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China Suppliers Factory: Galvanized & Blackened Double-Headed Bolts, Grade 4.8 and 8.8, Anti-Loosening Design
| Thread size d | M6 | M8 | M10 | M12 | M14 | M16 | M18 | M20 | M22 | M24 | M27 | M30 | M33 | |
| designation① | D | D | D | D | D | D | D | D | D | D | D | D | D | |
| / | / | D-HDZ | D-HDZ | D-HDZ | D-HDZ | D-HDZ | D-HDZ | D-HDZ | D-HDZ | D-HDZ | D-HDZ | D-HDZ | ||
| ds | Max | 5.32 | 7.16 | 8.99 | 10.83 | 12.66 | 14.66 | 16.33 | 18.33 | 20.33 | 22 | 25 | 27.67 | 30.67 |
| Min | 5.14 | 6.97 | 8.78 | 10.59 | 12.41 | 14.41 | 16.07 | 18.07 | 20.07 | 21.69 | 24.69 | 27.34 | 30.34 | |
| S | Public | 50 | 63 | 75 | 100 | 115 | 125 | 140 | 150 | 165 | 175 | 200 | 200 | 225 |
| Max | 75 | 88 | 100 | 125 | 140 | 150 | 165 | 175 | 190 | 200 | 225 | 225 | 250 | |
| Min | 42 | 55 | 67 | 92 | 107 | 117 | 132 | 142 | 157 | 167 | 192 | 192 | 217 | |
| Connecting nut | M6 | M8 | M10 | M12 | M14 | M16 | M18 | M20 | M22 | M24 | M27 | M30 | M33 | |
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The Function of Double Headed Bolts
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1. Connecting Mechanical Components Double headed bolts have threads at both ends and a screw in the middle, commonly used to connect mechanical components such as mining machinery, bridges, automobiles, motorcycles, boiler steel structures, suspension towers, large-span steel structures, and large buildings.
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2. Installation Accessories When large equipment requires the installation of accessories, such as observation mirrors, mechanical seal seats, reduction frames, etc., double headed bolts can play a role. One end is screwed into the main body, and after installing the accessories, the other end is equipped with a nut. Due to the fact that these attachments may require frequent disassembly, using double headed bolts for replacement would be very convenient.
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3. Connecting Thick Plates & Inconvenient Areas In cases where the thickness of the connectors is large or the connection area is not convenient to use hexagonal bolts, such as concrete roof trusses, roof beam suspensions, monorail beam suspensions, etc., double headed bolts are also a suitable choice.
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4. Fixed Connecting Rod Double headed bolts are also commonly used for mechanical fixed connecting rods, with corresponding threads at both ends. The thickness of the middle screw varies depending on actual usage.
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Frequently Asked Questions (FAQ)
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What is a double headed bolt and how does it differ from a standard bolt?
A double headed bolt (also called a stud bolt) features threads at both ends with a plain or threaded shank in the middle. Unlike a standard bolt which has a head on one end, a double headed bolt is designed to be screwed into a tapped hole on one side and secured with a nut on the other, making it ideal for applications requiring frequent assembly and disassembly.
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What thread sizes are available for double headed bolts?
Double headed bolts are available in a wide range of metric thread sizes, including M6, M8, M10, M12, M14, M16, M18, M20, M22, M24, M27, M30, and M33, to accommodate various industrial and structural applications.
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What does the designation "D-HDZ" mean in the specifications table?
The designation "D-HDZ" refers to a specific surface treatment or product classification for double headed bolts, typically indicating hot-dip galvanized (HDZ) coating, which provides enhanced corrosion resistance. This designation is available for thread sizes M10 and above.
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In what industries are double headed bolts most commonly used?
Double headed bolts are widely used across many industries, including construction (bridges, large buildings, roof trusses), heavy machinery (mining equipment, boiler steel structures), transportation (automobiles, motorcycles), and infrastructure (suspension towers, monorail beam suspensions, large-span steel structures).
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Why are double headed bolts preferred over hexagonal bolts in certain applications?
Double headed bolts are preferred when connectors are too thick for standard hexagonal bolts, or when the connection area does not provide enough clearance for a bolt head. They are also the better choice when components need to be frequently removed and reinstalled, as they protect the threaded hole in the base material from wear.
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How do I select the correct double headed bolt size for my application?
Selecting the correct size involves considering the thread diameter (d), the shank diameter (ds), and the grip length (S) based on the thickness of the materials being joined. Refer to the specifications table above for maximum and minimum values of ds and S for each thread size. Always match the connecting nut thread size to the bolt thread size for a secure fit.