s steam engine made grey iron casting easier than before and the parts manufactured had greater accuracy and better strength.

Before the advent of steel, grey iron castings became a popular material as structural components of the bridge. Steel gained popularity in the early 1800s, as it had higher tensile strength and hardness. Grey cast iron, on the other hand, has greater hardness and much higher tensile strength. Because it can prevent fire, grey cast iron was used in the construction of textile mill buildings. Grey cast iron, in particular, can benefit the Textile mills as they were filled with flammable dust and combustible fibres. This leads to manufacturers preferring cast iron for the manufacture of equipment.

Gray Iron castings continue to grow in popularity throughout the last century. In 1967, for instance, grey iron was being cast at nearly two and a half times the volume of other cast metals. The same year, casting capacity of grey iron products increased to 14 million tons of grey iron products.

Today, though grey iron is among the most primitive iron types, it is still cast on a massive scale, proving its utility. The last decade saw a lot of manufacturers increasing the dimensional control with which they can cast grey iron. The quality of thin sections has been greatly improved. Product quality and dimensional control will continue to improve in the future, as manufacturers try out different practices. Manufacturers, in order to make better parts, work on mould surface treatment that effectively replaces post-casting mould blasting methods, leading to faster and economical casting procedures. Today, there are several casting methods employed by manufacturers to strengthen grey iron.