Document 0g4DowroonOXNBZzYDqvbaqXb

Prepared for U.S. ENVIRONMENTAL PROTECTION AGENCY Office of Pesticides and Toxic Substances Washington, D.C. GCA-TR-81-32-G Submitted in Partial Fulfillment of Contract No. 68-02-3168 Technical Service Area 3 Work Assignment Nos. 7 and 18 EPA Project Officer t James Bulman \ ASBESTOS SUBSTITUTE PERFORMANCE ANALYSIS Final Report May 1981 Prepared by Nancy Krusell David Cogley Ts-"/C} gP-A &/ H .JV ^^ ., /)(,;: GCA CORPORATION GCA/TECHNOLOGY DIVISION Bedford, Massachusetts HWBUI0012927 CONTENTS Figures....................................................... Tables. . .................................................................................... Acknowledgments............................................................................. v 1. Introduction....................... 1 References............................................................ 4 2. Paper Products................................ 5 Introduction................................................................. 5 Flooring Felt ................................ 7 Roofing Felt........................................................................................................... 10 Beater-Add Gaskets............................................................ . 16 Pipeline Wrap..................................... 20 Millboard and Rollboard................................ 23 Commercial Papers .................................... ..... .............................. 30 Electrical Insulation .................................................................................... 34 Specialty Papers..................................................................... 38 Beverage and Pharmaceutical Filters ..... ............................ 46 Cost Comparison....................................................... 50 Current Trends........................................................ .... . ................................. 53 Conclusion, ..................................................................... . 57 References. . . ................................................................. 60 3. Friction Materials.......................................... .... . . .......................................... 67 Asbestos Product. ............................................................. '....... 67 Substitute Products ............................ ...... ............................ 77 Cost Comparison.......................................................................... 93 Current Trends....................................................................................'. . . . 94 Conclusion................................................... 96 References................................ 99 4. Asbestos Cement Pipe ................................................... 103 Asbestos Product. ............................................................................................. 103 Substitute Product. ...................................... 110 Cost Comparison .......... ........................... 128 Current Trends......................................'.......................................... .... 130 Conclusion..................................... 130 References.......................................................................... 132 5. Asbestos-Cement Sheet. . '...........................................................................................135 Asbestos Product................... ,................................................. ........................... 135 Substitute Products ... ........................................................................... 138 Cost Comparison....................... 150 Current Trends. ........................................................ 151 Conclusion.............................................. 153 References......................................................................................................................155 iii ! HWBUI0012928 CONTENTS (continued) 6. Flooring Products................................................ . .......................................... Asbestos Product . . 7 . . ......................................... Substitute Product . ................... . ........................ ....... Cost Comparison....................... Current Trends . Conclusion................................................... ................................. . . . . . References ...................................... .......... ................... 7. Gaskets and Packings ...... ................................................................. Asbestos Product . .......................................................................... Substitute Product ........................ Cost Comparison........................ Current Trends ....................................................... Conclusion ........................ References....................................................... 8. Paints, Coatings, and Sealants......................................' . ......................... .Asbestos Product ................................................... ' Substitute Products.............................................. Cost Comparison. ............................................................. ....... Conclusion........................................................................................................... References ...................................................................... . ............................ 9. Reinforced Plastics . ............................ Asbestos Product............................ .... .................................................. .... . Substitute Product....................... Cost Comparison..................................................................... Current Trends....................................................... Conclusion............................................................ References .................................................................................... t................... 10. Textiles. ............................................................................... Asbestos Product ................................................................................... Substitute Product................................ Cost Comparison........................ Current Trends................................ Conclusion ....................................................... References..................................... 11. Miscellaneous Uses. .................................................................. ....... Introduction . ......................................... Drilling Muds (Fluids) ............................................................................... Cost Comparison....................................................... Current Trends ...................... Conclusion................................................................. Shotgun Shell Base Wads............................................................................... Asphalt/Asbestos Cement............................................................................... Foundry Sands. ....................................................... Sprayed-On Insulation....................... Artificial Fireplace Ashes and Artificial Snows........................ References ....................................................... 12. Results, Discussion and Conclusion. . . ..................................................... Results and Discussion ............................................................................... Conclusion ........................................................................................................... 158 158 162 165 165 165 166 168 168 173 192 194 195 196 201 201 207 217 219 221 224 224 226 234 234 238 240 242 242 247 257 260 260 262 265 265 265 271 273 274 274 274 276 277 278 279 282 282 289 iv SECTION 3 FRICTION MATERIALS ASBESTOS PRODUCT Special Qualities All products containing friction materials rely on the coefficient of fric tion between mating surfaces to transmit or stop motion. Brakes convert kinetic energy into heat, absorb the heat, and gradually dissipate it into the atmos phere. Brakes consist of two parts, the rotor which is connected to the wheel, and the stator on which the friction material is mounted. Clutches transfer kinetic energy from a rotating crankshaft to the transmission and wheels. Both b-rakes and clutches may operate wet or dry. In dry systems, the heat is conduc ted to the air and surrounding structure while wet systems operate within oil or another fluid* which absorbs the heat to. maintain temperatures below 200C (392F). The special qualities required by friction materials include: o Possession of the appropriate coefficient of friction for the desired application Ability to withstand the high temperatures generated at friction interfaces Dimensional stability "v.., Strength Durability Lack of abrasive characteristics which could lead to scoring of mated surfaces. Asbestos is used in friction materials because of the properties listed in Table 11. The most important properties are thermal stability, reinforc ing abilities, and relatively high friction. ,, 67 HWBUI0012930 TABLE 11. UNIQUE PROPERTIES OF'ASBESTOS APPLICABLE TO FRICTION MATE* 1 14---s* Properties Comments Fibrous form Flexibility contributes to forming character^ Fibers interlace and interlock, enhancing stri Flexibility reduces wear at friction interfao Fine fiber diameter' Provides strong reinforcing characteristics B of the large number of fibers per unit weight' High tensile strength Provides strength and durability to friction products. Temperature resistance Unaffected by T < 500C. Stable for short pei of time at T around 1000C. Able to withstanj temperatures generated at friction interfaces. Cost Provides low cost/performance or cost/physical property ratio. Product Composition Friction materials for automotive brakes and clutches are complexc posites of three general types of ingredients: reinforcing fibers, 0 property modifiers, and 0 organic resin binders. 