GB/T 5764-2023Clutch facings for automobiles (English PDF)

4.1 Appearance

4.1.1 The surface of the facing shall be smooth after processing, and there shall be no defects such as blisters, cracks, oil stains, unevenness, warping, and distortion that may affect use.

4.2 Dimensional-deviation The basic dimensions of the facings are shown in Appendix A or determined by the purchaser. The size deviation and thickness difference of each piece shall comply with the provisions of Table 1.

4.3 Flatness The flatness of the facing under the specified load shall comply with the provisions of Table 2.

4.4 Friction property

4.5 Bending property The bending strength and maximum strain of the facings shall comply with the provisions of Table 4.

4.6 Rotate bursting test strength The rotate bursting test strength of the facings under specified acceleration shall comply with the provisions of Table 5.

4.7 Hazardous ingredients

4.7.1 The facings shall not contain asbestos.

5.4.3 Test conditions

5.4.3.1 The pressure of the test piece is 0.49MPa.

5.4.4 Test procedures

5.4.5.1 The coefficient of dynamic friction at each test temperature is calculated according to Formula (1).

5.5.1 Test piece

5.5.1.1 Three test pieces are prepared from the same facing along the friction direction.

5.5.1.2 The thickness of the test piece shall be the thickness of the facing, with a length of 55 mm ±

0.5 mm and a width of 15 mm ±

0.2 mm. If the length of the test piece is less than 55 mm, take 40 mm ±

0.5 mm. When sampling, the grooves in the test piece shall be avoided.

5.5.3 Test procedures

5.5.3.1 The thickness of the test piece shall be measured by a micrometer at three points in the middle; and the arithmetic mean value shall be taken. The width of the test piece shall be measured by a vernier caliper at three points in the middle; and the arithmetic mean value shall be taken.

5.5.3.2 Adjust the distance between the fulcrums according to the test piece.

5.5.3.3 Place the test piece on the fulcrum of the test fixture with the friction surface side facing up.

5.5.5 Expression of results The test results are expressed as the arithmetic mean of the test results of three test pieces, rounded off to one digit after the decimal point.

5.6 Rotate bursting test strength

5.6.1 Test pieces Take 6 complete facings with no defects in appearance quality as test pieces. Among them, 3 test pieces shall be tested at normal temperature and 3 test pieces shall be tested at high temperature. The reference dimension is Phi200mm×Phi134mm×3.5mm (without holes or grooves).

5.6.2 Test equipment The principle of testing equipment of rotate bursting test strength is shown in Figure 1; and the

5.6.3 Test procedures

5.6.3.1 Carry out idle test run first; and use a speedometer to check whether the set speed and angular acceleration are consistent with the test conditions.

5.6.3.2 Select the appropriate test fixture according to the size of the test piece.

5.6.3.3 Install the test piece on the test fixture and press it tightly; close and lock the test chamber.

5.6.4 Test report The limit rotation speed when the test piece rotates on the rotate strength testing machine under normal temperature or high temperature conditions until bursting is the rotate bursting test strength at normal temperature or high temperature; when the test piece reaches the upper limit of the equipment speed and still does not burst, record the upper limit speed as the test result, and indicate not bursting.

5.7 Limits of hazardous ingredients

5.7.1 The determination of asbestos content shall be carried out in accordance with the provisions of GB/T 23263.

6.1 Classification of inspection

6.1.1 Exit-factory inspection The exit-factory inspection items are shown in Table 7.

6.1.2 Type inspection The type inspection items are shown in Table

7.Type inspection shall be carried out when any of the following situations occurs.

6.3 Sampling plan

6.3.1 The appearance, dimensional deviation, and flatness of the facings are inspected by random sampling methods. According to GB/T 2828.1, a normal inspection sampling plan is used; and if the special inspection level is S-4, and the AQL value shall be 4.0.The sample size required for different batches and the determination of qualified or unqualified batches shall comply with the provisions of Table 8.

6.4 Judgment of results

6.4.1 Appearance, dimensional deviation and flatness shall be determined according to Table 8.

6.4.2 Except for 6.4.1, if all other inspection items meet the requirements of this Document, the batch of products shall be judged to be qualified. If any of the above inspection items is unqualified, double samples shall be taken for re-inspection; if the re-inspection results meet the requirements of this Document, the item shall still be judged to be qualified. If there is still one re-inspection result that does not meet the requirements of this Document, the item of this batch of product shall be judged to be unqualified.

7.1 Marking

7.1.1 The non-working surface of the facing shall have the manufacturer's name or trademark, production date or batch number.

7.2 Packaging

7.2.1 The facings shall be packed tightly and neatly into clean, dry, strong and durable packaging boxes.

7.3 Transportation During transportation, the facings shall not be damaged or contaminated by oil or water.