1、 ENGINEERING MATERIAL SPECIFICATION Material Name Specification Number Date Action Revisions 2000 09 25 Revised Updated and renumbered A. Cockman 1987 - 12 - 01 CF4R RD 107 002 - 87 878788787 Released Printed copies are uncontrolled Page 1 of 4 Copyright 2000, Ford Global Technologies, Inc. CARBON B
2、RUSH MATERIAL ESF-M99G152-A (2000-2500 micro ohm x cm SPECIFIC RESISTANCE) 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 carb on brush in fuel pump motors. 3. REQUIREMENTS Material specific
3、ation requirements are to be used for initial qualification of materials. 3.1 QUALITY SYSTEM REQUIREMENTS Material suppliers and part producers must conform to the Companys Quality System Requirements. 3.2 SPECIFIC RESISTANCE 2000 - 2500 micro ohm x cm Test Method: The apparatus consists of 2 jaws w
4、hich can be closed firmly against the ends of the test specimen. The jaws should be faced with silver - plated copper gauze, backed with res ilient pads to insure uniform current distribution into the ends of the piece. The size of the test specimen is immaterial, providing it fulfills the following
5、 requirement for accurate results. The length should be at least 4 times the width and thicknes s dimensions and the spacing between pointers should be no more than 1/2 the length of the specimen. For a test specimen the specific resistance is defined as follows: r = E x A I x L x 1000 Where: r = sp
6、ecific resistance in micro ohm x cm E - millivolt drop between pointers ENGINEERING MATERIAL SPECIFICATION ESF-M99G152-A Page 2 of 4 Copyright 2000, Ford Global Te chnologies, Inc. A = cross - sectional area, cm 2 I = current in amperes L = pointer spacing, cm The convenient method for obtaining rea
7、dings of specific resistance 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 centimete
8、rs: r (micro ohm x cm) = E x A x 1000 = E x A x 2 x 1000 = 254E I x L 1.97A 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 specimen, and the current setting 3.94 times the thickness , then: r (micro o
9、hm x cm) = E x A x 1000 = E x W x T x 1000 = 254E I x L 3.94 T x W 3.3 SCLEROSCOPE HARDNESS 25 - 45 Test Method: Use a Shore Scleroscope instrument with a diamond - pointed steel hammer standardized for carb on. Mount and level the instrument on a firm support. The anvil of the instrument must be ke
10、pt 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) shou ld be taken on each specimen to obtain average hardness. 3.4 APPARENT DENSITY 2.0 - 2.2 g/cm 3 Test Method: The apparent density is the den
11、sity 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 water absorption. The piece is then weighed in air and th
12、e value recorded. It is t hen 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 measured. Then, if the specimen is wei ghed (g) and such we
13、ight divided by the volume (cm 3 ), the result is numerically equal to the apparent density by the formula: Apparent Density = Weight, g Volume, cm 3 3.5 TRANSVERSE STRENGTH, min 3.0 MPa ENGINEERING MATERIAL SPECIFICATION ESF-M99G152-A Page 3 of 4 Copyright 2000, Ford Global Te chnologies, Inc. The
14、transverse strength refers t o the strength of the material 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 r adius knife -ed
15、ge until rupture occurs. Calculate the transverse strength as follows: S = 3 x L x P 2 x h2 x b 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 Use a length between supports of 20 mm and a te
16、st specimen 5 mm thick by 6 mm wide and long enough to overlap supports. The formula reduces to: S = 3 x 20 x P 2 x 5 x 5 x 6 = 0.2P 3.6 SUPPLIERS RESPONSIBILITY All materials supplied to this specification must be equivalent in all characteristics to the material upon which approval was originally
17、granted. Prior to making any changes to the material originally approved under this specification, whether or not such changes affect the materials ability to meet the specification requirements, the Supplier shall notify the affected Purchasing, and Materials Engineering activities (with reasons) o
18、f the proposed changes. Upon notification of the Company, further i nstructions will be provided. Note: Suppliers should be prepared to provide test data and samples demonstrating compliance to this specification, if requested. Substance restrictions imposed by regulations or Company direction appli
19、es to the materials addressed by this document. The restrictions are identified in Restricted Substance Management Standard WSS - M99P9999 - A1. ENGINEERING MATERIAL SPECIFICATION ESF-M99G152-A Page 4 of 4 Copyright 2000, Ford Global Te chnologies, Inc. 4. APPROVAL OF MATERIALS Materials defined by
20、this specification for direct supply to the Company must have prior approval. Certa in materials subcontracted by part suppliers may also require prior approval. These include materials critical to the Companys business for regulatory, safety, environmental or compatibility requirements or contractu
21、al agreements. Suppliers desiring app roval of their materials shall first obtain an expression of interest from Purchasing, Design or Materials Engineering activity. Upon request, the Supplier shall submit a completed copy of their laboratory test reports, signed by a qualified and authorize d representative of the test facility, demonstrating full compliance with all the requirements of this specification.