0 Historically, asbestos fibers have been the major constitutent of nearly organic friction materials, so chosen because of their thermal stability tion level, reinforcing properties, availability and relatively low cost, Small quantities of other fiber reinforcement may also be used. Because tos alone does not provide all of the properties required for friction a rials, property modifiers are added to provide various degrees of fricti wear, fade, recovery, noise, and rotor compatibility. A resin binder is to hold materials toegether and contributes to the friction characterise, of the mixture. Table 12 lists common ingredients found in several pate, formulae. Following is a more detailed description of the raw materials in organic friction material. Binders-- In wet mix processing, a viscous material (usually a resole) is use< dry-mix processing, a powdered material (usually a novolac) is used. Pfr and cresylic reins (both synthetic) are the most commonly used binders a1 normally modified with drying oils, rubber, cardai^L, or epoxy. P 68 TABLE 12. as. Copolymers TYPICAL INGREDIENTS USED FOR FRICTION MATERIALS (IN WEIGHT %)9 Asbestosb Sulfur oxide Cardolite0 Resin Barite Rottenstone Other additives A 22 B 11 C 17 D 15 E 15 F 15 G 15 H 15 I 15 J 15 K 13 L 13 H 15 N 15 0 15 P 17 Q 17 R 17 49 2 4 12 12 63 1 2 12 12 54 2 3 12 12 58 2 3 12 12 58 3 13 12 79 1 3 2 69 1 3 10 2 69 15 10 79 1 3 69 1 3 2 10e 55 1 2 9 2 17f - 64 1 3 10 6 l8 15 6 5 40h 69 1 . 3 g 2 10 69 4 10 2 49 4 30 65 4 10 69 4 10 ld ld 191 Acrylonitrile-butadiene copolymer ^Grade 5K chrysotile. cFriction dust made from cashew-nut shell oil (3M tradename dAbundum (600 *) - aluminum oxide. Unidentified friction particle. ^Zinc dust. gParaformaldehyde (curing agent). ^Steel wool. Iron oxide. j Orion fiber. r-\,i,\ V n t f -! ` 5,vlJV 4 -" * ' 69 HWBUI0012932 Fibrous Reinforcements-- / The asbestos normally used in friction material is chrysotile. The/size distribution of asbestos fiber consumed by the friction materials industry in 1978 consisted of chrysotile grades 3 through 8 (predominantly grades/7 and 5) and anthophyllite. A total of 73,800 megagrams (72,975 mej?ic tona)<sworth $22,813,600 Canadian dollars was consumed. Of this, only^OO megatons)was anthophyllite.6,7 Long-fiber asbestos (grades 3, 4, and 5JM-S nsad-tn dry-mix processing and short-fiber asbestos (grades 6 and 7) is used for wet-mix pro cessing. The longer fibers permit the bending of linings from flat to curved segments. Clutch materials contain additional continuous-strand reinforce ments including cotton, asbestos, yam, brass wire, and copper wire. Property Modifiers-- Property modifiers can be classed as nonabrasive and abrasive. Table 13 lists property modifiers and their functions in organic friction materials.. Uses and Applications The primary uses for friction materials are brakes for light- and heavyduty vehicles, aircraft, railcars, and various types of heavy equipment. Clutch facings are another important friction material product. Minor uses include braking mechanisms for bicycles, presses, hoists, lift trucks, mining and drill ing equipment, chain saws, tape recorders, spinning and knitting equipment, typewriters, snowblowers, and washing machines. In addition, many business machines require clutch mechanisms. The primary uses for asbestos-containing friction materials are listed in Table 14. Product Manufacturing Summary Manufacturing "Process-- Production methods and raw materials used in the manufacture of friction materials vary, depending on the intended application of the final product. Organic linings, which must bend, require high resin contents and long fibers. Stiffer, heavy-duty materials with less resin require molding for shape and clutch materials require special fiber-forming methods. Major manufactur ing methods are described below. Linings--Most linings are produced from resin wet-mix by extrusion or in rolling processes. Asbestos and various property modifiers are mixed with liquid.resin at 50C (120F), then binder solvent is added to yield a putty like mass with good wet strength. In the extrusion process, the mix is heated to 90C (195F) and extruded as a flat, pliable sheet.which is dried for 2 hours at 80C (175F). In the rolling process, the partially dried mix is fed between two rolls that align the fibers into flat, pliable "green lining." Linings are then cut to length, formed at 150C (300F), and molded for 4 to 8 hours at 180 to 250C (360 to 480F). The final product is ground to pro-__ duce finished brake linings. 70 HWBUI0012933 o -5 X, CrHO w.J *L333p PO3/3O)o L3p LPPa3UC3O3U. r--po3Eq1 MO-J C>P3OO3>rf, V ; i1 Pp3U3C3qCHOO 5 Ki!. p>33 ;`v M>Pa3O ? *P3qOPH ' 3 /r \ (f \ j^ , \ ! it 1 C'*' <ft \ |/ poc ' J3C3O HP333 PqoOPHH 3 PO3 ,3c p3P33>O3qH wU33 i*UPHO3P3H3 .p3PQP3> *UPq033 *p--u3Ql xOopq3> OO rapEp333o---( pCP3Cc3PH5x CP3qotHHHo p3co 333P3 T0(oC30)l .oo ,iV3-3cli. P333pQ *3P3Oao O3paDOu N*33-/ opPp3oqO3qrf OPPt33i-^H*i^PpV3H3coH)* *'3l|J5hb qE3H3 < *JrCaaZ4O 'SracJi C(o0O CooMI p3qo33H 3 To"31 *n3>HH33 i--3qH1 j PPhU33Q:,`;**pq3E3PH T*3HJ PO3 pCHouqHHD ;> 3?1 3CH/ U CO *TppaP3OC3>HoH3 iUHPo3- H*OO33H TC3OoauJ . *3q2 T3 h33J "oOoCC3a0O TOCq3p.3O. ***Jp3Xo>H333% e3 < 0) O H iH P 3 O*-H M. U H MP UP HS3 V3i O 71 HWBUI0012934 J V<5, i3 Cw<3 H (0 CJ CO 3 g MM O 4J CO H O p 43 rH cd 33 -rto 60 cfl H H Vi rH rH UCU - oCU <1 to 3 eG *rt <-1 rt 33 *> O CO e4 O 4-1 f 3w <$ * *> (0 3>S a 3 M Pi 4-1 CO o 43 rH 33 *rt 60 CO iH Pi rH Pi O CO C 0) *rt i--t S rt 33 O C| ^ 3f O1 4J 9 3M C a> cd 6 l CO 0) p cd CO T3 <D CO P 0) H rH G -H X^ .O Gg 60 o PP Xcd G cd co 0) rH rt 33 O 6o 43 3 CO > > eo CO 43 G3 P3 < !ao CO <D G rH P Sn & 60 43 P GG <43 1o H p .fi pH o G *rl pH co o H G 4-1 CO # rH G rH o P rl H G o O 4-1 60 M cd a a 0) p G V P p H 33 43 G CO GG CO G GG o m p cu P H rs CO iH &, P G UG CM Gp G fP 43 3 CO P PG Pu 4-1 OS3 a CO 0) M 4J a) !3 CO rH t-H O 4-1 H P g cd pM co CO cro G O pH * r-- H P cd Sin-X CO G 0) G to p. 8 o o H 43 CO G G 43 td P a) 43 rt w (0 P 3 CO X GG G !5 G 33 43 CO o rH 43 rt CO P- G 3G 43 3 H Cd CO *H Pt O p p H G cr CH G oP Pa !3 CO a a) CO O o G o TJ O * 43 to G a) co O a 43 rl G Gp G 33 G 60 O H o H P o a o G O >3 co O 4M CO & rt U P H o cd cn O u CO a) O /-- H 33 H I G 4-1 P in H CO rH u~> rH P3 p o CO wo E-t P a cd G o P 9\ G G G o G o fcr. O H /> M a; o O p a M o o PQco <3 x o 0) 00 O rH si* o rO v-/ o ao oo rl rl O P P 4-1 o cp G O o c r> 3 o o 43 o iH /-s G 'O- eG oX Go O G* O 43 o W G rM |xi cd m P id m 43 PM P Oo P rt o po a ip CO o o rl o a) P P u o CU 143 H o G o 3 >43 > (0 G o H o a, o P X rl cr o CO op P H rl G p vO 6 a GP 'O m IP X CO CO H <4-4 vO 3 33 H o P 4M n 33 WCO G CN o cd o p cd G CJ o a) 60 P P H o V 43 4J P 43 X U 60 4M rn 43 G fo 60 S3 o o rH G rQ a o *H m O 43 PS co i--1 CO H G p PC 43 o P St 43 CO CO i-3 9 +oj 3 TOP3 PU HWBUI0012935 Linings for heavy-duty use are produced by a dry-mix process. Asbestos, modifiers, and resin are mixed and formed into 60 x 90 cm (24 x 35 inches), briquets that are pressed for 3 to 10 minutes at 140 to 160C (340 to 375F), and cured in molds for 4 to 8 hours at 220 to 280C (425 to 540F). The brake linings are finished after grinding. Disk pads--A dry-mix is prepared as for heavy-duty linings. The mix is formed into briquets at room temperature and 27.6 to 41.4 MPa (4000 to 6000 psi). The briquets are pressed at 160 to 180C (320 to 355F) and 27; 6 to 55.2 MPa (4000 to 8000 psi) for 5 to 15 minutes and are then cured at 220 to 300C (430 to 570F) for 4 to 8 hours. Grinding produces the final product. Blocks--Asbesto^blocks are prepared by a dry-mix process. Briquets are formed at 10.3 to 17.2 MPa (1500 to 2500 psi) and heated to 90C (195F) for 15 to 30 minutes to reduce blistering during hot processing. Blocks are formed at 130 to 150C (265 to 300F) and 13.5 to 20.7 MPa (2000 to 3000 psi) for 10 to 30 minutes. The blocks are then cut and ground to shape. Final curing takes place in confined or unconfined form. After grinding, drilling, and chamferring, the block is finished. Clutch materials--The primary concern in the manufacturing of clutch mate rials is the placement of the wire reinforcement within the matrix. A drymix is used in molding without wire or molding around wire preforms. Another method is to prepare a wet mix and run a wire through the viscous material. This material can be woven after drying. The surface is ground to final shape after pressing and curing. Woven bands--Woven bands for heavy-duty.uses are produced by a process that begins with asbestos cord (which may be reinforced with wire) being passed through a wet-mix to pick up resin and modifiers. The saturated cord is then woven into tapes that pass through heated rolls to partially cure the resin. The material can be post-cured at 160C (320F) to remain as a flexible roll lining or post-cured at 280 to 230C (355 to 445F) to form rigid segments. Such materials are found in large band brakes used to control large machinery. Name and Number of Manufacturers-- There are 27 major manufacfcurars--of asbestos-bearing fri.C-t.io.EU-materials-.