What tolerances does a standard compression spring have?
The different series follow different standards.
The properties of the wire material and production methods mean that dimensions and the physical constants can vary from production to production, which are all parameters that have an impact on the function of the compression spring. Therefore, a number of parameters have been set up in the range of standard springs.
Series A is all springs with 5 digits in the item number. E.g. 12200
The standard series itself is based on a number of selected wire thicknesses (d) and mean diameters (Dm) plus flexible coils (n). The end force (Fn) and free length (Lo) are values for guidance only.
These dimensions are defined in DIN 2098.
Mean diameter (Dm) tolerances are according to DIN 2095 (Grade 2)
In series A the combination of wire thickness (d) & mean diameter (Dm) & number of flexible coils (n) are the determining parameters. In order to achieve force (Fn) at (Ln) in the best possible way, you can adjust the free length (Lo).
As the free length (Lo) and maximum force (Fn) are for guidance only, there is no tolerance on the free length (Lo) and force (Fn)
Mean diameter (Dm) tolerances DIN 2095 (Grade 2)
Coil ratio (Dm / d)
Series B is all springs with 11 digits in the item number. E.g. C04800551250M
Series B originally come from an American standard series measured in inches. Inches are converted into mm and the numbers are therefore slightly "skewed".
Series B compression springs are not defined in the same way as series A. In series B the number of coils is not stated, as this series is produced with the force as the determining parameter. The number of coils may therefore vary, and will consequently not be stated.
In series B there is tolerance on the outside diameter (De), end force (Fn) and spring constant (R)