DIN 6796 - Belleville Heavy Load Washers
The Belleville Load Washer is used to apply a reliable and steady Preload to Static Bolted Connections.
Static Bolted Connections
Called a variety of names Belleville/Bevel, Cup, Heavy Load and High Torque Washers, regardless of the name used the function is the same, and this is to ensure a permanent pressure to the union between a bolt and a nut to prevent the loss of pre-load on it; This static fix remains regardless of vibrations or heat change dynamics which may appear over time. They are used to secure bolted connections with high load demands.
Fig 1 - How the DIN6796 ensures a constant preload on a bolted connection
The key points to note are:
- Typically used with hardened bolts ranging from grade 8.8, 10.9 and 12.9 (US-Grade 5, 8 & A325)
- They are made from spring steel alloys - we mostly use SAE1065 and SAE6150 (for thicker cross sections)
- They are through hardened to between Vickers HV 420 and 510 (Rockwell C, HRC 43-52)
- We use a high temperature oxidizing process as the surface treatment on the high carbon content versions.
- We prefer to avoid electroplating, as this requires an additional de-embrittlement step, which is unreliable in smaller cross-sections
- In flux dense environments we use various stainless steels including INCONEL-x750 to avoid induction heating and issues with a degradation of the Young's Modulus of Elasticity
Dimensions - DIN 6796.
Fig 2 - DIN6796 Dimension Schematic / Reference
Legend:
d1 - Inner diameter
d2 - Outer diameter
S - Material Thickness
h - Overall Unloaded Washer Height
| Bolt Size | ID (mm) | OD (mm) | S (mm) | hmax (mm) | hmin (mm) | kg of 1000 pieces |
|---|---|---|---|---|---|---|
| M2 | 2.2 | 5 | 0.4 | 0.6 | 0.5 | 0.05 |
| M2.5 | 2.7 | 6 | 0.5 | 0.72 | 0.61 | 0.09 |
| M3 | 3.2 | 7 | 0.6 | 0.85 | 0.72 | 0.14 |
| M3.5 | 3.7 | 8 | 0.8 | 1.06 | 0.92 | 0.25 |
| M4 | 4.3 | 9 | 1 | 1.3 | 1.12 | 0.38 |
| M5 | 5.3 | 11 | 1.2 | 1.55 | 1.35 | 0.69 |
| M6 | 6.4 | 14 | 1.5 | 2 | 1.7 | 1.43 |
| M7 | 7.4 | 17 | 1.75 | 2.3 | 2 | 2.53 |
| M8 | 8.4 | 18 | 2 | 2.6 | 2.4 | 3.13 |
| M10 | 10.5 | 23 | 2.5 | 3.2 | 2.8 | 6.45 |
| M12 | 13 | 29 | 3 | 3.95 | 3.43 | 12.4 |
| M14 | 15 | 35 | 3.5 | 4.65 | 4.04 | 21.6 |
| M16 | 17 | 39 | 4 | 5.25 | 4.58 | 30.4 |
| M18 | 19 | 42 | 4.5 | 5.6 | 5.08 | 38.9 |
| M20 | 21 | 45 | 5 | 6.4 | 5.6 | 48.8 |
| M22 | 23 | 49 | 5.5 | 7.05 | 6.15 | 63.5 |
| M24 | 25 | 56 | 6 | 7.75 | 6.77 | 92.9 |
| M27 | 28 | 60 | 6.5 | 8.35 | 7.3 | 113 |
| M30 | 31 | 70 | 7 | 9,2 | 8 | 170 |
| M33 | 34 | 76 | 7.5 | 10 | 8.5 | 214 |
| M36 | 38 | 83 | 8 | 10.5 | 9 | 271 |
| M42 | 44 | 96 | 8.5 | 12 | 10.5 | 383 |
| M48 | 49.5 | 110 | 9 | 12.5 | 11 | 535 |
| M56 | 58 | 128 | 9.5 | 13.5 | 12 | 763 |
| M64 | 66 | 136 | 10 | 14 | 12.5 | 870 |
| M72 | 74 | 145 | 10.5 | 15 | 13 | 1006 |
| M90 | 93 | 160 | 11 | 16 | 14 | 1155 |
| M100 | 103 | 180 | 11.5 | 17 | 15 | 1552 |
| M125 | 128 | 220 | 12 | 19 | 16.5 | 2368 |