1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW16394 Brake Rotors - Gray Cast Iron Copyright 2013 General Motors Company All Rights Reserved June 2013 Page 1 of 20 1 Scope Note: Nothing in this standard supercedes applicable laws and regulations. Note: In the event of conflict between th
2、e English and domestic language, the English language shall take precedence. 1.1 Material Description. Gray cast iron. 1.2 Symbols. Not applicable. 1.3 Typical Applications. This standard specifies material and product requirements for all unventilated and ventilated brake disks for automotive indus
3、tries. The gray iron rotors are specified by chemistry, mechanical properties, microstructures and quality requirements. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM A48 ASTM E322 ISO 185 ISO 6506 ASTM A2
4、47 ASTM E1019 ISO 945 ISO 6892 2.2 GM Standards/Specifications. GMW3059 GMW16218 GMW16369 GMW15632 GMW16284 2.3 Additional References. TMC003 Material Safety Data Sheet guidance documents (available at ). 3 Requirements 3.1 Material. Unalloyed and low alloyed gray cast iron with predominantly Type A
5、 graphite and pearlitic matrix shall be used for brake rotors. 3.2 Chemical Composition. The casting producer shall measure chemical compositions for all elements except carbon, with samples taken from the melt and solidified in a metallic chill die. Spectrographic analysis of chemistry shall be mea
6、sured in accordance with procedures, master samples and calibration per ASTM E322. Carbon levels shall be measured using either thermal analysis or C and S analyzer, and shall be measured in accordance with procedures, master samples and calibration per ASTM E1019. The compositions listed in the tab
7、les reflect those of finished castings. Additional care should be taken to understand the silicon levels of parts that utilize late process inoculation. When using optical emission spectroscopy to analyze a finished casting for chemical composition, a piece of the casting shall be remelted so a chil
8、led sample is obtained. 3.2.1 Chemical Composition Initial Selection. The desired chemical compositions for various grades are listed in Table 1. During initial design stages, the supplier should develop an aim chemical composition to achieve the mechanical properties per Table 1. The chemical compo
9、sitions in Table 1 are typical and considered secondary to the mechanical properties, with the exception of the carbon equivalent (CE) which is mandatory. The aim chemistry for validation samples should take into account that production parts will need Copyright General Motors Company Provided by IH
10、S under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16394 Copyright 2013 General Motors Company All Rights Reserved June 2013 Page 2 of 20 to be produced with minimal variation from the va
11、lidation samples. The stated minimum Chromium levels for grades G205SP-R1 and G250SP-R1 are mandatory. The global grades are given in Table 1 and the regional grade relationship is indicated in Table 2. Table 1: Gray Cast Iron for Integral Hub and Disc Castings and Disc Brake Rotors GMW16394 Grades
12、G135SP-R1 Note 1 G180SP-R1 Note 1 G205SP-R1 Note 2 G250SP-R1 Mandatory Mechanical Properties Ultimate Tensile Strength, Minimum, Rm N/mm2 135 180 205 250 Wedge Compression Strength, Rmk N/mm2 110 minimum 140 minimum 145 minimum N/A Hardness Note 3 HBW 156 to 207 183 to 223 187 to 229 197 to 235 Diff
13、erence in HBW at Friction Surface, 15 Increments, (HBW) Note 4 HBW 15 max. 15 max. 15 max. 15 max. Acceptable Microstructure See Table A1 Chemical Composition Note 5 Carbon Equivalent (CE) Note 6 (Mandatory) % by mass 4.30 to 4.60 4.10 to 4.40 3.90 to 4.30 3.80 to 4.20 Carbon 3.65 to 3.95 3.65 to 3.
