1、 ENGINEERING MATERIAL SPECIFICATION Date Action Revisions Rev 02 2012 05 07 N Status No usage or replacement N. Benipal, NA 2006 09 25 Revised Inserted 3.0; Deleted 3.1, 3.6 & 4 1986 08 22 Released CF4QRD888002-430 Controlled document at www.MATS Copyright 2012, Ford Global Technologies, LLC Page 1
2、of 3 CARBON BRUSH MATERIAL (2153-2660 micro ohm.cm ESF-M99G147-A SPECIFIC RESISTANCE) NOT TO BE USED FOR NEW DESIGN 1. SCOPE The material defined by this specification is a hard carbon brush. 2. APPLICATION This specification was released originally for material used as a carbon brush in fuel pump m
3、otors. 3. REQUIREMENTS Material specification requirements are to be used for initial qualification of materials. 3.0 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Material suppliers and part producers must conform to the Companys Standard Requirements For Production Materials (WSS-M99P1111-A). 3.2
4、 SPECIFIC RESISTANCE 2153 - 2660 micro ohm.cm Test Method: The apparatus consists of 2 jaws which can be closed firmly against the ends of the test specimen. The jaws should be faced with silver-plated copper gauze, backed with resilient pads to insure uniform current distribution into the ends of t
5、he piece. The size of the test specimen is immaterial, providing it fulfills the following requirement for accurate results. The length should be at least 4 times the width and thickness dimensions and the spacing between pointers should be no more than 1/2 the length of the specimen. For a test spe
6、cimen the specific resistance is defined as follows: r = E x A x 1000 I x L where: r = specific resistance in micro ohn.cm E = millivolt drop between pointers A = cross-sectional area, cm2 I = current in amperes L = pointer spacing, cm The convenient method for obtaining readings of specific resista
7、nce that are a multiplier of the potential drop in millivolts is to proceed as follows: Use voltmeter (or millivoltmeter) pointers that are accurately spaced 2 cm apart. Set the current at 1.97 times the value of the cross-sectional area of the specimen in square centimeters: ENGINEERING MATERIAL SP
8、ECIFICATION ESF-M99G147-A Copyright 2012, Ford Global Technologies, LLC Page 2 of 3 r micro ohm.cm = E x A x 1000 = E x A x 1000 = 254E I x L 1.97A x 2 If the specimen is not long enough to use a 2 cm spacing between pointers, another method is to make the pointer spacing equal to the width of the s
9、pecimen, and the current setting 3.94 times the thickness, then: r micro ohm.cm = E x A x 1000 = E x W x T x 1000 = 254E I x L 3.94T x W 3.3 SCLEROSCOPE HARDNESS Test Method: Use a Shore Scleroscope instrument with a diamond-pointed steel hammer standardized for carbon. Mount and level the instrumen
10、t on a firm support. The anvil of the instrument must be kept clean at all times. The material is placed on the anvil, and the tube is lowered firmly against the test piece. At least 6 readings (in different areas) should be taken on each specimen to obtain average hardness. 3.4 APPARENT DENSITY 2.0
11、 - 2.2 g/cm3 Test Method: The apparent density is the density of the mass, including the voids or pores, and is expressed in the following manner: Apparent Density = Weight in Air Weight in Air - Weight in Water The specimen to be tested must first be coated with a thin coating of grease to prevent
12、water absorption. The piece is then weighed in air and the value recorded. It is then weighed while completely submerged in water, with special care being taken to eliminate all air bubbles from the specimen. Alternate Method: Finish the specimen to such a shape that the volume can be accurately mea
13、sured. Then, if the specimen is weighed (g) and such weight divided by the volume cm3, the result is numerically equal to the apparent density by the formula: Apparent Density = Weight, g Volume, cm2 3.5 TRANSVERSE STRENGTH, min 6.0 MPa The transverse strength refers to the strength of the material
14、when tested as a simple beam under load. Test Method: The specimen is supported at each end by a 1.6 mm radius knife-edge. A load is gradually applied at a point exactly midway between the supports through a third 1.6 mm radius knife-edge until rupture occurs. Calculate the transverse strength as fo
15、llows: S = 3 x L2 x P 2 x h x b ENGINEERING MATERIAL SPECIFICATION ESF-M99G147-A Copyright 2012, Ford Global Technologies, LLC Page 3 of 3 where: S = maximum stress, MPa L = length between supports, mm h = thickness of specimen, mm b = width of specimen, mm P = load at instant rupture occurs, N By using a length between supports of 20 mm and a test specimen 5 mm thick by 6 mm wide and long enough to overlap supports, the formula reduces to: S = 3 x 20 x P = 0.2P 2 x 5 x 5 x 6
