How to Make Steel Bolts - Hot Forging
2025/9/8 view:
Hot forging is a process by which steel is heated to make it malleable and formed in a die. This process increases the material's ductility, making it even easier to shape. It does come with some compromises as regards energy use and final material properties, though, versus cold forging operations.
Size & Shape
When heated above the recrystallization temperature of steel, it becomes highly ductile, and more bolts can be produced with less pressure. Large-diameter bolt production has a plus point in hot forging, which is usually difficult by cold forming. The range of size also expands with higher ductility, and hot forging is a suitable option for special bolt shapes which cannot be produced by cold forming.
Waste
As in cold forging, no material is wasted in hot forging through the removal of material in the form of chips. However, the process requires more energy in heating the steel, possibly at additional expense to offset partially the savings in material waste. Material waste overall is minimal, but energy use must be taken into account.
Strength
Hot forging reduces the occurrence of work hardening. Although it retains some grain structure, the heat involved in the process changes the grains sufficient enough to reduce the strengthening effect that may be caused by cold forming. The hot forged bolts are therefore strong, but may not gain the same degree of strengthening as the bolts designed using the hot forging process of cold forming.
Material
Most often, the characteristics of the material rule out the choice of the production process. In general, hot forging is used where a material is poorly cold formable or poorly machinable. Some materials must be hotter in order to properly shape the material, and hot forging is used as a last resort when a better one is not available.
Size & Shape
When heated above the recrystallization temperature of steel, it becomes highly ductile, and more bolts can be produced with less pressure. Large-diameter bolt production has a plus point in hot forging, which is usually difficult by cold forming. The range of size also expands with higher ductility, and hot forging is a suitable option for special bolt shapes which cannot be produced by cold forming.
Waste
As in cold forging, no material is wasted in hot forging through the removal of material in the form of chips. However, the process requires more energy in heating the steel, possibly at additional expense to offset partially the savings in material waste. Material waste overall is minimal, but energy use must be taken into account.
Strength
Hot forging reduces the occurrence of work hardening. Although it retains some grain structure, the heat involved in the process changes the grains sufficient enough to reduce the strengthening effect that may be caused by cold forming. The hot forged bolts are therefore strong, but may not gain the same degree of strengthening as the bolts designed using the hot forging process of cold forming.
Material
Most often, the characteristics of the material rule out the choice of the production process. In general, hot forging is used where a material is poorly cold formable or poorly machinable. Some materials must be hotter in order to properly shape the material, and hot forging is used as a last resort when a better one is not available.
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