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Hex Flange Bolts are one-piece fastening components designed with an integrated flange under the hexagonal head, eliminating the need for a separate washer and distributing load more evenly across the joint surface. Manufactured according to DIN 6921, ISO 4162, and ASTM standards, these bolts are widely used in automotive assemblies, heavy machinery, structural steel frameworks, and industrial equipment where vibration resistance and load stability are critical.
Made from stainless steel, carbon steel, and alloy steel grades, hex flange bolts provide superior clamping force and enhanced resistance to loosening under dynamic loads. Their flanged head design improves surface contact, reducing stress concentration and increasing joint reliability.
KK Fasteners supplies precision-engineered hex flange bolts to OEMs, EPC contractors, and distributors across global industrial markets, ensuring dimensional accuracy, full material traceability, and consistent mechanical performance for mission-critical applications.
| Parameter | Specification |
|---|---|
| Material Grades | Stainless Steel 304, 304L, 316, 316L, Carbon Steel, Alloy Steel |
| Property Classes / Strength Grades | 4.6, 8.8, 10.9, 12.9 (ISO 898-1) |
| Size Range | M5 to M36 (Metric Series) |
| Thread Type | Metric Coarse, Metric Fine, UNC, UNF |
| Standards | DIN 6921, ISO 4162, ASTM F568, BS 3692 |
| Head Type | Hex Flange Head (Serrated / Non-Serrated) |
| Surface Finish / Coating | Plain, Zinc Plated, Hot Dip Galvanized, Black Oxide, PTFE Coated |
| Hardness | Up to 39–44 HRC (Based on Grade 10.9 / 12.9) |
| Tensile Strength | Up to 1200 MPa (High Tensile Variants) |
| Manufacturing Process | Cold Forging, CNC Threading, Heat Treatment (for high-strength grades) |
| Screw Thread d |
M5 | M6 | M8 | ||
|---|---|---|---|---|---|
| P | Pitch | Coarse thread | 0.8 | 1 | 1.25 |
| Fine thread-1 | / | / | 1 | ||
| Fine thread-2 | / | / | / | ||
| Length of Thread b |
L≤125 | 16 | 18 | 22 | |
| 125＜L≤200 | / | / | 28 | ||
| L＞200 | / | / | / | ||
| c | min | 1 | 1.1 | 1.2 | |
| da | Form A | max | 5.7 | 6.8 | 9.2 |
| Form B | max | 6.2 | 7.4 | 10 | |
| dc | max | 11.8 | 14.2 | 18 | |
| ds | max | 5 | 6 | 8 | |
| min | 4.82 | 5.82 | 7.78 | ||
| du | max | 5.5 | 6.6 | 9 | |
| dw | min | 9.8 | 12.2 | 15.8 | |
| e | min | 8.71 | 10.95 | 14.26 | |
| f | max | 1.4 | 2 | 2 | |
| k | max | 5.4 | 6.6 | 8.1 | |
| k1 | min | 2 | 2.5 | 3.2 | |
| r1 | min | 0.25 | 0.4 | 0.4 | |
| r2 | max | 0.3 | 0.4 | 0.5 | |
| r3 | min | 0.1 | 0.1 | 0.15 | |
| r4 | ≈ | 3 | 3.4 | 4.3 | |
| s | max=nominal size | 8 | 10 | 13 | |
| min | 7.78 | 9.78 | 12.73 | ||
| t | max | 0.15 | 0.2 | 0.25 | |
| min | 0.05 | 0.05 | 0.1 | ||
| Screw Thread d |
M10 | M12 | M14 | ||
|---|---|---|---|---|---|
| P | Pitch | Coarse thread | 1.5 | 1.75 | 2 |
| Fine thread-1 | 1.25 | 1.5 | 1.5 | ||
| Fine thread-2 | 1 | 1.25 | / | ||
| Length of Thread b |
L≤125 | 26 | 30 | 34 | |
| 125＜L≤200 | 32 | 36 | 40 | ||
| L＞200 | / | / | / | ||
| c | min | 1.5 | 1.8 | 2.1 | |
| da | Form A | max | 11.2 | 13.7 | 15.7 |
| Form B | max | 12.6 | 15.2 | 17.7 | |
| dc | max | 22.3 | 26.6 | 30.5 | |
| ds | max | 10 | 12 | 14 | |
| min | 9.78 | 11.73 | 13.73 | ||
| du | max | 11 | 13.5 | 15.5 | |
| dw | min | 19.6 | 23.8 | 27.6 | |
| e | min | 16.5 | 17.62 | 19.86 | |
| f | max | 2 | 3 | 3 | |
| k | max | 9.2 | 11.5 | 12.8 | |
| k1 | min | 3.6 | 4.6 | 5.1 | |
| r1 | min | 0.4 | 0.6 | 0.6 | |
| r2 | max | 0.6 | 0.7 | 0.9 | |
| r3 | min | 0.2 | 0.25 | 0.3 | |
| r4 | ≈ | 4.3 | 6.4 | 6.4 | |
| s | max=nominal size | 15 | 16 | 18 | |
| min | 14.73 | 15.73 | 17.73 | ||
| t | max | 0.3 | 0.35 | 0.45 | |
| min | 0.15 | 0.15 | 0.2 | ||
| Screw Thread d |
M16 | M20 | ||
|---|---|---|---|---|
| P | Pitch | Coarse thread | 2 | 2.5 |
| Fine thread-1 | 1.5 | 1.5 | ||
| Fine thread-2 | / | / | ||
| Length of Thread b |
