(1) Cracks in car springs are mainly caused by material manufacturing. The cracks are extended along the pull direction, and the depth can be vertically distributed from several millimeters to more than 1 mm. The rupture material cannot be used to make spring.
(2) If the impurities on the oxide or material rough are removed properly, the surface of the material will feel rough and uneven on the surface of the material. Sometimes the spikes will pierce the fingers. After the spring, you will find the surface of the spring or wrinkles. Materials with severe scaling cannot be used to make spring. When the local scales are rolled into a local scales, it is necessary to remove it. The slight material can be cleaned with a blasting. For materials with local scale, you can consider unimportant spring.
(3) The scratching and drawing of the car spring are mainly caused by the mold holes during the depth of the depth. The rough surfaces of rolling, guide silk board, top rod and other tools are drawn on the spring surface when the spring roll. The stretching direction of raw materials is generally distributed. For springs that do not exceed the tolerance of steel wires that are scratched and pull -out, it is not advisable to create high fatigue performance springs, such as valve spring, plunger spring, etc.
(4) Most of the concave pits when pulling are impurities or oxide on the surface of the steel wire, and then fall off to form a pit. For some parts with concave pits, spring on the surface should be cleared after rolling is rolled. Wide -distributed materials are not used in the manufacture of spring.
(5) The cause of the corrosion of automobile spring is that the material is not rusted before the factory, and the other may be caused by improper storage. Slight rusty materials can be polished with sandpaper. If there is no obvious corrosion pit, you can use it. If there is a corrosion pit, it is not used to make spring.
(6) Send pattern, also known as hair pattern, shallow depth, and severe cracks. Visually, the surface of the material has filaments, and you can tear it off by hand. The hair material is not used to make spring.
(7) This kind of wire is touched by hand, and it can obviously feel uneven thickness, similar to bamboo. Most of these defects are produced during the brushes, among which fine steel wires are the most common. Bullet steel wire affects the process performance of the spiral spring, which causes the internal and external diameter of the spiral spring to control the unstable inner and outer diameter of the spiral spring, affecting the spring load. Therefore, for spring, bamboo steel wires are not required for spring and external diameter and load requirements. Springs with low internal and outer diameter requirements and no load requirements can be considered.