Thank you for the information about the variation in the production of compression springs.
What is the variation in spring constant due to the manufacture of compression springs? For example, within ± 10%, etc. Is there a specific design value?
Spring Newbie, thank you for your inquiry.
JIS B2704 describes the regulations for spring constants, loads, and variations in dimensions. For cold-formed spring constants, if the deflection% is in the range of 30% to 70% and the number of active coils is 3 to 10 or less, the first grade: ± 5%, and the second grade: ± 10% are applied.
If the number of active coils exceeds 10, the 1st grade: ± 4% and the 2nd grade: ± 8% are applied. Depending on the conditions such as coil mean diameter and height, different variations can be applied.
Therefore, please consult with us at the time of production!!!
Thank you for your reply.
The drawing of a compression coil spring stated that the free length is 10 mm ± 5% (variation ± 2%), and I think that some standard value is written here too, but what does variation ± 2% mean? Is it a calculated value?
Spring Newbie, thank you for your inquiry.
JIS B2704 specifies the tolerance of the free length of cold-formed compression coil springs in the range of ± 1% to ± 6% (* with a minimum value) depending on the shapes. Among them, it seems that ± 5% (± 0.5 mm) was applied. However, the variation within the tolerance (± 2% in this case) is not specified by JIS.
Therefore, for the ± 2% variation, it seems that the designer has set the necessary criteria additionally.
