1 Scope
This document specifies the test conditions and preparation, specimen items and procedures, and test reports for the shrinkage ratio bench test method of brake lining friction materials for road vehicles.
This document applies to the shrinkage bench test of disc brake linings for passenger cars. On the basis of familiarity with the principle of shrinkage, brake lining tests for other types of vehicles can also refer to this document. This document applies to the screening and inspection of raw materials, the early development of friction materials, the quality control of the production process and the testing of external samples.
2 Normative references
There are no normative references in this document.
3 Terminology and definitions
The following terms and definitions are applicable to this document.
3.1 Scaling factor
4 Symbols and abbreviations
The following symbols and abbreviations apply to this document (see Table 1).
5 Test conditions and preparation
5.1 Test conditions
5.1.1 Test equipment
Scaling inertia test rig, see Appendix A for technical parameters.
5.1.2 Brake line pressure creep rate
In addition to the test with pressure creep rate requirements, all braking loading, pressure rise rate of (25 Shi 5) MPa / s.
5.1.3 Maximum brake line pressure
The maximum braking pressure of the brake loading system of the scale down test rig shall not be less than 20 MPa.
5.1.4 Acquisition frequency
The collection frequency of braking pressure and braking torque is not less than 100 Hz, and the sampling frequency can be adjusted according to the standard requirements.
5.1.5 Cooling air conditions - wind speed
The cooling air speed is l m/s for the recession tests (6.6 and 6.8) and ll m/s for the rest of the tests and can be adjusted according to the different test standards.
5.1.6 Test environment control conditions - temperature and humidity requirements
During the shrinkage test, the temperature and relative humidity of the cooling air should be regulated and controlled, and the average value of the temperature, relative humidity and cooling air speed should be measured and recorded during each braking process.
The technical parameters of the environmental control system are shown in Appendix B.
Note: In general, the control range of the cooling air is: 20 ℃ ~ 25 ℃, relative humidity: 60% -65%.
5.1.7 Speed between brakes
During the cooling period between brakes, the test stand is rotated at a speed of 10 km/h. For the recession test, the waiting speed is the initial speed of the next brake.
5.1.8 Initial braking temperature
The initial braking temperature is the real time temperature of the brake disc at the start of braking.
5.1.9 Test temperature measurement
A small 3.0 mm hole is drilled in the centre of the brake disc thickness and a type K thermocouple is buried at the effective friction radius, see Appendix C.
5.1.10 Sensor calibration
The sensors for measuring speed, temperature, pressure, torque, cooling air speed and temperature and humidity are calibrated annually by a third party metrologist and a calibration certificate is issued. The measurement system can be verified and documented by the user on a regular basis according to the test conditions.
5.1.11 Sample measurements
The thickness and mass of the test specimen and brake disc are measured before and after the test to calculate the thickness wear and mass wear during the test, see Appendix D for measurement locations.
5.1.12 Data acquisition
The following data are to be collected automatically and in real time during the test on the shrinkage inertia test rig:
Braking time;
Spindle speed;
Braking line pressure;
Braking torque;
Brake disc temperature;
Cooling air temperature;
Cooling air velocity;
Relative humidity of the cooling air;
Test procedure and number of brakes.
6 Test items and procedures
6.1 Pre-combustion inspection
The pre-break-in check is carried out under the following test conditions:
a) Initial braking speed: 50 km/ h;
b) initial brake temperature (first brake): <40 °C;
c) Braking deceleration 0.3 g ;
Note, g in this document is the acceleration of gravity.
d) Braking cycle; 120 s;
e) Number of braking cycles:10.
6.2 First (pre-break-in) efficiency test
The first (pre-break-in) efficiency test is carried out according to the test conditions:
a) Initial braking speed: 50 km/ h. 100 km/ h;
b) Initial braking temperature: 80 °C;
c) brake deceleration: 0.1g ~ 0.8g; d brake times: 16 (2 x 8) times.
Note 1: Both the braking initial speed and braking or speed are tested in the order of scoop from low to high.
Note 2: For each initial braking speed, the braking deceleration is increased from low to high in 0.lg increments, from 0.lg to 0.8g.
Note 3: In accordance with the above requirements, all braking in this document is done using constant output (constant torque) braking, if constant input (constant pressure) braking is used, this is to be recorded.
