Disc Springs (Belleville Washers)
Material, manufacturing, hardness, tolerances and allowable stress — the conditions every certified disc spring must satisfy.
Spring grade steels 50CrV, 51CrMnV and 60Si2Mn per GB/T 1222-2025. Strip per GB/T 3279 / YB/T 5058; forged stock (forging ratio ≥ 2) per GB/T 1222. Every heat comes with a mill certificate and is re-checked before use.
| Group | Thickness t | Typical process chain |
|---|---|---|
| 1 | 0.20 – 1.25 mm | Blanking → cold/hot forming → edge rounding (fine-blanked edges: b₁/t ≤ 15 %, polished band hs/t ≥ 75 %) |
| 2 | 1.25 – 6.00 mm | Blanking → forming → machining of D/d → edge rounding → heat treatment; or machining of supporting surfaces after heat treatment |
| 3 | 6.00 – 14.00 mm | Hot forming → full machining → edge rounding, or blanking → machining → heat treatment |
Group 1: 425–510 HV10. Groups 2 and 3: 42–52 HRC. Special hardness windows by agreement.
After quench and temper, total decarburized depth per side ≤ 3 % of thickness (max 0.15 mm). For t ≤ 0.3 mm, ≤ 0.01 mm. Hardened no more than twice.
After heat treatment, springs are pressed at least twice the test load Fₛ to flat, producing controlled permanent set that stabilizes load and improves relaxation behaviour.
Phosphating or equivalent; electroplating is discouraged (hydrogen embrittlement). Shot peening per GB/T 31214.1 when specified for fatigue duty.
Static duty: computed stress at OM position when fully flat, σOM ≤ 1 600 MPa (above that, σ₁ ≤ 3 000 MPa per GB/T 1972.1). Dynamic duty: minimum pre-deflection s ≈ 0.15–0.20 h₀ avoids position-I cracking; life is verified against the 10⁵ / 5×10⁵ / 2×10⁶ cycle diagrams.
Thickness, D/d (class I or II), free height and test-load tolerances per Tables 5–8 of the standard; e.g. thickness tolerance ± 0.03/− 0.06 mm (group 1, t ≤ 0.6) down to ± 0.15 mm (group 3). Concentricity 2×IT11 (class I) or 2×IT13 (class II).
Source standard: GB/T 1972.2-2023 Belleville springs — Part 2: Technical requirements (data transcribed from Annex B). Material steel per GB/T 1222.
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