14、95 3.20 to 3.50 3.10 to 3.40 Silicon 1.75 to 1.95 1.00 to 1.30 1.90 to 2.40 1.90 to 2.40 Manganese 0.50 to 0.80 0.50 to 0.80 0.45 to 0.90 0.60 to 0.90 Sulfur 0.12 max. 0.12 max. 0.12 max. 0.12 max. Phosphorus 0.10 max. 0.10 max. 0.10 max. 0.1 max. Chromium Note 7 0.25 max. 0.25 max. 0.15 to 0.40 0.2
15、5 to 0.40 Copper 0.40 max. 0.60 max. 0.60 max. 0.60 max. Tin 0.07 max. 0.07 max. 0.07 max. 0.07 max. Note 1: These grades are used for brake rotors requiring exceptional damping properties. Note 2: A variation of this is a low alloyed grade G205SP-R1-A, with copper 0.40 to 0.55% and chromium 0.40 to
16、 0.55%. The stated minimums for copper and chromium are mandatory. Note 3: Hardness indicated is on finish machined surface of casting. Cast surface hardness may be higher. Note 4: Measured on friction surface every 15 degrees with a 5 mm ball and a 750 kg load (see Appendix A, Data Sheet A2 for rep
17、orting format). Note 5: Chemical composition is typical, however carbon equivalent is mandatory. Note 6: Carbon equivalent, CE = C% + (Si% + P%)/3. Note 7: The stated minimums for chromium are mandatory. Table 2: Relationships of Global Grades to Regional Grades Global Grade Equivalent Grades Relate
18、d Grades GMW16394-IR-C-G135SP-R1 GME 05002 Type D GMW16394-IR-C-G180SP-R1 GME 05002 HCLSi GMW16394-IR-C-G205SP-R1 GMB EMS 374 GME 05002 Type E GMW16394-IR-C-G250SP-R1 GME 05002 Types A and B Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo re
19、production or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16394 Copyright 2013 General Motors Company All Rights Reserved June 2013 Page 3 of 20 3.2.2 Restriction of Composition. All rotors are expected to be produced with the same alloying system as valid
20、ation samples. To show compliance to this the levels of CE, C, Si, Mn, Cu, Sn, Cr and will be restricted to the ranges listed in Table 3. The supplier is to develop maximum and minimum limits that adhere to these ranges. 3.2.3 Documentation of Restricted Composition. The supplier shall document, pri
21、or to delivery of castings, the limits on chemical composition that shall be controlled in production. The restricted ranges that are chosen for these elements shall be documented in the GM engineering drawing and other equivalent part specification documents. The restricted composition shall also b
22、e reported in Production Part Approval Process (PPAP) documents as indicated in Appendix A, Data Sheet A1. Table 3: Gray Cast Iron Composition Restriction Ranges Element Restricted Composition Range Note 1 Primary Effect of Element (Informative) Carbon Equivalent (CE) % by Mass (Calculated) 0.30 Vol
23、ume of graphite, Youngs Modulus and Frequency Response Function (FRF) Carbon % by Mass 0.30 Graphitizer Silicon % by Mass 0.30 Graphitizer Manganese % by Mass 0.30 Produces MnS for machinability, Pearlite stabilizer Copper % by Mass 0.15 Pearlite stabilizer, (graphitizer) Tin % by Mass 0.040 Pearlit
24、e stabilizer (carbide stabilizer) Chromium % by Mass 0.15 Pearlite stabilizer (carbide stabilizer) Phosphorous % by Mass 0.030 Produces Phosphide eutectic Sulphur % by Mass 0.040 Produces MnS for Machinability Note 1: Range is the difference between agreed upon maximum and minimum. 3.3 Tensile Stren
25、gth and Hardness. 3.3.1 Tensile Strength. The ultimate tensile strength specified for rotors shall be measured and met by taking test pieces machined from the brake surfaces of the castings. The specified tensile strength requirements shall be determined by a statistically significant sampling of te
26、st pieces that were machined from castings. The mechanical properties shall meet or exceed the minimum product requirements. Irrespective of the sampling frequency used by the supplier, all parts are expected to meet the requirements. The standard dimensions and testing procedure for test samples an
27、d machined test pieces are described in the ISO 185 and ISO 6892. The validity of tests and applicability of any retests shall be in accordance with ISO 185. It is preferred to use a round specimen. When a round specimen is not practical a flat specimen may be used. An alternate to tensile test usin
28、g flat specimen is Wedge Compression test (as described by the VDG P340 specification using an adaptive fixture described or equipment by Feinmechanik Ralf Kogel, Germany, and Instrument for wedge-type compression tests KDG 3/30). A specimen size of 50Lx20Wx6.5T (mm) is supported in between two oppo
29、sed knife edges at 40 mm apart. The specimen size is somewhat arbitrary and the overall length is governed by the host casting and the capacity of the testing unit frame. The specimen length allows several comparison tests to be performed in order to improve variability. The conversion equation tabu
30、lated below shall be considered valid for specimens between 6 mm and 7 mm in thickness. A force is applied at its midpoint and the fracture load is measured. The wedge compression strength (Rmk) is computed by dividing the fracture load with the area of cross section of the specimen. Tensile strengt
31、h correlates with wedge compression strength by: Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16394 Copyright 2013 General Motors Comp
