What is Hot Forging?

Hot forging is a process where metal is heated to a high temperature until it becomes soft, then placed into a precision mold and shaped by applying pressure. During forging, the metal’s internal grain structure is improved, which increases its density, strength, and mechanical properties. This method is widely used in the automotive industry- for example, in chassis parts, drivetrain components, shafts, and high-pressure valve parts. It is also one of the commonly used processes in GHS’s long-term collaborations with vehicle manufacturers.

The Difference between Hot and Cold Forging

Hot：The metal is heated to a temperature above its recrystallization point, typically more than 60% of its melting temperature. At this high temperature, the metal becomes softer and much more ductile, allowing it to flow easily under pressure and fill complex mold shapes.
Cold：Cold forging is performed at room temperature or near room temperature. The metal undergoes strain hardening, which increases the part’s strength and surface hardness. However, formability is reduced, making it more suitable for simpler shapes.

Hot Forging Process

• Heating： The metal material (such as steel bars or aluminum billets) is heated to the forging temperature—for steel, typically around 1000°C to 1250°C.
• Forging： The heated metal is placed into a mold, where forging equipment applies pressure to force the material into the die cavity and form the desired shape.
• Trimming： Excess material, known as flash, formed during forging, is removed.
• Heat Treatment： Processes such as normalizing, quenching, and tempering are performed to relieve stress, refine the grain structure, and enhance mechanical properties.
• Post-processing： Additional finishing steps such as surface treatment (e.g., sandblasting, plating) or precision machining (e.g., CNC machining) are carried out to meet final specifications.

Advantages of Hot Forging

• Enhanced Strength： The metal’s grain structure aligns along the deformation direction, creating a dense fiber-like structure that eliminates defects and significantly improves fatigue strength and toughness.
• Excellent Formability： At high temperatures, the metal flows easily, allowing it to fill complex mold shapes with ease.
• Material and Cost Efficiency： Near-net-shape forged parts reduce machining allowance, minimizing material waste and lowering processing costs.

Applications of Hot Forging

• Automotive： Crankshafts, connecting rods, gears, drive shafts, wheel hubs, steering knuckles.
• Aerospace： Turbine discs, landing gear components, structural brackets.
• Energy： Valves, flanges, pipe fittings.
• Heavy Machinery： Agricultural, construction