- listed in Table, ll/^Both large diversified companies such as Raybestos-Manhattan 3nd small single product companies are included in this list. The first eight companies listed in this table accounted for 75 to 85 percent of the total esti mated sales of asbestos-containing friction materials in 1975, a pattern con sistent with the industry's historical trend. From 1954 to 1967, the eight larger companies together accounted for 86 to 91 percent of the industry's value of shipments. Production Volumes-- Table 16 giy^p the consumption of asbestos in friction products for the years- 1969 to Q9rJ Figures for production volumes were not available, but a breakdown of the vAli^e of asbestos-bearing friction materials projected to 1979 from 1972 values gd!\fen by Meylan is provided in Table 17. ___ 1978 198 I TatP /T HWBUI0012936 T3 w a <y a> o U H vl <0 in 4 H JS I >OtJ -X-Hi Hov> 0) Q c> a i? o ssoo r- O O O s O r-i O 00 ^ so n n or I a> d (0 M O 0) 4e> * o a to J= o u c *4 Hi 41 Hi t>d H hHSUI CB flj O si b Ma i *h SswlH 3o' O 41 e T3 <9 e (9 u s o -i g H> T3 ato Hi O co a3 Hi Vi to a js a. to >t-t *H Q) O fll *d C CO WHO o >* c ai c h u 4 2 rfl bq ttf - >01 >o* ac0 Hi-* Q> ,C ^o 4>> *3j 41 " .dai u nj n 3 li h o H h to W ST U In HUM U H a w O *H au V) [*- 3& (fl o r r-< C H *H > T3 J2 r-j o O. w UH ij a > o Hi *fi 3 00 a> g !-- jj to Cvj OO Hflii CO uo a<s c en eo> 3 uouo 60 3 sn iC H (Of" *H-i y > 60 O ca H b) <o Hn HN Hi C (0 O 3 *ri Cd M Hi O T3 O. I if) tC-1 *3a uU u u*<Ha fC- *cH a *h w 03 e o Ou - -y4 o o > pq ?3 in u aO 'Jj ll gm XC s & mcfl oo r -H o c >E C(0 U0 75 HWBUI0012938 J0 TABLE 16. ASBESTOS CONSUMPTION BY THE FRICTION MATERIALS INDUSTRY 3* (THOUSAND METRIC TONS) 1969 64 1970 60 1971 62 1972 66 1973 .1974 72 73 1975 60 1976 58 1977 83 19(>8 I 77 i1 ! 00 ls> // TABLE 17. VALUE OF ASBESTOS FRICTION MATERIAL SHIPMENTS (IN MILLIONS OF 1979 DOLLARS)3 Final product Total product shipments, including interplant transfers Brake linings Woven, containing asbestos yarn, tape or cloth Molded, including all nonwoven types Disk brake pads $ 23.2 257.0 32.3 Clutch facings Woven, containing asbestos yarn, tape or cloth Molded, including all nonwoven types Other 45.2 110.2 8.2 Total asbestos friction material $476.1 Projected from Meylan et al.1 using January 1980 Engineering and Mining Journal cost index factors. 76 HWBUI0012939 SUBSTITUTE PRODUCTS Methodology Search Strategy-- Twenty of the largest United States asbestos product manufacturers, as listed in Median,10 were investigated to determine which friction materials are being produced. These manufacturers were questioned regarding both asbes tos and substitute materials. Relevant trade associations were also contacted. Several sources in the literature were recommended by the above contacts. The section in tfeesaEncyclopedia of Chemical Technology entitled Brake Linings and Clutch Faciifgs8 was very useful in the writing of this section. Summary of Contacts-- The following individuals and companies provided useful information con cerning friction materials. Robert A. Clifton U.S. Bureau of Mines 2401 E St., NW Washington, DC 20241 Robert Curran, Chief Engineer Spring Division Borg-Warner Corporation 700 South 25th Ave. Bellwood, IL 60104 George Bason Director of Advertising and Public Relations Abex Corporation 530 Fifth Avenue New York, NH 10036 Jack Reynolds Johns-Manville Corp. Ken-Caryl Ranch Denver, CO 80217 Leon Kopyt Mass Transit Systems Corp. Suite 1428 Suburban Station Building Philadelphia, PA 19103 Walter Nichols Sales Representative Midland-Ross Corporation 55 Public Square Cleveland, OH 44113 Eugene Connor, National Sales Manager Johns-Manville Corp. Ken-Caryl Ranch Denver, CO 80217 Joe Minsky P.T. Brake Lining Co., Inc. 18 Shepard St. Lawrence, MA 01842 Mr. Baltz, President Baltz Co., Inc. 28 Robinson Rd. Lexington, MA 02173 Raybestos-Manhattan, Inc. 100 Oakview Drive Trumbull, CN 06611 Kevin Peppard Asst. Dir. of Business Planning Automotive Group Bendix Corporation \ V 40 North Bendix Dr. P.0. Box 4001 Stmth^nd,_IN.--4'6-6'34'* Mr. Anderson, Sales Mgr. Royal Industries, Inc. Brake Products Division Stewarts Lane Danville, KY 40422 77 J ! { HWBUI0012940 >'' ' ' Edward W. Drislane Executive Director Jack Payton, Shop Superintendent Friction Products Co. 922 Lake Rd. . Medina, OH 44256 Standee Industries, Inc. P.0. Box 87 Houston, TX 77001 Griffin Wheel Co. (Division of Amsted Industries, Inc.) 200 W. Monroe St. Chicago, IL 60606 Terry Blaine Spring Division Borg-Warner Corporation 700 South 25th Ave. Bellwood, IL 60104 Bill Shine, Sales Administrator Auto Specialties Mfg. Co. P.0. Box 8 St. Joseph, MI 49085 Donna Craven, Customer Service Scandura, Inc. P.0. Box 949 1801 N. Tryon St. Charlotte, NC 28231 Brassbestos Mfg. Corp. 45 E. 5th St. . Paterson, NJ 07524 Paul Biondo Auto Friction Corp. 652 Andover St. Lawrence, MA 01842 Robert Randolf Gatke Corp. E. Winona Ave. Warwaw, IN 46580 Lasco Brake Products Corp., LTD 26th & Magnolia Sts. Oakland, CA 94607 Mr. - Apollogene. Sales Representative MGM Brakes 21800 Greenfield St. Detroit, MI 48236 Carlisle Corporation 511 Watnut St. Cincinnati, OH 45202 Thiokal Corporation/Chemical Div. P.0. Box 1296 Trenton, NJ 08607 Earl Fygert Sales Manager National Friction Products Corp. 1441 Holland St. Logansport, IN 46947 Mr. Sleeth * H.K. Porter Co., Inc. ThermoId Division 315 Porter Bldg. Pittsburgh, PA 15219 Mr. Montgomery, General Manager Stanley Belting Co. (Distributors for Reddaway Mfg. Co.) 28 Euclid Ave. Neward, NJ 07.105 Wheeling Brake Block Mfg. Co. 3602 Jacob St. Wheeling, WV 26003 Reginald Kelley, General Sales Manager Force Control Industries, Inc. 3656 Dixie Highway Hamilton, OH 45014 78 1 t HWBUI0012941 VOLrU is ^H6l b&jytM ^ (q<l 4 h^b7))%jj ^ **$-. ifi*G)&y &sk> y ^ ^rfaJr a>|?e^ w ^04^X\x i^& <?^) <3AJL jpf4o<w6 ^ -~^hjtji/t%- )Yv_ *fjL <g^^4A4^/jlW HWBUI0012942 $A Roy Huckabee, Sales Representative Nuturn Co. (formerly World / Bestos Co.) 1112 S. 25th St. New Castle, IN 47362 Fiber Substitutes Most companies have pursued the'' development of both fiber and product substitutes to insure asbestos-free products at the earliest possible date. Both naturally Occurring and synthetic materials have been evaluated as sub stitutes to asbestos in friction products. Evaluations are made on the basis of friction stability, wears effect on opposing surfaces and noise.. In many cases, direct substitution of the alternatives mentioned here has resulted in poor friction levels, fiction instability, roughness, structural failure, | f (Vincreas noise, mati; surface and/or front to rear brake im- ich that rnplete refo cessary a%, a^further course of losing inasbestos fil very brittle, have no sur ace adsorptivi and are diffi- cult to handle. Whereas asbestos iundies open during mixing to entrap the friction modifiers and resin, giving a consistenrplx, nonasbestos fibers often spring back and their low tack leads to weal&structures. Asbestos has a high, stable friction leveL. good lAdsorptivity for strength and wear resis tance and does not contribute^tb'nofs^j substitute fibers generally show greater frictional instability, little or no surface adsorptivity, and/or a significant contribution both to the noise factor and to mating-surface degradation.36 iT-j-n'p'^n hf^aVi'lr ror a semlmata I 1 i r. for e-gamp 1 prea/pr* ptrct^garB-with-so-l-i4-rotor-slA,,Lthis ean-valsn caurte brnfce irfaces". Many factors such as these influence the special quality attributes of asbestos versus substitute materials in this area .'W Special Qiiaiities and Product Composition-- These are given for the following materials, which have been proposed as substitutes for asbestos in various friction materials. Some have beep suc cessful in replacing organic friction materials for some applications. Table 18 summarizes the advantages and potential problems with these materials as com pared to asbestos. Glass fiber--The overall strength of glass fiber is lower than that of asbestos but' strong enough for friction material applications. However, it is I not a viable substitute because it melts at the temperatures reached at braking interfaces even in depths below the operating surface, causing fade. It also looses its fibrous form in high shear mixing, has low wear resistance, and I wears aggressively. M"--Compared toasbestos, the overall strength of steel ij lower and its cost is higher. rThe material hardness of^steel wool can result' I fn~scoring of"thg~TBafing~surface. Wear debris can cause severe damage to the Brakes using steel fibers are more noisy than asbestos-containii I I 79 &. * HWBUI0012943 TABLE 18. REINF0RC1 FIBERS FDR