The basic steps of the tensile test:
1. sampling: the sample must come from the test batch of products, and can represent the overall quality level of the batch of products
2. select fixture or tooling: select the appropriate fixture or process equipment for the tension test, can simulate the actual use of lifting products, can be more accurate to measure the test results
3. Installation: Install the specimen on the fixture or tooling, check whether the connection is firm, and take safety measures to ensure personnel safety 4. Apply tension: Apply tension to the specimen according to the test rate and load required by the relevant standards
5. Unloading observation: After unloading at the end of the test, judge the test result according to the deformation or fracture of the specimen.
After the completion of the tensile test, how to judge whether the product meets the standard? The final data of the force on the specimen can judge whether the product is qualified or not? The answer is not so simple.
Guofeng testing engineers of Guofeng Wire Rope Testing Service Center give you an example:
Figure 1: The chain ring after breaking test, the tensile force is 97.8kN, higher than the GB/T 20947 standard requirement of 80.4kN, the breakage is in the arc position of the chain ring, the breakage becomes smaller, there is obvious neck shrinkage phenomenon, the total limiting elongation is measured as 16.5%, which is higher than the standard requirement of 10%, it proves that the chain tensile force and plasticity are up to the standard, so it is judged to be qualified.
Figure 2: The chain ring after breaking test, the tensile force is 87.5 kN, the same is higher than the GB/T 20947 standard requirement of 80.4 kN, but the fracture is in the welded position, there is no obvious neck shrinkage phenomenon, and the total limiting elongation is 7.0%, which is not up to the standard requirement, although the tensile force of the chain is up to the standard, but the plasticity of the chain is not up to the standard, so it is judged to be unqualified.
How Tensile Testing Helps Quality Control
Tensile testing machine is used to measure the tensile test results by applying load to the product axially, which is an essential testing equipment for quality control, product development and so on. Choosing the right test equipment not only improves work efficiency, but also obtains test results more accurately. Tensile test through the product of raw materials sampling, production process, finished product sampling several links to verify, can ensure that the product quality is qualified. This is mainly reflected in three points:
Product accessories or raw materials should be sampled for tensile strength test, the test results are qualified that into the warehouse; the results are unqualified by no means into the warehouse.
Product accessories or raw materials into the warehouse after the production of the first product, and then the tensile test, the results can be qualified for mass production, the results are unqualified that is to improve the process, until the tensile test is qualified.
After the completion of product production, according to the relevant product standards on the finished product sampling, tensile strength test, the test results are qualified before shipment.
