Document qNG6pKqOyKnGKoaKKozDVQ05

FILE NAME Allied Signal Bendix ASB DATE 1974 Sept 10 DOC ASB202 DOCUMENT DESCRIPTION US Patent - Sponge Iron Friction Material United States Patent 19 Rhee et al 11 3,835,118 45 Sept. 10 1974 54 175 SPONGE IRON FRICTION MATERIAL Inventors Seong Kwan Rhee Southfield Mich John P. Kwolek Troy NY Assignee The Bendix Corporation South Bend Ind Filed Appi No May 1973 360,255 U.S CI Int Ch Field of Search 260.38 51 29 106/36 106 240 260 DIG 34 C08g 51 08 Hoe de Ta 250 DIG 19 260.38 260.38 (oe! References Cited UNIHEESTATES UNIHESTATES UNIHEESTATES PATENTS 801 962 TN 87 : DUNES Crangu^ Spokes In J06 36 7.43.9 ; 3.492,262 3.492,262 3.492,262 3/1969 5/1972 Aldrich bee Griffith Grifith Grifith wenn ee anes cages 106.36 ~ 106.36 Primary Examiner Lieberman Assistant Examiner R. Michl Attorney Agent or Firm H. McCormick Jr ; William N. Antonis 1571 ABSTRACT A metallic friction material for use in a vehicle brake as a friction lining or pad The metallic fuction material utilizes the abrasive surface produced in coarse sponge iron to provide a high coefficient of friction and good wear resistance up to 250 to com pliment the coefficient of friction and wear resistance capable of being produced by the interaction of metalin an ceramic powders steel fibers rubber particles particles and graphite above 2507 7 Claims 2 Drawing Figures he PATENTSEEPD1074 101074 3,835,118 FIG 2 3.835.118 I 2 SPONGE IRON FRICTION MATERIAL BACKGROUND OF THE INVENTION a high coefficient of friction upon initial engagement with a corresponding brake member These and other objects will become apparent from , Friction materials consisting of graphite metallic ce- reading this specification and viewing the drawings ramic and rubber powders held together by a thermosetting resin have been used as brake pads in braking systems to provide a uniform coefficient of friction without excessive fade Such a brake lining material is fully described in S. Pat No. 3,434,998 incorporated herein by reference The Department of Transportation of the L.S. Gov- BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is perspective view of a friction pad for use in a brake assembly FIG 2 is an enlarged view taken along line 2 o2f FIG 1 illustrating the relationship of the compositional ingredients in the friction pad ernment has proposed that acceptable safe braking dis- tances be reduced It has been determined that if an ore gani friction material such as that disclosed in US DETAILED DESCRIPTION OF THE PREFERRED COMPOSITION application Ser No 309 incorporated herein hy Throughout this specification the terms metallic reference could be modified to provide a high coeffi- powder and ceramic powder are used to denote a mate cient of friction immediately upon engagement of the rial having a nominal size which will pass through a No wear pads with a mating brake surface the proposed 80 mesh screen and consist of at least 85 percent of a standards could be met Frictional modifiers having base material with the balance being mainly oxides of higher coefficient of friction were tried however un 20 the base material Similarly the term sponge iron de- desirable side effects such as noise poor wear fade notes a material having a nominal size 85 percent of grooving in the mating surfaces and reduced structural which will pass through a No. 20 mesh screen yet will strength resulted be retained on an 80 mesh screen and consist of at least 90 percent metallic iron SUMMARY OF THE INVENTION The brake pad 12 for a shoe 14 shown in FIG is We have discovered a composition for a semi- metallic friction material wherein coarse sponge iron constructed of a metallic material whose principal ingredients are sponge iron graphite and modifiers particles are utilized as frictional modifier The abra- held together by a thermosetting phenolic resin which sive surface of the sponge iron will provide a brake lin- 10 is then cured under heat and pressure to form a ing with a high coefficient of friction upon initial en- biended rigid mass 16 as illustrated in FIG 2. Whil gagement with a corresponding braking surface Be disc brake pads are not illustrated test results indicate cause the sponge from partycks are unannealed and the same advantages car bu found when this material yourse yourse initial burrash les temperature temperature wear on the bred on disc brakes inction pad will be reduced The regular surface of The sponge iron particles 38 are irregular in shape the coarse sponge tron which includes minute pir with a surface having pin hole voids therein The holes will compliment the noise attenuating compos sponge iron is produced by a method known as the nent in the metallic friction material to essentially Sicurin process In this process powdered magnetite minate squeal associated during a frictional engage iron ore carbon coke and lime are charged in layers men Since the sponge iron particles have a nominal 40 into covered crucibles These ingredients are heated in size of between 201 to 80 mesh which tend to rupture kilns until reduction is complete After cooling the ander transverse loads steel fibers in proportioned iron produced which is removed will have a physical rell bonship with the spongy iron particles are added to appearance of a round porous cake about 10 inches in the metallic friction material to provide structural diameter and 2-2inches thick The reduced sponge unity for the brake lining 45. cakes are then crushed and disintegrated into particles is therefore an object of this invention to provide Hoeganaes Spong Iron Corporation Riverton N.J serv metalli hase material with a friction modifier produces sponge iron particles that are unannealed consisting of coarse sponge iron particles to increase cold friction and reduce wear when used as a brake designated M 20,80 having a nominal size which can vary from 20 mesh to 80 mesh have proven satisfactory pad for brake pads These sponge iron particles have an It is another object of this invention to provide a metallic base material for a brake pad having abrasive surface sufficient to provide a high coefficient of friction upon initial engagement of the pad 12 with coarse sponge iron particle- as the principle compo a corresponding braking surface yet are large enough nent to compliment noise reducing ingredients therein to resist abrasive wear