Cold Forging: Leveraging the plasticity of metals and applying cold state mechanics to exert pressure or cold draw, the objective is to attain solid-state deformation of metal.
This involves creating a method of forging at room temperature to thicken the top of bars or wires, often referred to as cold extrusion.
The primary use of this is for creating components such as bolts, nuts, iron nails, rivets, and steel balls.
Apart from carbon steel, you can choose from metals such as copper, aluminum, alloy steel, stainless steel, and titanium alloys, with a material utilization rate of 80-90%. Through specialized cold forging machines, continuous, multi-position, and automated production can be realized. These machines can sequentially accomplish cutting, forging, accumulation, deformation, chamfering, threading, diameter reduction, and cutting edges. They are highly productive, reaching up to 300 pieces per minute.
Is the hexagonal head of screws cold-forged?
The majority are produced using cold forging since this process saves time and costs. However, small quantities of specialized or unique bolt heads are milled after being turned.
The forming of hexagonal heads of the bolt varies; there are those obtained through cold forging, hot forging, direct output after forging, output after machining post forging, and those entirely machine-forged.
How are threads made?
For single pieces or small batches, methods such as die threading, thread pick off on lathes, and whirlwind milling can be used. However, these techniques are not efficient and can lead to waste.
For large quantities of plain bolts (cold-forged) and raw studs (hot-forged) that require threads, it is necessary to use threading machines which are highly efficient and produce almost no waste. At the Shanghai Fastener Professional Exhibition, you can find top global threading machine manufacturers.
The production of ordinary screws generally involves two steps. First, forming the head through cold forging, warm forging, or hot forging; Secondly, threading is created based on the previous step. Most screws also undergo surface treatment and heat treatment before leaving the factory.
Example: The complete manufacturing process of a Grade 8.8 galvanized hexagon head bolt
Wire Annealing – Acid Washing – Wire Drawing – Forging (Head creation) – Threading – Heat Treatment – Plating – Packaging
Glossary:
Annealing: A step in metal heat treatments for controlling hardness. Usually, a ball annealing furnace is used.
Acid Washing: The process of removing rust and impurities from the wire surface.
Wire Drawing: This involves pulling the wire cold to the diameter required for producing bolts.
Cold Forged Wire: The wire after drawing, acid washing or heat treatment processes is called cold-forged or cold-punched wire.
Forging: Cold forging involves extruding the bolt head. Bolt threads with larger diameters than M24 (or 1 inch) are generally not made using cold extrusion technology.
Threading or Thread Rolling: Creating threads using thread or gear rolling machines.
Heat Treatment: Heating with industrial furnace then insulating and finally cooling to change the crystal structure of the metal, to achieve the performance level required for fastening.
Galvanizing: A surface treatment that often involves galvanizing the surface to prevent corrosion.