Rivet Nut

Cold Forming in Hex Bolt Manufacturing

Renowned hex bolt manufacturers often utilize a technique known as cold forming. This method involves a series of dies in a machine, shaping a metal blank into the hex bolt’s final dimensions without heating. Large steel wire rods are first straightened and cut to size. The metal, kept at room temperature, is then precisely shaped using these dies under substantial pressure.

After the initial shaping, thread rolling is applied to the hex bolt’s shaft. The bolt then undergoes heat treatment to enhance tensile strength and hardness. To protect against corrosion, a final step often includes zinc coating or hot-dipping. Despite the complexity and precision required in this process, cold forging allows for rapid, large-scale, and consistent production of hex bolts.

Work Hardening in Cold Forming

During cold forming, hex bolts undergo work hardening, enhancing their strength due to the unaltered grain structure of the steel, which is reoriented rather than cut or heated. However, the ability to produce varying sizes of bolts is somewhat limited in cold forming, as larger diameters require more force.

Hot Forging for Larger Bolts

When hex bolts are too large for cold forging or require more pliability, hot forging is employed. This involves heating the steel until it becomes malleable and then shaping it in a die. Hot forging is particularly effective for producing large-diameter bolts, as the heated steel is much more ductile, allowing for more diverse shapes and designs.

Machining Steel Hex Bolts

Machining involves removing and cutting steel to achieve specific bolt specifications. This method has no size or shape limitations, making it ideal for producing complex bolt designs. However, the downside is the material waste generated, and since the grain flow is disrupted, the bolt doesn’t undergo work hardening, potentially reducing its strength.

Types and Grades of Hex Bolts

Hex bolts are categorized based on their strength properties and material composition. In the U.S., common grades are 2, 5, and 8, with each grade indicating increased hardness and tensile strength. Outside the U.S., metric grading is used.

Grade 8 Hex Bolts: Made from carbon-steel alloy, these bolts are used in demanding applications like the military and aerospace, due to their high tensile strength.

Grade 2 Hex Bolts: Constructed from lower-strength carbon steel, these bolts are more cost-effective and suitable for less critical applications.

Selecting the Right Hex Bolt Manufacturer

To ensure optimal results when purchasing hex bolts, it’s crucial to compare multiple manufacturers. Each hex bolt supplier will have different areas of expertise and capabilities. By reviewing their business profiles and contacting them directly, you can gain insights into what each company specializes in. Using a simple RFQ form, you can reach out to multiple businesses simultaneously, making the selection process more efficient.