at low operating temperatures in attenuating sounds created upon the brake pad en- as thereby reducing low temperature wear gaging a corresponding brake member A typical composition for the metallic brake It is still a further object of this invention to provide pad 12 is as follows a metallic material having coarse sponge iron par- ticles uniformly distributed therein to provide a high All coefficient of friction at low temperatures and steel fi- hers therein to provide structural unity when the semi- Metalho powders copper fron & Zine metallic material is used as a brake pad Sponge Iron Particles is still a further object of this invention to produce produce Ceramic Powders rallimanie mullita magnesium exude mariumi sulfate metallic friction material consisting of a mixture aluminum ouvir and ree, ns Cm ee of metallic and ceramic powders coarse sponge iron sibya non eviden eviden Steel Ener graphite rubber particles and steel fibers rigidly post- Rah nares - tioned in resin matrix for use in brake pad having having toranbee Volume Percent = Volume Percent ; tr V o 10 to 1 . 21-14 " Mu . I ar 14 Cw 3,835,118 3 4 Phenolic resin hinder -Continued Volume Percent 100 = Volume = Percent 10 41 metallics compared to organics when operating at temperatures below 325 Average driving seldom re- sults in temperatures above 325 and is generally con- sidered to generate brake temperatures of around S 250 Thus the wear rate of any potentially commer cial friction material must be equivalent to organic ma- terials at these lower operating temperatures The use The ingredients are mixed together and formed into of coarse sponge iron particles has shown a significant a desired shape Then the mixture is placed in an oven reduction in both the 250 and 325 wear levels where the resin is cured to hold the other ingredients 10 thereby improving the chances for commercial accep- in a fixed position with respect to each other After cur- tance ing the resin the material is shaped into a finished prod- uct such as the brake pad 12. The relationship of the various ingredients are illustrated in FIG 2 as follows As previously discussed the proposed Department of Transportation reduction in acceptable safe brake stopping distances requires that the brake systems re- sponge iron particles 18. graphite particles 20 rubber 15 main balanced throughout the test This requires a fric- particles 22 ceramic powders 24 steel fibers 26 iron tion material which will exhibit the same friction levels powder 28 and resin 30 throughout the test While conventional metallic Brake pads manufactured according to a formula as materials exhibit better friction stability than most or- represented above were compared with brake pads of ganics throughout the test one problem was found with a conventional metallic friction composition 20 conventional metallic materials that was low ini- wherein the metallic powder constituted about 20 by volume of the total mixture with the following results tial burnished) friction As a result conventional metallic materials were unable to meet the pre- Morn ot St 2018 Sem Metallic Metallic Nomi Metalk Spongi Iron 250 es? Nb Coeficient Coefficient Coefficient of Friction 3759 074 U6 4754 qe 15 ... Wty 250 F 38 10 Wear in 10 Vetor Vetor 306 Stups 3252F ... k 475 < 50 10 10 The importance of providing an initially high coefficient for the brake pads can readily be realized from burnished stopping distances proposed by the Department of Transportation The use of coarse sponge iron the following formula through which the effective brak- 25 particles in metallics have demonstrated signifi25 ing distance on a level roadway may be approximated cant improvement in initial burnished friction d = 17.30 17.30 which will be required if metallic materials are to be considered for commercial usage where Further upon investigating the metallic mate- = braking distance in feet 1 = initial speed miles per hour 40 rial it was determined that the sponge iron will compliment the rubber particles therein to attenuate noise or J = coefficient of friction between friction members squeal caused upon engagement of the brake pad with such as brake pad and drum a corresponding member Assuming that the coefficient of friction will remain It is assumed that the voids in the sponge iron parti- substantially uniform the period of time required to 45 cles act as acoustical absorbers by breaking up the path bring a vehicle to a stop will be proportionally reduced through which sounds may travel As an example assume identical vehicles wherein The over transverse structural unity of the brake pads may be varied by the amount of steel fiber 26 used one has brake pads constructed of a standard semi- in the mixture However due to the disparity in price metallic material and the other of a metallic mate- 50 between steel fiber and sponge iron about 6 times for rial with sponge iron particles and both are traveling at 60 miles per hour the effective braking distance will be mass production a volumetric change in steel fiber content will usually be adjusted by a proportional change as follows in the quantity of sponge iron particles d = 60< ^ 0.32 = 3600= 375 Thus we have developed a metallic composi- 55 tion wherein the structural characteristics are en- sponge iron = 30 0.38 = 3600 11.4 = 306 Thus the vehicle with the brake pads having a semi- hanced by the use of sponge iron particles when used as a friction pad in a braking system metallic material with sponge iron particles therein ex- We claim hibits a shorter effective braking distance which will 1. A metallic base material for use in a vehicle conform to the proposed stopping distance of the Department of Transportation brake as a friction lining said material consisting of a mixture of The wear resistance of conventional metallics metallic powder selected from a group consisting of are equivalent to organic materials between 350 and iron copper zinc and mixtures thereof from <te 450 and are superior to organics at temperatures 65 30 percent of the total mixture } above 450 However one of the major obstacles to sponge iron particles from 10 to 40 percent by vol- the accpetance of metallics as a friction material ume of the total mixture said particles having a has been the poorer wear resistance of the semi- nominal size which can vary from 20 to 80 mesh