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JIS B 1256 (NA):2008 Grade A Flat Washer
JIS B 1256 (NA):2008 Grade A Flat Washer is used in standard bolt-and-nut connections within the JIS system. Grade A dimensional accuracy helps maintain consistency in inner diameter, outer diameter, and thickness, creating a stable contact surface during assembly.
This washer is suitable for machinery, precision assemblies, Japanese-standard supply, and maintenance spare parts. Its main functions are to distribute pressure, protect the workpiece surface, and improve contact conditions between the nut or bolt head and the connected part.
Different materials and finishes, such as zinc plating, black oxide, or stainless steel, can be selected according to project requirements for corrosion protection, appearance, and assembly reliability.
Dimensions unit: mm
| Nominal diameter d | Φ1.6 | Φ2 | Φ2.5 | Φ3 | (Φ3.5) | Φ4 | Φ5 | Φ6 | Φ8 | Φ10 | Φ12 | (Φ14) | Φ16 | (Φ18) | Φ20 | |
| d | Min. | 1.7 | 2.2 | 2.7 | 3.2 | 3.7 | 4.3 | 5.3 | 6.4 | 8.4 | 10.5 | 13 | 15 | 17 | 19 | 21 |
| Max. | 1.84 | 2.34 | 2.84 | 3.38 | 3.88 | 4.48 | 5.48 | 6.62 | 8.62 | 10.77 | 13.27 | 15.27 | 17.27 | 19.33 | 21.33 | |
| dc | Max. | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 12 | 16 | 20 | 24 | 28 | 30 | 34 | 37 |
| Min. | 3.7 | 4.7 | 5.7 | 6.64 | 7.64 | 8.64 | 9.64 | 11.57 | 15.57 | 19.48 | 23.48 | 27.48 | 29.48 | 33.38 | 36.38 | |
| h | Nominal | 0.3 | 0.3 | 0.5 | 0.5 | 0.5 | 0.8 | 1 | 1.6 | 1.6 | 2 | 2.5 | 2.5 | 3 | 3 | 3 |
| Max. | 0.35 | 0.35 | 0.55 | 0.55 | 0.55 | 0.9 | 1.1 | 1.8 | 1.8 | 2.2 | 2.7 | 2.7 | 3.3 | 3.3 | 3.3 | |
| Min. | 0.25 | 0.25 | 0.45 | 0.45 | 0.45 | 0.7 | 0.9 | 1.4 | 1.4 | 1.8 | 2.3 | 2.3 | 2.7 | 2.7 | 2.7 | |
| Nominal diameter d | (Φ22) | Φ24 | (Φ27) | Φ30 | (Φ33) | Φ36 | (Φ39) | Φ42 | (Φ45) | Φ48 | (Φ52) | Φ56 | (Φ60) | Φ64 | |
| d | Min. | 23 | 25 | 28 | 31 | 34 | 37 | 42 | 45 | 48 | 52 | 56 | 62 | 66 | 70 |
| Max. | 23.33 | 25.33 | 28.33 | 31.39 | 34.62 | 37.62 | 42.62 | 45.62 | 48.62 | 52.74 | 56.74 | 62.74 | 66.74 | 70.74 | |
| dc | Max. | 39 | 44 | 50 | 56 | 60 | 66 | 72 | 78 | 85 | 92 | 98 | 105 | 110 | 115 |
| Min. | 38.38 | 43.38 | 49.38 | 55.26 | 58.8 | 64.8 | 70.8 | 76.8 | 83.6 | 90.6 | 96.6 | 103.6 | 108.6 | 113.6 | |
| h | Nominal | 3 | 4 | 4 | 4 | 5 | 5 | 6 | 8 | 8 | 8 | 8 | 10 | 10 | 10 |
| Max. | 3.3 | 4.3 | 4.3 | 4.3 | 5.6 | 5.6 | 6.6 | 9 | 9 | 9 | 9 | 11 | 11 | 11 | |
| Min. | 2.7 | 3.7 | 3.7 | 3.7 | 4.4 | 4.4 | 5.4 | 7 | 7 | 7 | 7 | 9 | 9 | 9 | |
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Hangzhou Better Fastener Technology Limited
Better Fastener is a professional fastener enterprise specializing in the manufacturing of steel washers, stainless steel washers, spring washers and sealingwashers. Founded in 2001 as a washer factory, the company expanded into a comprehensive enterprise integrating washers, nuts, bolts, spring nuts and other fastener products in 2010.
The company positions itself as a provider of comprehensive one-stop services for customers, relying on technological R&D, industrial investment and trade distribution.
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