32、any All Rights Reserved June 2013 Page 4 of 20 For compliance purpose the tensile strength is reported by testing an excised test coupon from castings. However, the casting producer may use a separately cast test bar per ISO 185 or ASTM A48 to assess the quality of the material and melt from which t
33、he casting is poured. The properties of the pieces machined from the castings may vary from those machined from separately cast test samples because of cooling rate and section size variations and the variance in the method of making the separately cast test bar. Porosity, shrink or other discontinu
34、ities within a test piece represents an invalid test, thus the data shall be discarded. The viewing of such discontinuities shall be done without the use of any magnifying device. If a test specimen fails to meet a specific tensile requirement for an unknown reason, two more retests can be run from
35、the same material. If both retest pieces pass the tensile requirement, the material will be deemed acceptable. 3.3.2 Hardness. Brinell hardness shall be taken in accordance with ISO 6506. The hardness shall be met on finish machined castings. For day-to-day foundry process control, the casting surfa
36、ce hardness is usually measured. To prepare the casting for load impression a representative depth of 1 mm shall be removed from the surface. A smooth surface shall be established to improve the measurement accuracy. The hardness on the un-machined rotor surface may be higher. When the foundry measu
37、res casting surface hardness for day-to-day foundry process control, a correlation shall be established between the finish machined and as-cast surface hardness. In unusual cases where the specified hardness and tensile strength cannot be met simultaneously, a revised hardness range shall be establi
38、shed by agreement between the purchaser and supplier based on measurements of the finish machined rotors. The tensile strength will take precedence over hardness. 3.3.2.1 For optimum rotor performance the hardness variation on the rotor surface shall be kept to a minimum. The variation on any one br
39、ake surface (in board or out board) shall be a maximum of 15 HBW. To comply with this requirement the hardness shall be measured on 3 selected diameters, at 15 degree increments on a brake friction surface as indicated in Figure 1. The 3 selected diameters shall coincide with the inner diameter (ID)
40、, mid-point and outer diameter (OD) of the pad contact surface on the rotor. It is the expectation of the buyer that the casting supplier will adopt suitable gating and risering techniques to produce rotors with the required uniform hardness. The hardness variation test measurements shall be perform
41、ed for initial tooling and process validation. The 15 BHW maximum variation for the specific brake surface shall be demonstrated through PPAP. The measurement surface must be machined to the machined rotor dimensions and polished with 220 grit paper or finer to achieve the required accuracy. The ind
42、entation diameter shall be measured to minimum accuracy of 0.02 mm ( 0.5% of diameter of indentation per ISO 6506-2). To improve the measurement accuracy, the measurement equipment should have better Gauge Repeatability and Reproducibility capability. The measurement shall start from the Riser/Flow-
43、off contact position designated as the zero degree/12 oclock position of the rotor. The casting supplier must provide a permanent cast mark which is preserved on the machined rotor indicating the Riser/Flow-off contact position. The measurements are done every 15 on a diameter near ID mid-point and
44、near OD of each of the in board and out board brake surfaces as indicated in the attached sketch. The recommended procedure requires the use of a 5 mm diameter ball and a 750 kg load for measurement. In the case of vented rotors, the measurement shall be done as close to the joining ribs as possible
45、 to provide firm support for accurate measurement (especially when a 10 mm diameter ball and a 3000 kg load is used due to equipment availability). Due to rib spacing, one may not be able to hold the 15 increment requirement exactly, and in such cases, the measurement shall be done at the nearest 15
46、 interval. The hardness reporting format is indicated in Appendix A, Data Sheet A2. Note: The uniformity measurement may be done at the foundry before stress relieving if used. 3.4 Microstructure. The required microstructure for various grades of rotors is indicated in Table 4. The microstructure sh
47、all consist of predominantly Type A flake graphite (as described in ISO 945) in a matrix of pearlite. Quantitative metallography shall treat graphite and matrix separately such that the total of fractions of each graphite flake type (A, B, C, D, and E) shall equal 100% and total of fractions of each
48、 matrix phase (e.g., ferrite, pearlite, carbide, Steadite, etc.,) shall equal to 100%. The microstructure reporting format is indicated in Appendix A, Data Sheet A3 and Table A1. 3.5. Frequency Response Function (FRF). FRF expresses the rotor structural response to an applied force as a function of
49、frequency. FRF helps to identify at what excitation frequency of an applied force coincide with Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16394 Copyright 2013 General Motors Company All Rights Reserved June 2013 Page 5 of 20 the natural frequency of rotor causing the r
