Document D2VBQnOZX0mkbzYDnYJwKeLB

FILE NAME Allied Signal Bendix ASB DATE 0000 DOC ASB033 DOCUMENT DESCRIPTION Excerpt from Journal Article 2372 ganics Vehicle tests also showed a reduction in noise levels an unexpected bonus metallics are currently being produced for one domestic vehicle equipped with solid rotors Combinations of organic and metallic pads are being used on a domestic station wagon luxury car and several light truck applications The use of semimetallics has also been expanded to the larger disc brakes currently released for heavy trucks SMALL CAR SOLID ROTOR APPLICATIONS As previously discussed one of the prerequisites of a friction material is its ability to resist wear under various temperatures it will experience in service We also have seen that smaller cars equipped with solid rotors will subject the friction materials to a wider range of temperatures than the mate- rials used on larger cars equipped with ven- tilated rotors It has been our experience that reasonably good predictions of durability life can be made knowing the wear versus tem- perature characteristics of any material The effects which rotor weight and brake configuration have on operating conditions can easily be observed or measured with a Full Brake Dynamometer A procedure which has been used consists of a series of braking cycles at six different initial brake temperatures Each cycle is comprised of 300 stops made from 50 mph at 12 fpsps deceleration The time interval between stops is varied to maintain a constant initial rotor soak temperature The initial rotor soak temperature is increased from 250 to 625 in 75 increments After the 625 cycle a 250 cycle is repeated to establish the low temperature wear rate after severe usage The linings are measured after each cycle and the incremental wear plotted The total rotor wear experienced for the 2400 stop test is also recorded The data illustrated in Figure 7a b and c were accumulated using a 9 diameter solid rotor 0.375 thick weighing 6 lbs Wheel load used was 975 lbs The results clearly show the wear superiority of the metallics over both the Class A and Class B organics While the total rotor wear for both the Class A and Semi- metallic formulations were comparable the Class B materials showed considerably higher opposing surface wear Another inertia dynamometer wear procedure used by some European manufacturers to screen potential friction materials is a series of 4 cycles consisting of 250 snubs from 50 to 17 mph 13 secdeceleration in which the time intervals between applications is held constant at 95 seconds Temperatures generated on this schedule are relatively low usually peaking at about 250 for the brake outlined above As in the previously discuss- P. KWOLEK ed wear versus temperature data the semimetallics showed distinct advantages over both the Class A and Class B organics see Figure CLASS - ORGANIC .100 | ) INNER OUTER ROTOR ----- .000 WEAR j INCHES .080 + + e + + + H INCHES 4 INCHES . 4 + - > > + + WEAR .060+ .060+ WEAR WEAR T e MAXIMUM .040- + MAXIMUM MAXIMUM + MAXIMUM MAXIMUM .020 + + PS + + + - + B 250 ROTOR + ' 400 550 250 TEMPERATURE F Fig Wear dynamometer versus 975 lb temperature inertia wheel load solid rotor CLASS ORGANIC INNER | 100 OUTER .008 ROTOR .008 WEAR | .080 + + # ' 4 | INCHES INCHES > + + + + r WEAR .060 + - + + + + + + WEAR WEAR + + o + C4 + + 4 .040f + + et et + S MAXIMUM MAXIMUM MAXIMUM MAXIMUM ns a. mY B 250 400 550 250 ROTOR TEMPERATURE F Fig Wear versus temperature inertia dynamometer 975 lb wheel load solid rotor FRICTION MATERIALS SEMI- METALLIC 100 | INNER OUTER ----- ROTOR .000 WEAR INCHES oBot + 6 .S + + + + > INCHES INCHES + + + + oa + t WEAR .060f a WEAR + 4 + + WEAR + + + + a r + q MAXIMUM .040 + < * + ' + + 4F MAXIMUM MAXIMUM t + + + - + + q MAXIMUM 4 MAXIMUM .020 er 4 * + + + + . L + + + + + + + 7 , a nk ceed 4 B 250 400 550 250 ROTOR TEMPERATURE F 2373 tests The differences between front and rear brake mileage projections are due to the dif- ferences in operating temperatures and lining availability Rear brake operating tempera- tures were approximately 100 below the front brakes thereby drastically