What Is Cold Forging: Cold Forging Process, Advantages and Steps

What is the cold forging process?

The cold forging process, also known as cold extrusion or cold forming, is a technique for precisely extruding and forming metal at room temperature, distinguishing it from hot forging and warm forging. There is no need to preheat the blank materials. Its deformation resistance and forming efficiency are about twice as high as warm forging and four to five times higher than hot forging. This places higher demands on the plasticity and elongation of the raw materials, usually requiring special surface treatments like phosphating or the use of special lubricants.

The cold forging process shapes the material by deforming it, resulting in minimal metal waste during manufacturing. Additionally, because the material is processed at room temperature without heating, the dimensional accuracy is good, and it allows for high-speed processing of around 100 units per minute, even for complex and difficult shapes.

The cold forging process has high material utilization efficiency, enabling high precision and high-speed processing, and is referred to as an "environmentally friendly and rational" processing technology.

Die design is crucial in the cold forging process, employing a three-layered structure to meet specific hardness standards to prevent die damage and ensure excellent product forming results. Although the cold forging process can achieve products with a finer structure, the complexity of shapes is relatively limited.

Advantages of the cold forging process

High material utilization efficiency— The cold forging technology forms the material by deforming it, generally using an amount of material equivalent to the weight of the finished product. This achieves high material utilization efficiency and significantly reduces material costs.

High-speed production— The cold forging technology enables high-speed production of roughly 100 pieces per minute. Since processing occurs at room temperature and does not require heating the metal, dimensional changes are minimal, allowing even complex and difficult shapes to be processed.

Improved mechanical properties— Process designs that consider fiber flow lines can produce parts with excellent strength and wear resistance.

Reduced part costs— When the production conditions, such as required precision and batch size, match, the cold forging technology, which has high material efficiency and enables high-speed processing, can significantly reduce part costs in mass production.

The cold forging process steps

Cold forging is a metal forming process carried out at room temperature, which is significantly lower than the recrystallization temperature of the involved metal. Unlike hot forging, which involves heating the metal to high temperatures, cold forging involves the plastic deformation of metal under ambient conditions. This method usually produces excellent surface finishes, increased strength due to work hardening, and higher dimensional accuracy.

1. Material selection

Select appropriate materials that can withstand the stresses of cold forging, typically metals like steel, aluminum, and copper.

2. Lubrication

Before forging, the workpiece is typically lubricated to reduce friction and wear on the die and to facilitate material flow.

3. Dies and tools

Create custom dies for shaping the workpiece. These dies must be made from materials harder than the workpiece to withstand the pressures of cold forging.

4. Forging process

The metal workpiece is placed between the dies.

A press (usually a mechanical or hydraulic press) applies quick and powerful impacts to the workpiece, causing it to deform and take the shape of the die cavity.

Depending on the complexity of the part, multiple forging operations may be required. This may involve different sets of dies for various stages of pressing.

5. Trimming and finishing

Any excess material, such as flash produced during forging, is trimmed off.

Additional finishing processes, like shot blasting, cleaning, or heat treatment (to relieve stress), may also be applied.