Behind the Vital Mechanical Components: The Art of Forging
In the realm of high-load and demanding working conditions for mechanical parts, beyond simple shapes, profiles, or welded components that can be rolled, forged pieces are predominantly utilized.
Forging, an age-old process, involves applying pressure to metal blanks using forging machinery, thereby inducing plastic deformation to yield components with specific mechanical properties, shapes, and dimensions. This method not only eradicates porosity and loose structures in metals and welds but also typically yields components with superior mechanical performance compared to castings made from the same material.
Forging techniques can be categorized based on temperature and the type of production tool employed.
By Temperature:
· Hot Forging: Conducted above approximately 800°C (though the theoretical start of re-crystallization for steel is around 727°C), this is the most common method across industries.
· Warm Forging (or Semi-Hot Forging): Undertaken within the range of 300°C to 800°C, it's primarily used in automotive and general machinery parts, promoting material efficiency.
· Cold Forging: Performed at room temperature, it serves specialized applications.
By Production Tool:
· Free Forging: Utilizes generic tools to shape blanks directly between the anvils of forging equipment. Basic operations include upsetting, drawing out, piercing, cutting, bending, twisting, shifting, and forging joints. Suited for small batches and diverse shapes, executed primarily via hot forging.
· Die Forging: Involves compressing blanks within a shaped die cavity to create precise components. It's ideal for lighter, mass-produced parts and represents the progressive direction of the industry with warm and cold forging technologies.
· Ring Rolling (or Ring Forging): A specialized process using ring rolling machines to produce circular parts, such as wheel rims and train wheels.
· Special Forging: Encompasses methods like roll forging, cross wedge rolling, radial forging, and liquid die forging, tailored for unique part geometries.
Additionally, based on the motion of the forging dies, processes can further be classified into radial forging, swaging, roll forging, cross wedge rolling, ring rolling, and skew rolling.
In sectors like mechanical engineering, crucial components including turbine generator shafts, rotors, impellers, blades, retaining rings, large hydraulic press columns, high-pressure cylinders, rolling mill rollers, engine crankshafts, connecting rods, gears, bearings, and military hardware like artillery, are all fabricated through forging processes.
The reach of forging extends across industries such as metallurgy, mining, automotive, agriculture, petrochemicals, aviation, aerospace, defense, and even into everyday life applications.
The annual output of forgings, the proportion of die forgings in total forging production, and the scale and availability of forging equipment serve as indicative metrics reflecting a nation's industrial prowess. Thus, forging stands as a cornerstone of modern manufacturing, embodying strength, precision, and the advancement of technology in producing some of the world's most critical mechanical components.