6.3 Break-in test
The break-in test is carried out under the following test conditions:
a) initial braking speed; 65 km/h;
b) initial brake temperature: 120 ℃; c) brake deceleration: 0.35g number of brakes; 200 times.
Note, after 200 times of break-in, the contact rate of the break-in surface should be checked, and the requirement is not less than 80%. If the requirement is not met, increase the number of break-in cycles.
6.4 Second efficiency test
Repeat the first performance test (6.2), but with changes to the initial braking speed and number of brakes:
a) Initial braking speed: 20 km/ h, 50 km/h. 10o km/ h, 130 km/ h;
b) Initial braking temperature: 80 °C;
c) brake deceleration: 0.1g-0.8g; braking times: 32 (4X8) times.
6.5 First re-break-in
Repeat 6.3 break-in test, but with 35 braking cycles.
6.6 First recession recovery test
6.6.1 Baseline test
6.7 Second re-break-in
Perform the test according to 6.5.
6.8 Second recession recovery test
Repeat the test as required in 6.6, except that the number of braking cycles for the recession test is 15.
6.9 Third re-break-in
Repeat the test in accordance with 6.5.
6.10 Third effectiveness test
Repeat the test according to 6.4.
6.11 Post-test measurements and checks
6.11.1 `Post-test measurements of the sample and disc are shown in Appendix D. Calculate thickness wear and mass wear to three decimal places.
6.11.2 Check and record (photograph) the surface condition of the sample and brake disc, and take photographs.
7 Test report
7.1 Overview
The way in which the test results are reported and what is of interest depends on the purpose of the test for the user, and the test report can be divided into tabular and graphical reports.
7.2 Tables
7.2.1 Test information
This includes at least: test date, material, simulated model and brake parameters, test specification, test inertia, shrinkage ratio and test ambient conditions (cooling air temperature and humidity settings).
7.2.2 Test data
7.2.2.1 The data to be included in the table for each brake include: test number, initial brake speed and release speed, brake line pressure, brake torque, coefficient of friction, initial brake disc temperature and final brake temperature, brake time. Braking distance, braking deceleration and MFDD; where: torque, pressure, coefficient of friction to include the maximum, minimum and average values.
7.2.2.2 According to the purpose of the test, it is also possible to calculate and list; brake line pressure and brake torque stability coefficient, specific brake torque, and other data that the tester needs to know.
7.2.3 Summary table of test results
The contents of the summary table can be selected and processed from the test data according to the requirements of the tester or the customer:
The average coefficient of friction; the average of the coefficients of friction for different test steps or for the whole process;
Friction values at key points: key points in the performance test, minimum friction coefficient in the recession test, etc.
Braking temperature at critical points: maximum disc temperature (end temperature) in the recession test, etc;
Wear data: thickness wear and mass wear of inner pads, outer pads and discs (in tabular form).
7.3 Graphical report
The form of the graphical report depends on the purpose of the test and the requirements of the customer, but a graphical plot of the coefficient of friction and temperature variation including each brake application is a basic requirement.
7.4 Examples of reports
Examples of reports are given in Appendix G.
Appendix A (informative) Technical parameters of the scaled-down inertia test rig
Appendix B (informative) Technical conditions for the shrinkage test cooling air (environmental control system)
Appendix C (informative) Temperature measurement methods for the shrinkage test
Appendix D (informative) Wear measurement of brake linings and brake discs
Appendix E (informative) Technical conditions for scaled-down brake discs
Appendix F (informative) Outline of the shrinkage test
Appendix G (informative) Example of test report format
Bibliography
1 Scope
2 Normative references
3 Terminology and definitions
4 Symbols and abbreviations
5 Test conditions and preparation
6 Test items and procedures
7 Test report
Appendix A (informative) Technical parameters of the scaled-down inertia test rig
Appendix B (informative) Technical conditions for the shrinkage test cooling air (environmental control system)
Appendix C (informative) Temperature measurement methods for the shrinkage test
Appendix D (informative) Wear measurement of brake linings and brake discs
Appendix E (informative) Technical conditions for scaled-down brake discs
Appendix F (informative) Outline of the shrinkage test
Appendix G (informative) Example of test report format
Bibliography
1 Scope
This document specifies the test conditions and preparation, specimen items and procedures, and test reports for the shrinkage ratio bench test method of brake lining friction materials for road vehicles.
