Manufacturers of automotives have key objective that is to ensure the highest possible reliability and durability of the engine and its parts like piston pins. The piston is an element installed in the crankshaft assembly, which is responsible to convert thermal energy into mechanical. The piston head creates a rotary part of the combustion chamber. The piston grooves are designed in a way to hold piston rings that are used for sealing the cylinder working space.
The major use of piston is to conquest the piston head-space pressure force using the piston head. This force is transferred to the piston, piston pin, through the connecting rod and to the crankshaft. The piston construction has to-
- Pass on the heat of the hot piston head to the cooled cylinder walls
- Guide the piston in the cylinder sleeve
- Take over the pressure on the cylinder bearing surface
- Make minimum possible friction losses
- Ensure low lubricating oil consumption by the engine
Manufacturers use distinct range of materials to cast pistons for automotive internal combustion engine-
- Cast iron
- Alluminium alloys
- Alloy steels
Apart from these materials, manufacturers also use aluminium-silicon and aluminium-copper alloys. Aluminium alloys are unique by good formability during casting and machine cutting. However, there is a drawback of these alloys- a large thermal expansion coefficient, low strength, and low hardness.
Cast iron pistons are less manufactured and used. You can see them in low-speed self-ignition engines. They possess good slide properties, retain great mechanical properties at elevated temperatures, and a small thermal expansion.
Due to high strength indices and low thermal expansion, manufacturers have started making pistons with alloy steels.
There are some common reasons behind the failure of the pistons –
- Lower sparking plug heat factor
- Too lean air-fuel mixture
- Valve leakage
- Insufficient valve clearance
- Glowing piston head, valve, cylinder head, and sparking plug burning leftover
- Petrol contamination
- High engine temperature
Engine overheating occurs due to the malfunctioning of the cooling system, a faulty water pump, fouling, a broken V-belt, and incorrect system. In air cooled engines, overheating occurs because of deposits and fouling inside the cylinder.
Cracks occur due to the excessive loads. Incorrect course of combustion process, incorrect starting of the cold engine, using wrong piston pins.
For more details on defects and failures of engine piston pins, you can browse online articles. You can even ask experts here in comments and wait for their reply.
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Compression rings are among piston pins used as metal sealers that fit between cylinder walls and pistons in internal combustion engines. Each of the rings fits inside the groove around the piston’s outer diameter.