CERAMIC DISC BRAKESHANEESH JAMES S8 ME8 ROLL NO: 20
Todays technology is in need for speed, also safety as well, for that deceleration is needed engines of max efficiency for maintaining the speed & brakes of latest technology is used. Brake system are required to stop the vehicle within the smallest possible distance. By converting kinetic energy into heat energy which is dissipated to atmosphere.
Brakes must be strong enough to stop the vehicle within the possible distance in an emergency. (safety) Brakes should have good antifade characteristics also on constant prolonged application its effectiveness should not decrease.
STOPPING DISTANCE OF A VEHICAL DEPENDS
Condition of road surface. Condition of tyre thread. Coefficient of friction b/w tyre thread & road surface. Coefficient of friction b/w brake disc/drum & brake pad. Braking force applied by the driver.
TYPES OF BRAKESPurpose Construction Method of Extra actuation braking effortService brakes Parking brakes Drum brakes Disc brakes Mechanical brakes Hydraulic brakes Electric brakes Air brakes Servo brakes Power operated brake
DISC BRAKE- CONSTRUCTION
COMPARISON b/w CERAMIC DISC BRAKES AND CONVENTIONAL DISC BRAKES
Grey cast iron disc is heavy which reduces acceralation, uses more fuel and has high gyroscopic effect. Ceramic disc brake weight less than carbon/carbon disc but have same frictional values, used in Formula1 racing cars etc. CDB good at wet conditions but carbon/ carbon disc fails in wet conditions.
Weight CDB are 61% lighter, reduces 20kg of car, apart we can save the fuel, resulting in better mileage. Improve the shock absorber and unsprung masses. We can add more safety features instead of the current weight.
MANUFACTURE OF CERAMIC DISC BRAKEIn earlier days disc brakes were made from conventional brittle ceramic material. DIAMLER CHRYSLER made carbon fibre reinforce brake disc to avoid the brittle property. First they used long carbon fibres the short which increased the efficiency. short carbon fibres + carbon powder + resin mix(at1000 c, sintering) = stable carbon frame work.
After cooling ground like wood brake disc obtains its shape. Add silicon to the required shape and insert in the furnace for the second time, pores in the carbon frame work absorb the silicon melts. Matrix carbon reinforce the liquid silicon after cooling grey disc brake is ready. Resins : thermo plastics resins and thermo setting resins .
COATING OF CERAMIC ON CONVENTIONAL BRAKE DISCS
FRENO Ltd-used metal matrix composite for disc, an alloy of aluminum for lightness and silicon carbides for strength. The ceramic additive made the disc highly abrasive and gave a low unstable coeff of friction. SULZER METCO Ltd- special ceramic coating, developed thermal spray technology as well as manufacturing plasma surface.
Ceramic phasing requires special metallic friction pad, deposit a layer on the brake disc. This coupling provides wear resistance, high and stable coefficient at friction. The coated matrix composite discs were first used on high performance motor cycles were reduced gyroscopic effect ha the additional advantage of making the cycles turn .
PORSCHE CERAMIC DISC BRAKES (PCCB)
Porsche has developed new high performance disc brakes, (PCCB). CDB with the involute cooling ducts for an efficient cooling. Offers braking response, fading stability, weight & service life. Does not require substantial pedal forces or any technical assistance.
PCCB ensures maximum deceleration from without any particular pressure on the brake pedal. It response under wet condition. New braking linings cannot absorb water. Cross drilled brake discs help to optimize response of the brakes also in wet weather. The process involves of carbon powder, resins and carbon fibres in a furnace to about 1700 c is a high vacuum process
ADVANTAGES50% lighter than metal disc brakes reduces 20kg of car. In the case of train 36 disc brakes saving amount to 6 tons . Apart from saving fuel also reduce unsprung masses with a further improvement of shock absorber response & behavior. High frictional values in deceleration process Porsche- 100 to 0 km in 3 sec. Daewoos Nexia- 100 to 0 km in 4 sec.
Brake temperature. Resistance up to 2000 c . Still runs after 300000 km need not change CDB. No wear, maintenance free and heat and rust resistant even under high oxygen concn. Heavy commercial can be braked safely over long distance without maintenance.
FORMULA1- in mid 90s French sports car specialist Venturi. Porsche 911 turbo- with a top speed of 305 km/h and acceleration from rest to 100 km/h in 4.2s. Its engine 3.6 L with 420 hp max torque 560 Nm is still running with PCCB. 911GT2- and Mercedes Benzs futuristic vision GST is going to reinforce CDB .
High initial cost and high cost of production. As the advantages listed above we can hope CDB will work out to be cheaper in the future.
CDB due to its advantages over the conventional brake disc are going to be the brake disc for cars in the future. With the success of Porsche turbo car, many other racing cars and commercial vehicles are going to implement CDB in cars.
AUTOMOTIVE MECHANICS CROUSE/ANGLIN www.porsche.com www.diamlerchrysler.com www.mercedesbenz.com www.howstuffworks.com