This document applies to the shrinkage bench test of disc brake linings for passenger cars. On the basis of familiarity with the principle of shrinkage, brake lining tests for other types of vehicles can also refer to this document. This document applies to the screening and inspection of raw materials, the early development of friction materials, the quality control of the production process and the testing of external samples.
2 Normative references
There are no normative references in this document.
3 Terminology and definitions
The following terms and definitions are applicable to this document.
3.1 Scaling factor
4 Symbols and abbreviations
The following symbols and abbreviations apply to this document (see Table 1).
5 Test conditions and preparation
5.1 Test conditions
5.1.1 Test equipment
Scaling inertia test rig, see Appendix A for technical parameters.
5.1.2 Brake line pressure creep rate
In addition to the test with pressure creep rate requirements, all braking loading, pressure rise rate of (25 Shi 5) MPa / s.
5.1.3 Maximum brake line pressure
The maximum braking pressure of the brake loading system of the scale down test rig shall not be less than 20 MPa.
5.1.4 Acquisition frequency
The collection frequency of braking pressure and braking torque is not less than 100 Hz, and the sampling frequency can be adjusted according to the standard requirements.
5.1.5 Cooling air conditions - wind speed
The cooling air speed is l m/s for the recession tests (6.6 and 6.8) and ll m/s for the rest of the tests and can be adjusted according to the different test standards.
5.1.6 Test environment control conditions - temperature and humidity requirements
During the shrinkage test, the temperature and relative humidity of the cooling air should be regulated and controlled, and the average value of the temperature, relative humidity and cooling air speed should be measured and recorded during each braking process.
The technical parameters of the environmental control system are shown in Appendix B.
Note: In general, the control range of the cooling air is: 20 ℃ ~ 25 ℃, relative humidity: 60% -65%.
5.1.7 Speed between brakes
During the cooling period between brakes, the test stand is rotated at a speed of 10 km/h. For the recession test, the waiting speed is the initial speed of the next brake.
5.1.8 Initial braking temperature
The initial braking temperature is the real time temperature of the brake disc at the start of braking.
5.1.9 Test temperature measurement
A small 3.0 mm hole is drilled in the centre of the brake disc thickness and a type K thermocouple is buried at the effective friction radius, see Appendix C.
5.1.10 Sensor calibration
The sensors for measuring speed, temperature, pressure, torque, cooling air speed and temperature and humidity are calibrated annually by a third party metrologist and a calibration certificate is issued. The measurement system can be verified and documented by the user on a regular basis according to the test conditions.
5.1.11 Sample measurements
The thickness and mass of the test specimen and brake disc are measured before and after the test to calculate the thickness wear and mass wear during the test, see Appendix D for measurement locations.
5.1.12 Data acquisition
The following data are to be collected automatically and in real time during the test on the shrinkage inertia test rig:
Braking time;
Spindle speed;
Braking line pressure;
Braking torque;
Brake disc temperature;
Cooling air temperature;
Cooling air velocity;
Relative humidity of the cooling air;
Test procedure and number of brakes.
6 Test items and procedures
6.1 Pre-combustion inspection
The pre-break-in check is carried out under the following test conditions:
a) Initial braking speed: 50 km/ h;
b) initial brake temperature (first brake): <40 °C;
c) Braking deceleration 0.3 g ;
Note, g in this document is the acceleration of gravity.
d) Braking cycle; 120 s;
e) Number of braking cycles:10.
6.2 First (pre-break-in) efficiency test
The first (pre-break-in) efficiency test is carried out according to the test conditions:
a) Initial braking speed: 50 km/ h. 100 km/ h;
b) Initial braking temperature: 80 °C;
c) brake deceleration: 0.1g ~ 0.8g; d brake times: 16 (2 x 8) times.
Note 1: Both the braking initial speed and braking or speed are tested in the order of scoop from low to high.
Note 2: For each initial braking speed, the braking deceleration is increased from low to high in 0.lg increments, from 0.lg to 0.8g.
Note 3: In accordance with the above requirements, all braking in this document is done using constant output (constant torque) braking, if constant input (constant pressure) braking is used, this is to be recorded.