FRICTION MATERIALS' Fiber AdvantSgSs Potential problems Asbestos High strength and modulus Thermal stability Infusible Good wear Also acts as filler Linked to health problems Aramid (Kevlar) High strength and modulus Thermal stability Non-aggressive wear characteristics Needs special attention in mixing Steel Wool Adequate strength and modulus Thermal stability \ Noisy* jiigh densit^ Corrosion- .) Low cold friction^/ Costly^____-- Glass Adequate strength and modulus Osdv&tfaJoJb /tJL&Mt/ar- Melts at very high tempera tures causing fade Loses fiber form in high shear mixing Molding spring back Low wear resistance Aggressive wear characteristics Cermets-Sintered High thermal stability Materials High cost, insufficient wear resistance, high thermal conductivity ..Silicon Nitride Long service life, high .thermal conductivity Expensive, heavy NorOloid Fibers Highly insulating, flameretardant, nonmelting Carbon Fibers High strength, very high modulus Infusible High thermal stability Low density Loses fiber form in mixing Costly Low temperature and impact strengths Mineral Wool Inexpensive Low strength, brittle Semi-metallic Materials Thermal stability Excellent wear resistance Expensive Vermiculite High temperature strength Valvar Y. Loken, Industrial Fibers Div., E.I. duPont de Nemours & Co., Inc., Wilmington, DE,4^ in combination with GCA literature reviews. m m m m u m v B B II B is I K HWBUI0012944 I tC. IV Mineral wool2 k--'The overall strength of mineral wool is very low and brittle to the extent of limiting mixing processes. I Potassium titanate fibers7--The National Aeronautical and Space Admini stration (NASA) has investigated new friction materials and their applica tions outside the space program. As part of this effort an improved friction material was developed that utilized potassium titanate fibers with the DuPont tradename FYBEX for lightweight cars and trucks. However, unfavorable toxi cological effects and other market considerations caused DuPont to withdraw FYBEX from the market. Silicon nitride37--This material was used for the brake pads in proto types of the Concorde. It has a longer service life than asbestos and higher thermal conductivity (desirable in this application) but is more expensive and heavier than the carbon composites eventually adopted. Noroloid fibers36--Noroloid fibers wereilnvented by the Carborundum Company in the late 1960s. Made from novola$( (phenol-formaldehyde) resin, the fibers are compatible with many resin and rubber matrices. The manufac turer claims the highly insulating, flame-retardant and nonmelting fibers are finding increased acceptance as a replacement for asbestos in, among other applications, friction materials. Carbon fibe48 The main^properties of carbon fibers are good but still mewhat inferior to asbesto A major consideration is cost, which is a yeat-deal higher- than for~asbestos. It is more efficient than asbestos under igh service temperature conditions, but heat flow is uneven and the tensile and impact strengths are relatively low. It has high thermal stability and low density, making it especially attractive for aircraft brakes. Abex Cor poration of New York, NY took out a patent for a nearly pure carbon article for replacement of brakes or clutch disks in 1971. Abex makes tiger ccmpSs tion brake shoes containing fiber, rubber, resinous material and fillers.12 ,'i-H Vermiculite--A British patent was recently issued for a vermiculitebased'brake lining. The composition of this product is given in Table 19. Although not produced in volume, it serves as an example of continuing research and development activity aimed a^ replacing asbestos in brake linings TABLE 19. VERMICULITE-BASED BRAKE LINING FORIRELATION3 9 Material / % Composition 4% solution of rubber Calcium carbonate X Barium sulphate / \ Synthetic rubber's \ Iron oxide, zinc oxide\ chromium oxfde V 40 15 15 20 10 81 HWBUI0012945 h> v*A k^cA) ^ i^la^Af (\i(i\jtty) <W c*sv*^****g y^ h^cv^ &r liWA I HWBUI0012946 Delaminated vermiculite is used in friction materials commercially avail able throughout Europe. They maintain strength at high temperatures, are com patible with phenolic resins, require little attention in manufacturing methods, and may be used with asbestos to help reduce asbestos content.37 Aramid fibers--Kevlar aramid fiber is made of an infusible aromatic poly amide polymer. Inert fillers are then selected on thfe basis of thermal and wear characteristics, with less concern about other properties due to Kevlar's efficient strengthening. One brake mix tested consisted of: 50 percent wollastonite, 20 percent barium sulfate, 15 percent dry phenolic resin, 15 per cent cashew friction particles, strengthened with different forms of Kevlar at the 5 percent level. Kevlar can be bought as cut fiber, which can be pro cessed in a mixer to any length. Kevlar can also come as a continuous fila ment whch gives the highest strength conversion, or as a pulp which is more fibrillated and shorter than cut fiber and can be readily processed into fric tion paper.1*0 Aramid fibers are being researched fot-Nuse in high performance dry clutch facings, automatic transmissions and asbestos-free brakes. Kevlar, for exam ple, has high tensile strength and is reported to be five times stronger than steel on a weight basis.1*0 Composites have good resistance to external abra sion, high frictional stability, excellent durability,and much better high temperature properties than common organic fibers. They are used in disk brake pads with wear levels between asbestos and semimetallics, and are now in experimental use in drum brake linings and wet friction papers. They do not score mating surfaces and can presently be found in manual transmissions for Mercedes, Audi and Porsche.51 However, the fibers are not easily dispersed in mixing as they tend to clump together. JTE. I. duPonFlre"~Nemovrc * Cn ., .af^WilmingEDttr DE tuodu^f*0 *e'irVaTL.aranii.d fibers7 This appears to be a promis ing candidate for reinforcement of friction materials. Other37--Various other fibers have been used in phenolic binders, such as aluminosilicates (wollastonite). However, all have drawbacks and none is yet as good as asbestos, especially for higher-temperature applications such as disk brake pads. Product Substitutes Special Qualities and Product Composition-- The following materials are currently under development and/or produc tion as direct substitutes for asbestos friction products. Some of these presently occupy a significant share of the friction materials market for some applications. Carbon compositesV-These materials are made of carbon fiber - reinforced carbon matrix composites. The fibers are produced by graphitization of organic or pitch fibers by techniques resulting in parallel alignment of carbon chains with fiber length providing maximum tensile strength. In one description, the article is wound up from one or more filaments, resin: soaked. and then who1e^part~4sjj.ltimate1y carbonized by sintering./The carbonized reinforcing filaments have a greaTerstrenf than the carbonized resin binder. These V filaments can be .facing which has used for st; no filamen alone and to back an all-carbon friction 82 > i k k y T.;v HWBUI0012947 <r& fcrir t4(St&f y<}JU^A <f\.> Jzsv' sircz*< i sv~vUs HWBUI0012948 Semlmetallics--The major constituent of nearly all semimetAllies is iron powder in co-nj unction with a small "amount uf sLuerl firber. Property modifiers are added to provide desired performance characteristics and a resin binder is added to hold the materials together. Nonabrasive modifiers including cardolite, ground rubber, carbon black, petroleum coke flour, and natural and syn thetic graphite are added to control friction, improve wear, and reduce noise. Abrasive modifiers such as alumina, silicon carbide, and kyanite are also used to control friction. A typical semimetallic friction formula may include metallic powder, sponge iron particles, ceramic powder, steel fiber, rubber particles, graphite powder, and phenolic resin. Because of the ferrous nature of the product, rust inhibitors may be added. C'uX'x/uaJL Semimetallics were first introduced in the 1960s, primarily to meet heavy-duty disk brake and extreme duty truck block applications, although they operate satisfactorily against the ventilated cast-iron rotors in the smaller brakes of downsized cars and against the solid rotors found in the lighter brakes of new front wheel drive vehicles. They rely on steel fiber and powders metallurgy techniques for reinforcement without asbestos. Semlmetallics aref \ stable to temperatures of 400C (750F) and exhibit excellent wear resistance*/ f"'\ CermefcjS8 ;2 4--Cermet friction materials are composed of metal bonded cera mic, The metal matrix may be copper or iron. Typical formulae are presented in Table,20./X Cermets have extremely high thermal stability. Wear -rcoistance is not sufficient for automobile use and cost is high. They are used extensively in aircraft and high-speed train brakes. Both carbon fiber and cermet mater ials are stable to 700C (1290F). One problem is high thermal conductivity, which can excessively heat hydraulic brake fluid causing erratic performance.41 This problem may be avoided by proper design.49 Other--Raybestos-Manhattan Inc. manufactures RAYFLEX, a nonasbestos friction material for use in oil-cooled transmissions and brake applications in large, off-the-road vehicles.48 Uses and Applications-- Semimetallic, cermet, and carbon composite materials are used in the j) friction materials industry as substitutes for asbestos^ 4v iJr'p /}( The Friction Materials Standards Institute polled^it^memp^rshftp [ep.rly in 1980 to obtain information on the use of nonasbestos 1Results of this survey are presented in Tables 21 and 22. However, the data does not specify the exact type of nonasbestos lining used nor the actual prevalence of the asbestos substitute. In other cases, such as for police cars and taxis, nonasbestos brake linings were a buyer option, with actual usage depending on the number of orders placed. a *In some years, semimetallics were being phased in and were not included on all models. 