L≤125 | 38 | 46 | |
| 125＜L≤200 | 44 | 52 | ||
| L＞200 | 57 | 65 | ||
| c | min | 2.4 | 3 | |
| da | Form A | max | 17.7 | 22.4 |
| Form B | max | 20.7 | 25.7 | |
| dc | max | 35 | 43 | |
| ds | max | 16 | 20 | |
| min | 15.73 | 19.67 | ||
| du | max | 17.5 | 22 | |
| dw | min | 31.9 | 39.9 | |
| e | min | 23.15 | 29.87 | |
| f | max | 3 | 4 | |
| k | max | 14.4 | 17.1 | |
| k1 | min | 5.8 | 6.8 | |
| r1 | min | 0.6 | 0.8 | |
| r2 | max | 1 | 1.2 | |
| r3 | min | 0.35 | 0.4 | |
| r4 | ≈ | 6.4 | 8.5 | |
| s | max=nominal size | 21 | 27 | |
| min | 20.67 | 26.67 | ||
| t | max | 0.5 | 0.65 | |
| min | 0.25 | 0.3 | ||
b1 for L ≤ 125 mm
b2 for 125mm < L ≤ 200 mm
b3 for L > 200 mm
|
Nominal |
Width Across Flats (F) |
Width |
Flange |
Body Diameter (E) |
Head Height (H) |
Hex |
Thread |
|||
| Max | Min | Min | Max | Max | Min | Max | Min | Basic | ||
| M5 | 8.00 | 7.78 | 8.71 | 11.80 | 5.00 | 4.82 | 5.40 | 2.80 | 16.00 | |
| M6 | 10.00 | 9.78 | 10.95 | 14.20 | 6.00 | 5.82 | 6.60 | 3.40 | 18.00 | |
| M8 | 13.00 | 12.73 | 14.26 | 18.00 | 8.00 | 7.78 | 8.10 | 4.20 | 22.00 | |
| M10 | 15.00 | 14.73 | 16.50 | 22.30 | 10.00 | 9.78 | 9.20 | 5.70 | 26.00 | |
| M12 | 16.00 | 15.73 | 17.62 | 26.60 | 12.00 | 11.73 | 11.50 | 6.10 | 30.00 | |
| M14 | 18.00 | 17.73 | 19.86 | 30.50 | 14.00 | 13.73 | 12.80 | 7.10 | 34.00 | |
| M16 | 21.00 | 20.67 | 23.15 | 35.00 | 16.00 | 15.73 | 14.40 | 8.70 | 38.00 | |
Hex Flange Bolts are used in assemblies where secure fastening, vibration resistance, and load distribution are essential across mechanical and structural systems.
Hex flange bolts are manufactured using precision cold forging and CNC threading processes to achieve consistent dimensional accuracy and mechanical strength. Heat treatment is applied for higher strength grades such as 10.9 and 12.9 to achieve required hardness levels.
Each batch undergoes strict quality control including dimensional inspection, thread gauge testing, hardness verification, and surface coating validation. Lot traceability ensures every shipment can be tracked back to raw material heat numbers and production batches.
At KK Fasteners, quality assurance protocols align with ISO 9001 standards, ensuring consistent performance across global supply chains and industrial applications where failure is not an option.
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Hex flange bolts are fasteners with an integrated flange beneath the hex head that spreads the load over a wider surface area. This eliminates the need for a separate washer and improves resistance to loosening under vibration. They are widely used in automotive, machinery, and structural steel assemblies where consistent clamping force is required.
Hex flange bolts are manufactured in stainless steel (304, 304L, 316, 316L), carbon steel, and alloy steel grades. Stainless steel is preferred for corrosion resistance in marine and chemical environments, while carbon steel grades like 8.8, 10.9, and 12.9 are used in high-load structural and mechanical applications.
These bolts are commonly produced according to DIN 6921 and ISO 4162 standards. Additional compliance may include ASTM F568 and BS 3692 depending on application requirements. These standards ensure dimensional accuracy, mechanical strength, and global compatibility in industrial assemblies.
Hex flange bolts are used in automotive engine assemblies, heavy machinery, steel structures, railway systems, and industrial equipment. Their vibration resistance and high clamping strength make them suitable for dynamic and load-bearing applications where joint stability is critical.
A reliable manufacturer should offer ISO-certified production, material traceability, compliance with international standards like DIN and ISO, and proper testing facilities for hardness and tensile strength. Companies like KK Fasteners also provide export documentation and consistent quality control for global buyers.