6.3 Break-in test
The break-in test is carried out under the following test conditions:
a) initial braking speed; 65 km/h;
b) initial brake temperature: 120 ℃; c) brake deceleration: 0.35g number of brakes; 200 times.
Note, after 200 times of break-in, the contact rate of the break-in surface should be checked, and the requirement is not less than 80%. If the requirement is not met, increase the number of break-in cycles.
6.4 Second efficiency test
Repeat the first performance test (6.2), but with changes to the initial braking speed and number of brakes:
a) Initial braking speed: 20 km/ h, 50 km/h. 10o km/ h, 130 km/ h;
b) Initial braking temperature: 80 °C;
c) brake deceleration: 0.1g-0.8g; braking times: 32 (4X8) times.
6.5 First re-break-in
Repeat 6.3 break-in test, but with 35 braking cycles.
6.6 First recession recovery test
6.6.1 Baseline test
6.7 Second re-break-in
Perform the test according to 6.5.
6.8 Second recession recovery test
Repeat the test as required in 6.6, except that the number of braking cycles for the recession test is 15.
6.9 Third re-break-in
Repeat the test in accordance with 6.5.
6.10 Third effectiveness test
Repeat the test according to 6.4.
6.11 Post-test measurements and checks
6.11.1 `Post-test measurements of the sample and disc are shown in Appendix D. Calculate thickness wear and mass wear to three decimal places.
6.11.2 Check and record (photograph) the surface condition of the sample and brake disc, and take photographs.
7 Test report
7.1 Overview
The way in which the test results are reported and what is of interest depends on the purpose of the test for the user, and the test report can be divided into tabular and graphical reports.
7.2 Tables
7.2.1 Test information
This includes at least: test date, material, simulated model and brake parameters, test specification, test inertia, shrinkage ratio and test ambient conditions (cooling air temperature and humidity settings).
7.2.2 Test data
7.2.2.1 The data to be included in the table for each brake include: test number, initial brake speed and release speed, brake line pressure, brake torque, coefficient of friction, initial brake disc temperature and final brake temperature, brake time. Braking distance, braking deceleration and MFDD; where: torque, pressure, coefficient of friction to include the maximum, minimum and average values.
7.2.2.2 According to the purpose of the test, it is also possible to calculate and list; brake line pressure and brake torque stability coefficient, specific brake torque, and other data that the tester needs to know.
7.2.3 Summary table of test results
The contents of the summary table can be selected and processed from the test data according to the requirements of the tester or the customer:
The average coefficient of friction; the average of the coefficients of friction for different test steps or for the whole process;
Friction values at key points: key points in the performance test, minimum friction coefficient in the recession test, etc.
Braking temperature at critical points: maximum disc temperature (end temperature) in the recession test, etc;
Wear data: thickness wear and mass wear of inner pads, outer pads and discs (in tabular form).
7.3 Graphical report
The form of the graphical report depends on the purpose of the test and the requirements of the customer, but a graphical plot of the coefficient of friction and temperature variation including each brake application is a basic requirement.
7.4 Examples of reports
Examples of reports are given in Appendix G.
Appendix A (informative) Technical parameters of the scaled-down inertia test rig
Appendix B (informative) Technical conditions for the shrinkage test cooling air (environmental control system)
Appendix C (informative) Temperature measurement methods for the shrinkage test
Appendix D (informative) Wear measurement of brake linings and brake discs
Appendix E (informative) Technical conditions for scaled-down brake discs
Appendix F (informative) Outline of the shrinkage test
Appendix G (informative) Example of test report format
Bibliography
Contents of GB/T 41663-2022
1 Scope
2 Normative references
3 Terminology and definitions
4 Symbols and abbreviations
5 Test conditions and preparation
6 Test items and procedures
7 Test report
Appendix A (informative) Technical parameters of the scaled-down inertia test rig
Appendix B (informative) Technical conditions for the shrinkage test cooling air (environmental control system)
Appendix C (informative) Temperature measurement methods for the shrinkage test
Appendix D (informative) Wear measurement of brake linings and brake discs
Appendix E (informative) Technical conditions for scaled-down brake discs
Appendix F (informative) Outline of the shrinkage test
Appendix G (informative) Example of test report format
Bibliography
