What is Piston in Simple terms | How Piston made?

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Piston –

A piston is considered one of the most essential parts of a reciprocating engine as it helps convert the chemical energy obtained by fuel combustion into useful mechanical power. The purpose of the piston is to provide a means of conveying the expansion of the gases to the crankshaft, via connecting rod, without loss of gas from above and oil from below. 

Why Does Engine Knocking Occur?

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Why Does Engine Knocking Occur

During normal combustion, the air-fuel mixture in the combustion chamber starts burning from the spark plug as soon as the sparking takes place. The mixture burns smoothly from beginning to end, providing an even and powerful thrust to the piston. The pressure inside the cylinder increases evenly. As soon as the sparking takes place, a wall of flame spreads out in all directions from the spark. It travels rapidly outward through the mixture until all the charge is burned. 

Definition- 

Under certain conditions, part of the air-fuel mixture explodes before the flame wall reaches it. The temperature of the last part of the mixture increases as the flame progresses. If the temperature reaches the critical point, the last part of the mixture will explode before the flame reaches it. This causes a sudden increase in pressure which imposes a sudden heavy load on the piston that is almost like a hammer blow. 

Knocking and Detonation- 

It should be noted that knocking and detonation are synonymous terms with the same meaning. Detonation is the name given to the sudden and violent knocking experienced inside the engine cylinder. detonation is not pre-ignition. If the detonation is allowed to continue for a long time it may overheat the cylinder and spark plug so as to ignite the charge even before the sparking, this will cause pre-ignition. Thus, detonation follows the spark while pre-ignition precedes it.