We often find that the current standards available for tolerancing springs such as EN13906 and DIN 2076 are ill suited to the demands of our customers.
These standards have over the years gradually increased tolerances allowing springmakers to reduce the standard of work supplied to you the customer. The main reason behind these increases is the manufacturing method, all of the springs we produce are mandrel coiled, which while highly skilled allows for much greater precision than most automatic spring coilers. This has the added benefit of not damaging the surface of the material reducing failure and improving fatigue performance.
Because of the problems with the standards currently available we recommend the following:
Standard load tolerances of ± 5% for both load positions (in some cases this can be reduced to as little as ±1%)
Squareness & Bow tolerances (intended to keep non axial forces to a minimum) of 1/2°
Diameter Tolerances of ±.010″ (standard) or ±.005″ (any parts specified with diameter tolerances of ≤±.005″ require hardened plug gauges for 100% inspection)
Note: We do not normally recommend tolerancing free length, however ±.005″ can be easily achieved