83 HWBUI0012949 TABLE 20. CERMET FRICTION MATERIALS CM m CO o pH vO m CO sf 00 00 O 4-- 00 00 oo 00 co CM sr vO 00 00 vO CM CM pH vO ON 00 H vO vO ON pH 00 ON CM CM oo co 00 CM r^. m vO CM o CO rH rH oo pH rH vO 4 vO CO 00 co Cs. vO CO 4 ON CM lO rH rH co CO o *4 sf 00 rH pH ON ON vO CM CM 4 h. CM lA vO CO vO CO CO O 4 rH 1^. CO VO vO CM 4 4 CO rH CO 4 44 VO CM CM CM vO vO 4 Om r^. CO n* vO 00 4 rH O rH 00 00 VO m -3 o rH CM CO ON ON m CM CO o\ m 4* 4 o ON ON vO m rH rH mm m ON Ov sr 4 vO vO ON ON in H CM 4 4 4 o n* ON vO in rH rH in m u-i ON 4 3- o> rH rH ON On m CM CM \o co 4 4 vO CM ON 4 pH *4* vO CO rH vO CO pH vO n* CO co 00 ON CM CM in m in vO sr o rH H CM CM m CM CO rH rH CO H 00 CM CM m m o vO sr o rH rH r** r-. vO CM CO 00 pH ao ON CM CM oo r*. vO 4 o rH ^4 oo m CM CO pH pH O rH U OS rl H d U os rH W a po (0 a 4- pX 0 *rl >h 4-1 U (S c5 0) H a pC 3 rH H g 0) CO G s rH cO 4J o cc rH (0 a rH <0 'O CO 4J H pO 4J Q* oSX a X 4J*H O- C C G (-1 o H H H U e U u4J o N CO c O H O H O G a o <0 o H 4- H rH H *iH CO CO H X >* o rH o H Mn G CO <H V4 4) H o .o H w a CO pO 60 rH 4-1 0 u<0 3 (3 2C f*4 hJ <i N I I I I I I84 K HWBUI0012950 TABLE 21. PASSENGER CAR AND LIGHJa TRUCK USAGE OP NONASBESTOS DISK BRAKE LJNiNGS43 (See Table/A/for Police/Taxi option usage) -vffD5--;............. - - ---- I Nonasbestos lining (with Nonasbestos Vehicle type asbestos back) lining only 1 American Motors I 1980, Spirit, Concord 4's 1980, Spirit, Concord, Eagle 6's 1979, AMX 9 Buick 1980, Buick Electra 1 1979-80, Riviera 1980, Regal, Century 1980, Skylark (Power brakes) I 1980, Skylark (Manual brakes) 1976-80, Skyhawk 1978-79, Regal, Century (Power brakes) I 1978-79, Regal, Century (Manual brakes) 1976-79, Skylark 1976-77, Century (Manual brakes) 1973-75, Apollo (Manual brakes) I Cadillac Outer only Outer only Outer only I &0 I&0 I & 0 or I & 0 I&0 Inner only I&0 I&0 Outer only Outer only Outer only Outer only -- 1979-80, Eldorado (Diesel) 1975-80, Seville (Diesel) 1968-80, Commercial I&0 I&0 I&0 Chevrolet 1980, Monte Carlo, Malibu 1980, Citation (Power brakes) 1980, Citation (Manual brakes) 1976-80, Monza 1980, Chevette 1976-80, Camaro 1978-79, Monte Carlo, Malibu (Power brakes) 1978-79, Monte Carlo, Malibu (Manual brakes) 1976-79, Nova 1976-77, Malibu (Manual brakes) 1976-77, Vega 1973-75, Nova (Manual brakes) I & 0 or I & 0 I&0 Inner only I&0 Outer only Outer only I &0 Outer only Outer only Outer only I&0 Outer only (continued) 85 I HWBUI0012951 TABLE 21 (continued). Vehicle type Nonasbestos lining (with asbestos back) Nonasbestos lining only Chevrolet Truck 1978-80, El Camino 1979-80, C-, K-, P-20 1979-80, C-, P-30 1979-80, K-30 1979-80, P-30 (JF-9) (Front & Rear) 1979-80, G-30 1976-78, C-, K-, P-20 1976-78, C-, G-, P-30 Dodge \ 1978-80, Omni Dodge Truck 1976-78, Mini Bus 1976, W-300 Ford 1979-80, Fairmont V8 1980, Thunderbird 1979-80, Mustang V8, Turbo 4 1979-80, Fiesta 1980, Mustang V6 Ford Truck 1976-80, F-100 (4 x 4) 1977-80, F-150 (4 x 4) 1976-80, Bronco 1976-78, F-250 (Lt) 1976-80, E-250, F-250 (HD), E-350, F-350 1980, E-350 School Bus GMC Truck 1978-80, Caballero 1979-80, C-, K-, P-2500 1979-80, C-, P-3500 1979-80, K-3500 1979-80, P-3500 (JF-9) (Front & Rear) (continued) 86 I&0 I&0 I&0 I&0 I&0 I&0 I&0 or I & 0 or I & 0 I&0 or I & 0 or I & 0 I&0 I&0 I&0 I&0 I&0 I&0 Outer only I&0 I&0 I&0 I&0 Inner only I&0 I&0 I&0 I&0 I&0 I&0 or I & 0 or I & 0 fe I M fe I a HWBUI0012952 a TABLE 21 (continued). a Vehicle type a 1979-80, G-3500 1976-78, C-,K-,P-2500 1976-78, C-.G-,P-3500 a Mercury a 1979-80, 1980, 1979-80, Zephyr V8 Cougar Capri V8, Turbo 4 1980, Capri V6 a Oldsmobile Nonasbestos lining (with asbestos back) Nonasbestos lining only I&0 1&0 I &0 or I & 0 or I & 0 I&0 I&0 I&0 I&0 a 1980, 1979-80, 1980, Oldsmobile 98 Toronado Cutlass a 1980, 1980, 1976-80, Omega (Power brakes) Omega (Manual brakes) Starfire 1978-79, Cutlass (Power brakes) i 1978-79, Cutlass (Manual brakes) 1976-79, Omega 1976-78, Toronado i 1976-77, 1969-75, 1974-75, Cutlass (Manual brakes) Oldsmobile Commercial Toronado i 1973-75, Omega (Manual brakes) Plymouth I&0 I&0 I & 0 or I & 0 I&0 Inner only I&0 I &0 Outer only Outer only Outer only Outer only I&0 I&0 Outer only i 1978-80, Horizon Pontiac x I&0 i 1980, 1980, LeMans, Grand Prix Phoenix (Power brakes) I&0 or I & 0 I&0 i 1980, 1976-80, 1976-80, Phoenix (Manual brakes) Sunbird Firebird (drum rears) I&0 Inner only Outer only 1979-80, Firebird (organic disc rears) I&0 i 1978-79, LeMans, Grand Prix (Power brakes) 1978-79, LeMans, Grand Prix (Manual brakes) I&0 Outer only i (continued) i 87 i HWBUI0012953 TABLE 21 (continued). Vehicle type 1978-79, 1976-77, 1976-77, 1976-77, 1973-75, Phoenix Ventura LeMans (Manual brakes) Astre Ventura (Manual brakes) Toyota 1980, Corolla Coupe Nonasbestos lining (with asbestos back) Nonasbestos lining only Outer only I &0 Outer only Outer only Outer only I&0 Key: I = Inner Lining 0 = Outer Lining \ 1 I 0 I] t K I a a a a a H a o a HWBUI0012954 TABLE 22. POLICE AND TAXI USAGE OF NONASBE>TOS DISK BRAKE LINING ON FRONTS343 Vehicle type Nonasbestos lining (with asbestos backing) American Motors 1978, Concord Police, Taxi 1975-78, Matador Police Outer only Both I 8. 0 Buick 1971-80 1979-80 Buick Police, Taxi Century Police Both I & 0 Both I & 0 Chevrolet 1971-80, 1977-79, 1979-80, Chevrolet Police, Taxi Nova Police Malibu Police Both I & 0 Both I & 0 Both I & 0 Chrysler 1976-80, 1978-80, 1977-80, Chrysler Police, Taxi Cordoba Police LeBaron Police, Taxi Both I & 0 Both I & 0 Both I & 0 Dodge 1977-80, 1979-80, 1977-80 1977-78, 1977, Aspen Police, Taxi St. Regis Police, Taxi Diplomat Police, Taxi Monaco Police, Taxi Royal Monaco Police, Taxi Both I & 0 Both I & 0 Both I & 0 Both I & 0 Both I & 0 Ford 1978-80, 1976-80 1976-80, 1978-79, Fairmont Police, Taxi Ford Police, Taxi Granada Police, Taxi LTD II Police, Taxi Both I & 0 Both I & 0 Both I & 0 Both I & 0 Mercury 1978-80, 1976-80, 1976-80, Zephyr Police, Taxi Mercury Police, Taxi Monarch Police, Taxi Both I & 0 Both I & 0 Both I & 0 (continued) 89 HWBUI0012955 m iss** I TABLE 22 (continued). ; ' Vehicle type Nonasbestos lining (with asbestos backing) Oldsmobile 1971-80, Oldsmobile, Police 1979-80, Cutlass Police -A . . . j. Both I & 0 Both I & 0 Plymouth 1977-80, 1977-80, 1978, Pontiac Volare Police, Taxi Gran Fury Police, Taxi Fury Police, Taxi \ Both I & 0 Both I & 0 Both I & 0 I I I I I 1 1971-80, Pontiac Police, Taxi 1979-80, Phoenix Police Both I & 0 Both I & 0 I Police and Taxi usage of nonasbestos disk brake linings was as a Police/Taxi option -- actual usage depended on customers ordering that option. Ford-Mercury in 1976-78 also had non asbestos disk rears for the Police/Taxi option. I Key: I = Inner Lining 0 - Outer Lining 90 HWBUI0012956 &** CU^n Ar csypsw2Zd pf&U a^ji dU-- h utfXL \^Q*j o^ji ^Gsi/^Jl yn^fvv^. V ,1 ft % e T- ^'T'-^Tr^ HWBUI0012957 I . fu^~****u' Semimetallic or resin bonded metallic brakes are presently used in heavy- duty automotive applications such as police cars and taxis. Semimetallic disk pads dry-iil rpnd were able to attain overall excellent properties at both low and high temperatures which ordinary Class A or Class B organics could not accomplish. Downsizing of vehicles., resulting in smaller- fiorrt brakes-and higher operating temperatures (lias helped semimetallics gain a foothold heret Semimetallic drum l-inJftfjg^firstTnsed^in air brakes in Heavy-duty trucks used in the logging industry (an extremely severe application), have been attempted to be scaled down to small drum brakes, but the basic nature of-semimetallics has not lent itself to the accurate segment configuration required in this application. Here, semimetallics do not possess the necessary green strength, are difficult to bend into the proper shape, and are more brittle in cured form and therefore subject to cracking. Modifications to date have generally resulted in a product that cannot achieve commercially-acceptable performance character! ics. Work in this area therefore continues. The first generation of asbes ree drum linings is currently under evaluation by vehicle manu- facture ile their performance may be superior to asbestos-Agatee-linings, inings tend"perForm^erTStit^ _ ynise than ashpstns linings. Vthev aremcyfe"" than asbes^S^ra^Mf; "FKaFisT^thes-faaye higher cause more^aar^^^G^JentlyT^Sffl^nretaWlSsare 50 toTMSTpercent more expensive laSSJgsrmt with increased production it is