improving the wear rates of the Class A organic In the case of the Class B organic and metallics the lower rear brake mileage projections are the result of differences in available lining thickness - - AVERAGE = - - 50,000 MILES - > MINIMUM - -40,000 -40,000 MILES - Fig Wear versus temperature inertia dynamometer 975 lb wheel load solid rotor - 30,000 - - Y .025 INCHES INCHES ( .020 WEAR LINING .015 LINING CLASS B CLASS SEMI -MAXIMUM Yyj - 20,000 MILES - - J Z 4 G _ Gg ; _ LINING D> Y , .010 SUfG O4p re INCREMENTAL _ D -AVERAGE v) Z U; ... INCREMNTAL .005 RR RR ~~ RR e d A INCREMENTAL ... INCREMENTAL At CLASS ... A CLASS B SEMI 2 4 4 Fig Mileage projections 2500 mile durability test 1973 sedan 2800 lb G.V.W. Fig Incremental lining wear inertia dynamometer simulation of 2800 lb G.V.W. sedan running low temperature durability In the introduction front brake tempera- ture profiles were outlined Figure 2 for a durability test of a vehicle equipped with solid rotors having a brake test weight of 2800 lbs Tests conducted on Class A Class B organics and metallics using this vehicle procedure have repeatedly verified that metallics offer distinct improve- ments in lining life The results Illustrated in Figure 9 confirm the incremental wear rates previously found in full brake dynamometer The particular brake system evaluated utilized front brakes lined with pads 0.475 thick while the rear brakes had pads which were 0.185 thick It is interesting to note that similar tests on larger cars equipped with ventilated rotors rarely show life pro- jections over 30,000 miles Significant reductions ir noise levels were noted when metallics were compared to the Class B organics While specific noise hunts detected brake noise ratings as low as 7 for the metallicts he Class B organics showed unacceptable noise ratings as low as 4 see SAE J1060 Further improve- . scsanesineasieeyen dl TON A Rn 2374 | J. P. KWOLEK ment in noise rating levels were achieved when typical U.S. type insulators were added to the back of the steel shoes A series of vehicle tests were initiated over a year ago in Europe in which a new semi metallic formulation was installed on vehicles subjected to three different types of duty and were compared to a typical O.E. organic lining 1. Taxi cabs having automatic and standard transmissions 2. Rental cars 3. Business travelers described as country driving The estimated annual driving ranges from 12,500 miles 20,000 km for rental cars to 25,000 miles 40,000 km for taxi cabs and business travelers The results tabulated below Table 1 indicate the metallics reduced lining wear rates significansthlowy- ing 250 to 430 improvement With respect to rotor wear the lic offered similar advantages over organic see Table 2 metalthe Class B SUMMARY The performance and wear advantages of metallic linings over conventional organic types have previously been established More recent development has made them more comparable for initial friction and low temperature or initial wear characteristics The high temperature wear capacity of metallic linings enhances their potential for usage 031 smaller cars with solid rotor brakes Actual vehicle comparisons have shown substantial improvements over Class B type organics for projected lining life rotor life and noise characteristics under a variety of usage conditions The gains in lining and rotor life offered by metallics would appear to make them a most viable and cost effective candidate for use on small cars with solid rotor brakes and relative small lining pad areas REFERENCES 1. F. William Aldrich Metallics A New Type of Friction Material SAE Paper 710591 June 7-11 1971 2. G. R. Wynne Development of Police Car Brake Standards SAE Paper 750397 Feb. 24-28 1975 3. Seong Kwan Rhee & John P. Kwolek U.S. Patent 3,835,118 Sept. 10 1974 Table 1 - Lining Wear Rates 1000 Km Class B Organic 0.E. Semi Metallies Taxi Cabs Automatic Manual 6.5 1.5 4.0 1.5 Car Rentals 1.5 0.5 Business Travelers 1.5 0.5 Table 2 - Rctor Wear Rates 10,000 Km Class B Organic O.E. Semi Metallics Taxi Cabs Automatic Manual 0.57 0.02 0.33 0.02 Car Rentals 0.12 0.06 Business Travelers 0.10 0.04 es oatOe /