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China Suppliers Factory Hot Dipped Galvanized Hdg Din933 Hex Head Bolt
Production Parameter
| Thread size d |
M12 | M16 | M20 | M22 | M24 | M30 | |||
| P | pitch | 1.75 | 2 | 2.5 | 2.5 | 3 | 3.5 | ||
| ds | Max | 12.7 | 16.7 | 20.84 | 22.84 | 24.84 | 30.84 | ||
| Min | 11.3 | 15.3 | 19.16 | 21.16 | 23.16 | 29.16 | |||
| s | Max | 18 | 24 | 30 | 34 | 36 | 46 | ||
| Min | 17.57 | 23.16 | 29.16 | 33 | 35 | 45 | |||
| e | Max | 20.7 | 27.7 | 34.6 | 39.3 | 41.6 | 53.1 | ||
| Min | 19.85 | 26.17 | 32.95 | 37.29 | 39.55 | 50.85 | |||
| dw | Min | 16.5 | 22 | 27.7 | 31.35 | 33.2 | 42.7 | ||
| c | Max | 0.6 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | ||
| Min | 0.15 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | |||
| da | Max | 14.7 | 18.7 | 24.4 | 26.4 | 28.4 | 35.4 | ||
| r | Min | 0.6 | 0.6 | 0.8 | 0.8 | 0.8 | 1 | ||
| k | Max | 7.95 | 10.75 | 13.4 | 14.9 | 15.9 | 19.75 | ||
| Min | 7.05 | 9.25 | 11.6 | 13.1 | 14.1 | 17.65 | |||
| b | Single nut bolt | according to | d + 9 | d + 9 | d + 8 | d + 9 | d + 7 | d + 6 | |
| nominal | 21 | 25 | 28 | 31 | 31 | 36 | |||
| Double nut bolt | according to | 1.8d + 9 | 1.8d + 10 | 1.8d + 10 | 1.8d + 13 | 1.8d + 11 | 1.8d + 8 | ||
| nominal | 30.6 | 38.8 | 46 | 52.6 | 54.2 | 62 | |||
Production Description
HDG generally refers to hot-dip galvanizing. Hot-dip galvanizing is to make the molten metal react with the iron matrix to produce an alloy layer, so that the matrix and the coating are combined. Hot-dip galvanizing is to pickle the iron and steel parts first, in order to remove the iron oxide on the surface of the iron and steel parts, after pickling, it is cleaned in a tank of ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to the hot dip coating tank. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life.
The countersunk head of hot dip galvanized bolts is usually used where the connection is required. It is a non-standard part in the shape of a U and is therefore also known as a U-bolt. Hot-dip galvanized bolts with threads at both ends can be used in combination with nuts. The utility model is mainly used for fixing tubular or flaky objects.
The corrosion resistance is mainly determined by the thickness of the galvanized layer, so the thickness measurement is often the main basis for judging the quality of the galvanized layer. The angle and speed of the solution also have a great influence. Therefore, it is practically impossible to obtain a completely uniform coating thickness.
Frequently Asked Questions (FAQ)
1. What is HDG (Hot-Dip Galvanizing) and how does it protect bolts?
Hot-dip galvanizing is a process where steel or iron parts are pickled and dipped into molten zinc to create a metallurgical reaction. This forms a protective zinc-iron alloy layer that guards the base metal against corrosion, providing strong adhesion and a long service life.
2. Why are pickling and cleaning processes critical before hot-dip galvanizing?
Pickling is essential to remove iron oxides and rust from the surface of the steel parts. Following pickling, cleaning the parts in an aqueous solution of ammonium chloride, zinc chloride, or a mixed solution ensures a clean surface, enabling a uniform and strong adhesion of the zinc coating.
3. How is the quality of the galvanized layer measured?
The quality and corrosion resistance of the galvanized layer are primarily determined by its thickness. Measuring this thickness serves as the main basis for quality assessment.
4. Why is it difficult to achieve a completely uniform coating thickness on HDG bolts?
A completely uniform coating thickness is practically impossible to achieve because the final thickness is heavily influenced by external factors during production, such as the angle and withdrawal speed of the solution.
5. What are the common applications for hot-dip galvanized bolts?
These bolts, including non-standard designs like U-bolts, are commonly used in combination with nuts for secure connections. They are primarily utilized to fix tubular or flat objects in environments requiring high corrosion resistance.