piston working

1. Carbon-carbon commercial products
• High temperature heat exchangers
• IC engine piston
• Clutch plate
• Furnace fixturing
• Heat shields
• Heating elements
• Springs
• fan blades – used to circulate the atmospheric air in heat treatment
furnaces
• Hot press mold
• Bolt and nut
• Crucible for semiconductor
• Arms and hands for robots
• Pantograph sliding plate
• Thermocouple protection tubes
• Charging devises and work piece supports – for metal hardening

2. Piston Functions
• It transmits the force due to gas pressure inside the cylinder to the crankshaft
through the connecting rod.
• It compresses the gas during the compression stroke.
• It seals the inside portion of the cylinder from the crankcase by means of
piston rings.
• It takes the side thrust resulting from obliquity of the connecting rod.
• It dissipates large amount of heat from the combustion chamber to the
cylinder wall.

3. The design requirements for the piston are as follows:
• It should have sufficient strength to withstand the force due to combustion
of fuel and also the inertia forces due to reciprocating parts.
• It should have sufficient rigidity to withstand thermal and mechanical
distortions.
• It should have adequate capacity to dissipate the heat from the crown to the
cylinder wall through the piston rings and the skirt.
• It should have minimum weight to reduce the inertia force due to
reciprocating motion.
• It should form an efficient seal to prevent leakage of flue gases from
combustion chamber to the crankcase past the piston. It should also prevent
leakage of lubricating oil into the combustion chamber past the piston.
• It should have sufficient bearing area to take the side thrust and prevent
undue wear.
• It should result in noiseless operation.
• It should provide adequate support for the piston pin, which connects the
small end of the connecting rod.

4. Aluminum disadvantages
• The strength and stiffness of aluminum rapidly decrease above 180°c;
the melting temperature of aluminum is approximately 600°c; and the
coefficient of thermal expansion of aluminum is large.
• Wear strength is less.
Cast Iron disadvantages
• Density is high.
• Thermal conductivity is less.
• A piston should last for the entire lifetime of the vehicle if the operating
conditions are nominal (normal lubrication, regular maintenance of the
engine, no excessive load, no excessive temperature). In normal operating
conditions a piston should last at least 300000 km going up to 500000 km or
more.

5. Requirement of Material Properties
• High thermal conductivity – temperature gradient is less.
• Low density- reduces weight and inertia forces.
• High strength-thickness of head is less.
• High wear strength.
• Low coefficient of thermal expansion- less clearance provided.
Carbon-carbon composite
1) Has Negligible coefficient of thermal expansion- low piston to cylinder wall clearance-
piston rings and skirts are unnecessary - reduces friction-mechanical efficiency
increases.
2) It maintains strength at elevated temperature - operate at high temperatures and
pressures - greater resistance to structural damage due to over-heating, lean air fuel
mixture condition(greater fuel economy and lower exhaust gas emissions, and with
greater reliability at high power output levels) and detonation.
3) Has high emittance and high thermal conductivity – more heat dissipated to cylinder
wall and cooling system – thermal efficiency increases.
4) lighter than conventional pistons-produce cascading effects-reduce the weight of
other reciprocating components such as the crankshaft, connecting rods, flywheels,
and balances-improving specific engine performance.

6. Clutch plate
Functions of Clutch:
• To transmit power from engine to drivetrain.
• Smooth transmission.
• Protects drivetrain from engine jerks.
• Silent operation by reducing vibration due to drive operation.
• To remove the speed difference between engine and drivetrain by slip
action.
• It delivers the power to wheels via gearbox without stopping during gear
change.
• To allow the engagement or disengagement of gear when the vehicle is
stationary and the engine is running.

7. Requirements of clutch plate material
• Low wear and tear characteristics.
• High durability.
• High and stable friction coefficient.
• High compressive strength.
• Low tensile strength.
• No ductility.
• Materials should resistant to the environment (moisture and dust)
• Material should possess good thermal properties, high thermal
conductivity, high heat capacity and with-stand high temperature
• Material should withstand high contact pressure.

8. Carbon-carbon as clutch material
• High directional strength – multidirectional loading withstand
• Low density-low inertia force.
• Low coefficient thermal expansion-low deformation.
• Porosity can controlled by manufacturing process and constituent
properties-frictional and wear properties.
• High specific stiffness.
• High thermal stability.
• low moisture absorption.
• high strength to weight ratio.
Applications of clutch:
1.Automobile Use – Heavy vehicles, four-wheelers such as cars, trucks,
buses, Two-wheelers, mopeds, scooters, bikes.
2.Industrial Use – Metal stamping, Pressworking, Packing machines, Indexing
tables, Assembling machines, Printing machines, Conveyor belts, Pumps,
Gear drives.

9. Energy losses in a typical internal combustion engine