estimated that costs would drop to within 25 percent of asbestos br 20 percent of passenger cars usij disk brakes as original equipme: most original equipment disk braRi . brakesS^iacee equipped w__l_c_n semimferalli d it is e^rmated that in 5'n passenger cars and light trucks will be^semimetallics. ---- -----------~ ___ ' jAs^Table 21 shows. General Motors, in the past, has "a. hybrid brake cpifSisting of one semimetallic and one organic* asbestos^ in some mass- produced passenger.cars, Here the asbestos ulates the brake fluids from heat .genei*tcr h; Semimetallic surface during braking, but never actually touches the?fcto Surface. In effect, the asbestos content of the brakes is reduced. mpdxed to asbestos-lined disk brakes, the hybrid brakes have a higher coefficient of friction, higher heat resistance, and wear longer but aro^Tfibra nol-ay and moEfiL-oxpnnsive. While some industry sjiurcas^feelr^fnat erTorperformance, others believe that trends to lower speed limits and lighter weight cars will reduce the need for high performance brakes.1 This uncertainty is reflected in Table 21 where, for example, American Motors reports using a nonasbestos brake lining with an asbestos back on outer brake positions only on their 1980 Spirits while Chrysler uses nonasbestos linings with an asbestos back on both inner and outer brake positions on their 1980 Dodge Omnis. weights and high landing speeds of modern aircraft and highrequire friction materials with high thermal stability. Cermet 'possess this property and, for this re^sepr^heir share-of the air- rket continues to grow. Current!^, 95 percent of all new corat use cermet brakes. The remaining 5 percent are carbon wmm HWBUI0012958 P 1) ^ ti b'&f ^ t{~ rs \/)u(?/*L -.1 I Is I J ? 'A^ fc{! I "i* -1 HWBUI0012959 0h Cermet materials have also been used for railcav brakes, but, in the last several years, nearlv^all rairtcyir'-hrqkes have been made of rubber poly meric binders with variou^frictionizersamd friction modifiers.I*6 In general, asbestos and lead are not present- in thgse brakes.47 Substitute Product Manufacturing Summary-- Manufacturing process--Semlmetallic disk pads are made using a dry-mix process. Ingredients are blended, then formed into briquets at room temperature and 27.6 to 41.4 MPa (4000 to 6000 psi). The briquets are then hot-pressed at 160 to 180C (320 to 360F) for 5 to 15 minutes at 27.6 to 55.2 MPa (4000 to 8000 psi). The pads are then cured at 220 to 300C (430Vttr570F) ~fgf~4~to--~ V|r>,nrQ, grinding produces the finished disk pads^/ Semlmetallic blocks^ -lire produced from the same dry-mix as semlmetallic disk pads, briquets are~ ^formed at~1073~to 17.2 MPa (1500 to 2500 psi). Briquets may be heated to 90C (195F) for 15 to 30 minutes to reduce blistering during hot pressing. Blocks are formed by heating at 130C to 150C (265 to 300F) at 13.8 to 20.7 MPa (2000 to 3000 psi) for IQ to 30 minutes. After cutting to size, blocks are ground to the appropriate size, followed by curing [unconfined for 15 hours at 180C (355F) or confined for 6 hours at 280C (535F)]. The final block requires grinding, drilling and chamferring. Cermet materials are manufactured using the powder metallurgy technique. Desired amounts of individual ingredients are weighed, mixed, compacted, sin tered, and coined (or recompacted). The sintering is performed in a reducing or neutral atmosphere, and the sintering temperature has to be high enough so that the metal ingredients will adhere to each other. In carbon composites, carbon or graphite fibers are embedded in a carbon or graphite matrix. The matrix can be formed by two methods: chemical vapor deposition and coking. In the case of chemical vapor deposition, a hydro carbon gas is introduced into a reaction chamber in which carbon formed from the decomposition of the gas condenses on the surface of carbon fibers. An alternative method is to mold a carbon fiber-resin mixture into shape and coke the resin precursor at high temperatures. In both of the methods the process has to be repeated until a desired density is obtained. I 8 a a fa a a a E Name and number of~jnanufac.feu>Eei;-sg-Table 23 lists nonasbestos brake manufacturers, thei^^lgcgt^o^s^/a^d^thjySubstitute materials they use. Semimetallic disk brpkejfcwere origiiml^ro^ji^ied and produced by Bendix Corporation. Bendix has reported that new jsquiff)ment was required for their manufacture. Abex CorporatioS~and~Ra5'bestos-Manhattan, Inc. also make semlmetallic disk bral Cermet materials are manufactured _hv~Rpndix Corporation and ^bex^Gorpora tion. Abex also makes fiberglass |sk brak<p& Carbon composite" brakes/are manufactured by Dunlop., American Fitier-gna Abrasives has been marketing an asbestos substitute called Kay-O-Cel, made primarily of cellulose and clay wastes, which is being7tested in brake linings.*2 Kevlar aramid fiber prod ucts are made by E.jp. DuPont de Nemours and Co., Inc. of Wilmington, DE. Raybestos-Manhattan Makes Rayflex for brakes in off-the-road vehicles. /6 HWBUI0012960 |jfv /Ll/^y^sk.. ) H&s/& Tt ^ /M-VJW ^ ^y- V o^oy^ HWBUI0012961 TABLE 23. NONASBESTOS BRAKE MANUFACTURERS Manufacturer Bendix Corp. Abex Corp. Location Substitute material \ .................. Southfield^.. MI* , Troy, NY Cleveland, TN Semimetallics Cermets Cleveland, OH Troy, MI Winchester, VA Semimetallics Cermets Fiberglass Raybestos-Manhattan, Inc. Stratford, CT Trumbull, CT Semimetallics Dunlop f Carbon composite American Filler & Abrasives ''"-Htigor, MI Kay-O-Cel (cellulose and clay) Delco-Moraine Div., General Motors Corporation Dayton, OH Semimetallics E.I. DuPont deNemours and Company Wilmington, DE Kevlar (aramid) ^Designed at this location A.Location unknown Production volumes--Although production figures foj individual firms are not avvaaiilablee, it is knpwh that semimetallic material^a* used r 40 percent of all front disk brakes Cermet materials are used almost exclusively for--. aircraft brakes and control 95 percent of the current market Carbon composite^ brakes are used for the remaining 5 percent of the aircraft brake market. Kevlar products are available from a commercial production facility whi being expanded to 20 million kg/yr capacity.40 \ COST COMPARISON The basic cost of the substitute friction products involves many complex factors, including the amount and types of materials used and the basic raw materials cost. The fixed and variable costs of manufacturing can differ greatly, based on the type of process and its complexity as well as production volumes, labor costs, energy costs, and process yield. Administrative costs and handling/distribution costs are also significant variables as are imple mentation costs. Here, it"appears that timing of test programs will be impor tant as expenses could be minimized by converting to asbestos-free materials as part of the scheduled new vehicle^esigrr ~pTUgiams, where 3ige system testing ic.airpgHy pocessarvA Life cycle costs are also a necessary Ieration; semimetallics have~KTgher life cycle costs than organics, yet they are smaller and lighter and therefore result in better fuel economy.50 93 '\ HWBUI0012962 Although exact costs for semimetallic friction materials are not available, their improved performance compensates for their higher costs due to more expen sive ingredients, higher specific gravity, and more costly processing require ments. Currently, they are good candidates'^replacet organic friction mater ials in disk brakes. Preliminary cost estimates indicate that asbestos-free brake lining may cost 20 to 25 percent more than current linings with disk brakes at 20 to 100 percent greater cost. These preliminary estimates are highly dependent on the characteristics of semimetalllcs making them extremely difficult and costly to process as drum lining segments. Consequently a new class of\friction materials is currently under development to suit this applica tion. ; Cermets cost three to five times as much as asbestos friction materials, Costs for iinposites are not available but they are considerably more expensive ts. Kevlar (aramid) fiber is available in a short pulp form at .25/kg). Only small amounts of this fiber are reported to be requi fep filler materials, making the cost between 20 and 40 percent greater--tl an for asbestos, with lifetime costs approaching those of asbestos.51 Table 4 lists the costs of various fibers proposed as substi- tutes for asbestos friction material. TABLE COSTS OF MATERIALS PROPOSED AS SUBSTITUTES FORvASBESTOS IN FRICTION MATERIALS1 \ Xifif Material jAsbestos Price - $/lb ($/kg) 0.05 - 0.15 (0.11 - 0.33) I Fibrous glass 0.05j-0.75 (0.11 - 1.65) o.sb-Azr Mineral wool 0.15 (0.33) Potassium titanate fibers 1.00 - 1.25 (2.20 - 2.75) Graphite and carbon fibers 10.00 - 12.00 (22.00 - 26.50) Wollastonite Aramid fibers =0?kW0.33) ^ 6.00 - 8.0oX3.25 - 17.65) CURRENT TRENDS The need for more energy-efficient automobiles and trucks has put an in i -j; creased demand on friction materials. Major trends are towards smaller, lighter, more efficient vehicles with manual transmissions and smaller brakes. Although organic friction materials will continue to serve the drum brake in dustry, more and more vehicles are being equipped with ventilated disk brakes. Ventilated brakes may be replaced by solid disk brakes to save weight. As brakes become smaller, braking temperatures become higher. Class B organic and semimetallic friction materials will replace Class A organics because they have higher thermal stability. Heavy vehicles are using more and more effi cient disk brakes. More cermet friction materials will be used in heavy-duty clutches. The trend in aircraft brakes may be toward lighter carbon composite materials. 