What is a valve spring? How does it differ from a common spring? Thank you in advance for your cooperation. (Background of question: I work for a design company and I am doing strength calculations for springs. I found out that the allowable shear stress varies depending on the spring material, and this question came up when I was trying to select the appropriate material. Specifically, SWOSC-B and SWOSC-V. (I wondered what a valve spring is, since the JIS specifies that -B is an oil-tempered wire for springs and -V is an oil-tempered wire for valve springs. (I wondered what a valve spring was.)
SWOSC-B and SWOSC-V are listed in the JIS standard with the following steel grades. Oil tempered wire for springs (SWOSC-B)Oil tempered wire for valve springs (SWOSC-V)As for fatigue strength, SWOSC-V, which is manufactured for valve springs of internal combustion engines, is superior. The difference lies in the higher control level of impurities and defects. In terms of chemical composition, the content of “P” and “S” is low, and the depth of defects and decarburization layer are also strictly controlled. Therefore, the probability of fracture is less than SWOSC-B due to fewer material defects that affect fatigue strength, and it can be said that SC-V has superior fatigue strength when fatigue tests are conducted at the same level of stress amplitude. Best regards.
