FZ/T 54023-2009Polyamide 66 industrial filament yarns for air bag (English PDF)

6.4 Determination of dry heat shrinkage

6.4.1 Test conditions

6.4.1.1 Dry heat shrinkage tester: a device with temperature indication and time

recording, and capable of recording the shrinkage and shrinkage force of the specimen.

6.4.1.2 Laboratory samples: 20 pieces, each sample is tested once.

6.4.1.3 Heated length of the specimen: according to the model of the instrument heating plate, the length is accurate to ±1.0 mm.

6.4.1.4 Heat treatment temperature: (180 ± 3) °C.

6.4.1.5 Heat treatment time: (120 ± 10) s.

6.4.1.6 Pre-tension: (0.050 ± 0.005) cN/dtex.

6.4.2 Test steps

6.4.2.1 After extracting the surface wire of a laboratory sample, place it under the standard atmospheric conditions specified in 6.1.1 to condition the humidity for at least

16 h.

6.4.2.2 Cut a specimen wire that is suitable for the length of the heating plate from the surface of the laboratory sample after humidity adjustment, hang it for another 3 h under the standard atmospheric conditions specified in 6.1.1 as the specimen to be tested.

6.4.2.3 Adjust the heat treatment temperature, time and pre-tension of the instrument to

meet the requirements of 6.4.1.

6.4.2.4 Fix one end of the specimen to be tested on the specimen holder of the instrument, add a pre-tensioned weight to the other end through a rotating guide pulley, avoid changing the twist of the specimen during the operation.

6.4.2.5 Click the test button, and the instrument heating plate automatically enters the

specimen holder. After the specified test time is reached, the instrument heating plate automatically returns to the initial position. The instrument records the heat shrinkage value after heat treatment, and then takes out the tested specimen.

6.4.2.6 Calculate the test results.

6.4.3 Calculation

The dry heat shrinkage is calculated according to formula (1) and formula (2):

6.7.5 Record the results.

7.1 Inspection type

Both physical performance and appearance quality requirements are factory-exit inspection items.

7.2 Inspection items

Physical performance indicators are inspected according to the items specified in Table

1, and appearance quality requirements are inspected bobbin by bobbin according to the items specified in Table 2.

7.3 Batch rules

Periodic sampling is used within a certain range to form a test batch. A product batch can be composed of one test batch or several test batches.

7.4 Sampling regulations

7.4.1 All appearance items are inspected.

7.4.2 Laboratory samples of physical performance items shall be sampled according to the provisions of GB/T 6502.

7.4.3 The damaged roll packages shall not be sampled.

7.5 Comprehensive evaluation

7.5.1 The measured or calculated values of the physical performance test items shall be compared with the index limit values in Table 1 according to the rounded off value comparison method in GB/T 8170 to evaluate the grade.

7.5.2 The appearance test items shall be compared with the requirements of Table 2 after inspection in accordance with 6.7 and evaluated bobbin by bobbin.

7.5.3 Products that meet the qualified product requirements of 7.5.1 and 7.5.2 at the same time shall be judged as qualified products. If one of the performance does not meet the qualified product requirements of 7.5.1 or 7.5.2, they shall be judged as unqualified products.

8.1 General rules

Within three months after a batch of products arrives at the consignee, a re-inspection may be requested for acceptance or if there is any objection to the quality. If more than one-third of the quantity of the batch of products has been used, re-inspection shall not be applied. If the quality of the batch of products affects the quality of the post- processing products and causes serious losses, the supply and demand parties shall analyze the reasons, clarify the responsibilities, and negotiate to deal with it.

8.2 Inspection items

Same as 7.2.

8.3 Batch regulations

Batch according to product batches.

8.4 Sampling regulations

8.4.1 Appearance is a sampling inspection. According to the batch size, the sample size (code) is determined according to the general inspection level II in Table 1 of GB/T

2828.1-2003.

8.4.2 Laboratory samples of physical performance inspection items are sampled for inspection according to 7.4.2.

8.5 Comprehensive evaluation

8.5.1 Appearance is based on the sample size of 8.4.1, and then according to the acceptance quality level AQL value of 4.0 in the “normal inspection single sampling plan” in Table 2-A of GB/T 2828.1-2003, determine the qualified acceptance number

Ac and the unqualified rejection number Re. According to the provisions of 5.3, if the number of unqualified roll packages is <= Ac, it is judged as qualified; if the number of unqualified roll packages is >= Re, it is judged as unqualified.

8.5.2 The physical performance test items are graded according to the provisions of 5.2.

8.5.3 The grade of the product batch is comprehensively assessed according to the grades of 8.5.1 and 8.5.2. If it meets the qualified product requirements of 8.5.1 and

8.5.2 at the same time, it is judged as qualified; if it does not meet the qualified product requirements of 8.5.1 or 8.5.2, it is judged as unqualified.

9.1 Marking

9.1.1 Product label: each product has a product label inside the bobbin, which identifies the product category, production time, and production location.

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