94 HWBUI0012963 '^f~jjz kxifaH- r i ^yVr$^- 7, J& HWBUI0012964 Kr^ * Because of present and future health standards, some automob facturers are in favor of (oval of asbestos and lead from brakes. automakers have cut the av asbestos content of disk brake 0.45 kg to about 28 grams Both General Motors and Ford have asked suppliers to seek ways to totally eliminate asbestos from disk brakes. Be cause of the curved shape required for drum brakes, no suitable substitute for asbestos is readily available. However, Rockwell International Corpora tion, manufacturer of about 60 percent of the brakes used in heavy trucks, has a major development effort aimed at producing nonasbestos brakes underway.52 Semimetallics are the best available substitute and aew^constitute$approx- imately 40 percent of original equipment front disk brakes. One problem with -1new heavy-duty friction materials is high noise levels. To prevent noise pollu tion, noise-free organic friction materials will continue to be used for trucks and buses. Borg-W^rner Corporation5^^nd Abex Corporation35 (among others) have developed proprietary substitutes for automobile brake friction materials. Some are in the consumer testing stage, but no additional information is available at this time. A company such as Bendix is not aggressively pursuing licensing policies but does have many license agreements for the international market which usually J.nclude territorial exclusions. Significant company funds>4 JSauJfyi have been expendeaktc?aeve^rop this new technology. Borg-Wamer has spent several million dollars to develop asbestos-free friction materials for em ployee safety and may enter license agreements or manufacture in Brazil.50 Although Raybestos-Manhattan, Inc. stated publicly in May 1979 that the company would "halt" the manufacture of brake linings and other that contain asbestos by using a blend of 10 to 15 components (40 pe iber, 20 percent resin binder, and 40 percent friction modifiers), disc ith company representatives revealed that this was not strictly tr e company has developed some nonasbestos substitute products for certa implications and has committed itself to a search for nonasbestos substitutes, but the complete removal of asbestos from their friction materials is not expected in the foreseeable future. Small brake manufacturers have a real problem with capital equipment and financing of nonasbestos friction products.50 Part of the problem in designing new brake systems is simply that it takes time. Both the materials used and their properties are a result of optimiza tion procedures, with extensive testing programs both by the material supplier and by the customer to ensure suitability, quality, and regulatory conformance. For evolutionary changes, an example of which would be an improved organic disk pad utilizing the same basic components (asbestos, resin, and modifers) but with better wear, improved fade resistance and the same friction and noise properties, years are required. In this case, asbestos organic linings are essentially the product of 40 years of evolutionary changes. Supplier develop ment and validation testing requires 18 to 24 months, consumer application testing 12 to 18 months, and 6 months manufacturing lead-time, or, a total of 3 to 4 years for one evolutionary change. In addition, there are revolution ary changes, which actually advance the state-of-the-art, that are more dif ficult to come by, and are even longer in the developmental phases. It is 95 J HWBUI0012965 unrealistic to apply a timetable to inventions, but for establishing the fea sibility of a new concept, 12 to 18 months is a reasonable time period to be expected. Reducing that concept to a product with some or most of the basic characteristics can take another 12 to 24 months. Formulation development for commercial application and validation of properties adds 24 to 36 months. An additional 12 to 18 months is required for customer application testing plus 6 months manufacturing lead-time, or a total change-over requiring 5% to 8h years. Eliminating asbestos from automotive friction materials is consid ered a revolutionary change. As ideas on substitute products came into being around 1975 and later, the first evolutionary changes are now underway to help develop asecond generation of materials which have improved properties and the mult-ipl^ types and assortment of formulations necessary for different application^.^6 J As indicated, semimetallic disk brake 2ri$!as' without asbestos in either the friction material or the backing layer are currently in use, but cannot be used in all vehicle applications. An orderly transition is expected to occur, approaching 100 percent utilization by 1985. Development of asbestosfree organic disk-brake lingi/ and semimetallic drum brake linings is contin uing at Bendix with production implementation not yet able to be predicted. In addition, Bendij^ifr lrrcKe^^lnal development stage of work on first genera tion asbestos-free organic drum-brake linings and some asbestos-free blocks are available commercially for heavy-duty applications, with the first signi ficant production release expected in 1982. All of these new developments show continued effort from industry to move towards a dominance of asbestos- free products in the friction materials area. /) kloclc*- CONCLUSION .Lev^T- Semimetallic disk brakes, originally^dgslgned and^pfOdu^d by Bendix Corpora'Cion and now also manufactured by" ,-Tris t,- Bpeg<-fc^d-**^ are expected to increase market share relative to asbestofe-disk-brakSST^in fact, it is pro jected 4** /that in 5 yaacgk nearly all original equipment disk brakes made for passenger cars and light trucks will be maee--wwiitth seemmiimmeetatallilclisctS.r.d^i>i..i<)C.,..>>>1ri JL. At the present time a nonasbestos product for drum brake linings for pass enger cars is not available commercially. However, intense research in this area is underway, with specifics still proprietary at this time. The first commercially-available nonasbestos drum lining may contain some combination of steel fibers, synthetics, cotton, ceramic, carbon, natural materials, glass, and mineral fiberd/lFor the model year 1980, commercial nonasbestos linings were not availablefor drum brakes; however, Bendix Corporation is appar ently very close t&"marketing this kind of products. Performance character^ tics of the nonasbestos lining versus the asbestos lining are not availab>] lf.36J As for cermet brake linings, once the problem of their interaction with hydraulic brake fluid can be solved, their use may grow. With all of the current research into brake lining substitutes, a nonpsbestos product for more universal use should become available in the future. 96 a a a a a n I: n B i: is n n n IS IS n n HWBUI0012966 Clearly, the design of the entire braking system has a great influence on the types of friction material that can be used. The lack of readily avail able nonasbestos drum brakes^o^trasted with the^pr-ogress^^nrd- total-ly^as^- bestos -freedisk braked underscores thjLs-'polnt. Redesign of motor shafts or -the stator on which -the friction material is mounted could conceivably contriJ^-bute to the elimination of asbestos from brake linings./ However, redesign appears to be given less consideration than the search for a material to re place asbestos for the following reasons: Brake systems in use have been time tested and proven effective. Changes in the existing systems would require that the system and the asbestos replacement both be tested intensively. Problems could result if replacements are not made of materials similar to those of the original equipment, as the entire brake system is designed as a unit. Without careful study, substitution may cause safety or wear problems. Time is often needed to heal these faults. Testing requirements are signifi cantly reduced if only the asbestos substitute is to be evaluated. Any new brake system must be suitable to be maintained by automobile dealers and service stations. Any complex new system or radical changes in brake system construc tion that would be difficult to maintain properly would be unacceptable. Equipment designed to produce brake systems currently in use would either have to be replaced or modified to produce a - new brake system, possibly necessitating large capital expen ditures at a time the automotive industry is feeling finan cial constraints. The many manufacturers of brake linings must respond to the needs of their customers. Until the automobile manufacturers supply different product specifications, as for the friction material component of a new braking system, the brake lining manufacturers will continue to supply a traditional product. Brake system changes must be initiated by original equipment manufacturers. It is much easier, more readily acceptable and much less risky for brake lining manufacturers to attempt to find a substitute for asbestos rather than effect a complete redesign of braking systems. Consequently, most research is focussed on the search for substitutes. The outlook for the use of asbestos in friction material is, at best, mixed. The majority of the industry's products--ace_used in passenger auto mobiles and, as such, are influenced by th^vagaries_J>f the buying public: if a lot of new cars are being sold, a lot o?