Disc Springs

Disc springs are conical spring elements made of hardened spring steel that generate a high axial restoring force through elastic deformation. They compensate for settlement, relaxation, and thermal linear expansion in bolted joints and are used under dynamic or thermal loads. They are not suitable for electrically conductive connections or as anti-rotation devices. Advantages include high preload, lifetime, and an adjustable spring characteristic curve; disadvantages include, among other things, the reduced compression cone, susceptibility to corrosion, and high design complexity. They comply with standards such as DIN EN 16983 and VDI 2230. For multifunctional requirements, NSK washers are a superior alternative.

  1. Design and Function
    Disc springs are conical, ring-shaped spring elements made of hardened spring steel (e.g., DIN EN 10132-4) that are axially compressed when the screw is tightened. This creates a defined, elastic preload.
    Typically, there are two contact zones:
    1. inside, beneath the screw head or nut
    2. externally on the contact area.
  2. Principles of Operation
    When tightened, the disc spring stores elastic energy and generates a high restoring force that:
    1. compensates for settling,
    2. relaxation, and
    3. thermal linear expansion.
    By stacking multiple springs, the characteristic curve can be specifically adjusted (soft/hard).
  3. Application
    Disc springs are used where high preload forces must be maintained over the long term—e.g., in:
    1. Press-fit connections, turbines, pipe flanges
    2. dynamic loads or temperature changes

    Not suitable for:
    1. preventing self-acting loosening by rotation
    2. soft contact areas
    3. Electrical contact glands according to DIN EN 17976
    4. Electrically conductive connections with insulating layers
  4. Advantages
    1. Very high axial spring force
    2. Compensation for settlement loss and relaxation
    3. Adjustable characteristic curve through parallel connection
    4. High reliability under dynamic loads
    5. Long lifetime when correctly designed
    6. Compensation for short-term overloading
  5. Disadvantages
    1. No protection against loosening under transverse loads
    2. Reduced compression cone; risk of local plastic deformation
    3. Complex design, especially for stacked applications
    4. Susceptible to corrosion if unprotected
    5. Sensitive to eccentricity
    6. Higher costs than standard washers
  6. Normative Classification
    Disc springs are subject to the following standards, among others:
    1. DIN EN 16983 (formerly DIN 2093) – Dimensions and technical requirements
    2. DIN EN ISO 4042 – Corrosion protection
    3. VDI 2230 – Design of high-load bolted joints

    These define tolerances, materials, hardness ranges, and test methods.
  7. Design Guidelines
    1. Use only on hard, flat, clean surfaces
    2. Install concentrically; avoid eccentricity
    3. Ensure corrosion protection (e.g., phosphating)
    4. Check residual height after settlement test (DIN EN 16983)
    5. Calculate spring characteristic curve, especially for spring assemblies
    6. Not a standalone solution for lateral loads → combine with anti-rotation devices if necessary
  8. Recommendation
    Disc springs are purely mechanically effective elements for preventing loosening. For applications with combined requirements (e.g., against loosening, slippage, and sliding), multifunctional NSK washers in the NSK-L (steel) and NSK-N (stainless steel) variants are a technically superior alternative.

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