~new "brakes will be required. Conversely, if fewer new cars are sold, more used cars in the marketplace 97 HWBUI0012967 will result in more sales of replacement brake^. Further uncertainty is in troduced by the American automobile manufacturers' avowed intentions to eliminate asbesto^-from orxgina.T~e&jiipment brakes by the 1985* model year. If a successful/^ubstitute is foyna, asbestos consumption in friction ma terials will drop preclpjiLgnslyT Yet it is unclear whether the target date represents the culmination of a carefully thought-out phased production in troduction or is merely the consequence of wishful thinking. Whichever situa tion holds will provide/the key to any projections of the use of asbestos in friction materials. *Raybestos Manhattan plans to eliminate asbestos from its friction material products by 1982.55 98 HWBUI0012968 REFERENCES 1. Wright, M. D., et al. Asbestos Dust Feasibility Assessment and Economic Impact Analysis of the Proposed Federal Occupational Standard, Part I: Technological Feasibility Assessment and Economic Impact Analysis. U.S. Department of Labor, Occupational Safety and Health Administration. Washington, D.C. Contract No. J-9-F-6-0225 Task 2. September 1978. p. v-2. .2 Michaels, L. and S. S. Chissick. Asbestos - Volume 1: Properties Applications and Hazards. New York. John Wiley and Sons. 1979. p. 553. 3. Gregg, R. T. Development Document for Effluent Limitations Guidelines and New Source Performance Standards for the Textile, Friction Materials, and Sealing Devices Segment of the Asbestos Manufacturing Point Source Category. U.S. Nat. Tech. Inform. Service PB-240/860. 1974. 4. Twiss, S. B., and E. J. Sydor. U.S. Patent 3,007,890. November 7, 1961. Rewarded to Chrysler Corporation. __ \ 5. } Jacko, M. G., and R. T. Du Charme. Brake Emissions: Emission Measure ments from Brake and Clutch Linings From Selected Mobile Sources. U.S. Nat. Tech. Information Service, PB-222-372. .6 Clifton, R. A. Mineral Industry Surveys - Asbestos in 1978. U.S. Depart ment of the Interior, Bureau of Mines. Washington, D.C. August 22, 1979. p. 3. 7. Telecon. Eugene Conner, Johns-Manville, with David Cook, GCA. January 17, 1980. Asbestos prices. .8 Jacko, M. G. and S. K. Brake Linings and Clutch Facings. Encyclo v. pedia of Chemcial Technology, Third Edition, Volume 4. New York. John Wiley and Sons. 1979, pp. 202-212. 9. Bark, L. S., D. Moran, and S. J. Percival. Chemical Changes in AsbestosBased Friction Materials During Performance - A Review. Wear. 34:131-139. 1975. .10 Meylan, W. M., et al. Chemical Market Input/Output Analysis of Selected Chemical Substances to Assess Sources of Environmental Contamination: Task III - Asbestos. EPA-560/6-78-005. August 1978. pp. 63-65. 99 HWBUI0012969 11. Telecon. Raybestos-Manhattan, Inc. with David Cook, GCA. . February 28, 1980. Friction products manufactured. v12. Telecon. Kevin Peppard, Bendix Corporation, with David Cook, GCA. February 28, 1980. Friction product manufacturers. 13. Telecon. H. K. Sleeth, Porter Company, with Robert Bouchard, GCA. February 29, 1980. Friction products manufactured. 14. Telecon. Terry Blaine, Borg-Warner Corporation, Spring Division with Robert Bouchard, GCA. March 4, 1980. Friction products manufactured. 15. Telecon. Roy Huckabee, Nuturn Company, with Robert Bouchard, GCA. February 29, 1980. Friction products manufactured. 16. Telecon. Earl Fygert, National Friction Products Corporation, with Robert Bouchard, GCA. February 29, 1980. Friction products manufactured. 17. Telecon. Bill Shine, Auto Specialists Manufacturing Company, with Robert Bouchard, GCA. February 29, 1980. Friction products manufactured. 18. Telecon. Standco Industrial with Robert Bouchard, GCA. February 28, 1980. Friction products manufactured. 19. Telecon. Jack Payton, Friction Products Company, with Robert Bouchard, GCA. February 29, 1980. Friction products manufactured. 2D. Telecon. Andrews, Royal Industrial Brake Products, Inc. with Robert Bouchard, GCA. February 28, 1980. Friction products manufactured. 21. Telecon. Montgomery, Reddaway Manufacturing Company with Robert Bouchard, GCA. February 29, 1980. Friction products manufactured. 22. Telecon. Molded Industrial Friction Corporation with Robert Bouchard, GCA. March 3, 1980. Friction products manufactured. 23. Telecon. Wheeling Brake Block Manufacturing Company with Robert Bouchard, GCA. February 29, 1980. Friction products manufactured. 24. Telecon. Reginal D. Kelley, Force Control Industries, with Robert Bouchard, GCA. March 3, 1980. Friction products manufactured. 25. Telecon. Brassbestos Manufacturing Corp. with Robert Bouchard, GCA. March 3, 1980. Friction products manufactured. 26. Telecon. Paul Biondo, Auto Friction Corp., with Robert Bouchard, GCA. March 3, 1980. Friction products manufactured. 27. Telecon. Robert Randolf, Gatke Corporation, with Robert Bouchard, GCA. March 3, 1980. Friction products manufactured. 100 HWBUI0012970 28. Telecon. Lasco Brake Products Company with Robert Bouchard, GCA. March 3, 1980. Friction products manufactured. 29. Telecon. Appollageno, MGM Brakes, Inc., with Robert Bouchard, GCA. March 3, 1980. Friction products manufactured. 30. Telecon. Carlisle Corporation with Robert Bouchard, GCA. March 3, 1980. Friction products manufactured. 31. Telecon. Thiokal Chemical Corporation with Robert Bouchard, GCA. March 3, 1980. Friction products manufactured. 32. Telecon. Joseph Minky, P.T. Brake Lining Company, Inc., with Robert Bouchard, GCA. March 4, 1980, Friction products manufactured. 33. Telecon. Mr. Baltz, Baltz Company, Inc. (distributors for Eaton Cor poration), with Robert Bouchard, GCA. March 4, 1980. Friction products manufactured. 34. Clifton, R. A. Asbestos. United States Bureau of Mines. Washington, D.C. Mineral Commodity Profile. July 1979. p. 9. 35. Telecon. George Bason, Abex Corp., with David Cook, GCA. February 11, 1980. Asbestos substitutes in friction materials. V36. Jacko, M. G., C. M. Brunhofer and F. W. Aldrich. Nonasbestos friction materials. Speech presented at the EPA/CPSC substitutes to asbestos conference, July 14-16, 1980, Arlington, VA. _ 37. Pye, A. M. A Review of Asbestos Substitute Materials in Industrial Applications. Journal of Hazardous Materials. (Netherlands). 137-138. 1979. 38. Hayes, J. S., American Kyanol Incorporated, letter to George A. Peters, Registered Professional Engineer, November 20, 1979. 39. U.K. Patent Application GB2018806A, filed 22 August 1978. 40. Loken, Halvar Y. (E.I. duPont deNemours & Co., Inc.), Asbestos Free Brakes and Dry Clutches Reinforced with Kevlar Aramid Fiber, SAE Technical Paper Series, paper presented at Earthmoving Industry Conference, Peoria, IL, April 14-16, 1980. 41. Green, A. K., and A. M. Pye. Asbestos Characteristics, Applications, and Alternatives. Fulmer Research Institute, Fulmer Special Report No. 5, ISSN 0427-7457. 1976. 42. Allen, A. W., and R. H. Herron. U.S. Patent 2,948,955. August 16, 1960. 43. Drislane, E. W., Executive Director, Friction Materials Standards Institute, letter to Richard Guimond, EPA OPTS, undated, received at EPA April 21, 1980. 101 HWBUI0012971 & 44 . Telecon. M. JackoJ Bendix Research Labs, with August 1979,__Sjsmimetallic Disc Brakes. (A*#' ::;H 45. Telecon. -Ittka Jacko) Bendix Research Labs, wit November 19,._19-79. Cermet brake linings. i, ]'i, -cy K : ;A. 46. Telecon. Jack Reynolds, Johns-Manville, with D." February 19, 1980. Railcar brakes. 47. Telecon. Leon Kopyt, Mass Transit Systems Corp GCA. February 19, 1980. Railcar brakes. ii Cook, 48. __________ , "Annual Reports - 1979 Raybestos-Manh N. 11, p. 14, May 1980. ` s tos, V. 61, 49. Telecon. Wayne Quasar, Westinghouse Air Brake t GCA. November 19, 1979. Cermet brakes. \ 50. Drislane, M. Friction Materials Standards Insti (GM) and Mr. Brunhofer (Bendix). Roundtable Dis Products, USEPA/CPSC. "Alternatives to Asbestos Arlington, VA. July 14-16, 1980. I- Nancy Krusell, f f}-: C- ;>. Ward - .ion 51. Moulton, E.I. duPont deNemours & Co., discussior Roundtable Session, EPA/CPSC "Substitute to Asbe Arlington, VA, July 14-16, 1980. u-J " . Products :e, 52. Business Week. "The Growing Need for Asbestos f :- f Week, December 3, 1979, p. 98D. Business 53. Telecon. Robert Curran, Borg-Warner Corp., witt February ,1-1 r*l980-^Asbestos substitutes in fric ( 54. Telecon. JackoJ Bendix Research Labs, with March 3, 1980^ Br^ake compositions. A. . 55. Castleman, Barry and S.L. Berger. Asbestos Subs July 8, 1980. -y- 56. Telecon. Bill Ferk, Scan-Pac Manufacturing Com] (414) 241-3890, with Nancy Krusell, GCA Corporal Division. April 22, 1981. They also have a pi? but do not use asbestos there. logy , KY 57. Telecon. Tom Nick. Delco-Moraine Division of ( Dayton, OH. (513) 227-5000, with Anne Duffy, G( nology Division. April 14, 1981, Call No. 7. . Corporation, >n, GCA/Tech 102 mmm HWBUI0012972