What Is Cold Forming? Definition, Process, and Comparison with Other Manufacturing Processes

Many high-volume industrial components begin their life through a process known as cold forming. Whether it is the general fasteners, electronic parts, or the intricate gears and valves for automotive industry, this cold forming plays a vital role in producing high-strength parts with good utilization of metal material. This article will introduce the cold forming processes, suitable cold forming metal materials, its difference from sheet metal fabrication and hot forging, and why you may need CNC machining for secondary refining your cold form parts.

 

 

 

 

 

What is Cold Forming?

 

 

Cold forming is a high-speed metalworking process where metal is shaped at or near room temperature; That is, metal cold forming utilizes massive hydraulic or mechanical pressure to force the metal into a specific shape(General Cold Forming Process). This cold deformation makes the metal’s crystalline structure is rearranged, and achieved advantages that:

 

• Cost-Effectiveness: It is achieved by high speed automation, which is suitable for large batch.
  
• Improved Properties: The wear resistance and strength were improved by cold working hardening.
  
• Surface Quality: The metal achieves excellent surface finish, typically no need for additional grinding.
  
• Consistency: it can achieve high dimensional repeatability.

 

 

 

 

 

Achieved Ways of Cold Forming Processes 

 

 

Cold forming metal into parts is a general term to call this manufacturing method. But actually, the cold forming includes many detailed processing ways. You can find these processing ways in below table:

 

 

Table 1: Processing Ways of Cold Forming

 

 

 

 

The main difference between the top three processes (Heading, Extrusion, Rolling) and the bottom three (Bending, Stamping, Spinning) is the degree of material displacement:

 

• Bulk Forming (Heading/Extrusion/Rolling): These processes fundamentally change the thickness and volume distribution of the metal. This is where the most significant work hardening occurs.
  
• Sheet Metal Forming (Bending/Stamping): These primarily change the geometry of a flat surface without significantly changing the thickness of the metal.
  

 

 

 

Is Sheet Metal Fabrication the Same as Cold Forming？

 

Although sheet metal forming (bending/stamping) belongs to sheet metal fabrication, sheet metal fabrication and cold forming are different. Besides bending/stamping, sheet metal fabrication uniquely refers to work on flat, thin metal sheets and this can also include laser cutting, punching, welding, and surface finishing (like powder coating) the metal sheets( You start with a 2D plane of a fixed thickness). But for cold forming, it focuses on using high pressure to force metal (usually wire or bars) to flow into a new 3D shape.

 

 

 

 

 

 

Cold Forming vs. Cold Forging: What's the Difference?

 

 

The concepts of "cold forming" and "cold forging" are often used interchangeably. While both processes involve the cold working of steel and other alloys without the application of heat, they differ primarily in the complexity of the part and the nature of the metal flow.

 

Cold forming is a broad "umbrella" term that encompasses various operations such as heading, bending, and extruding. It is most commonly associated with the production of long, symmetrical parts like cold formed fasteners, bolts, and rivets. On the other hand, the cold forging process typically refers to more intense, three-dimensional deformation. Cold forging operations are used to create complex, heavy-duty components—such as gears, pistons, and hollow cylinders—where the metal must undergo significant volumetric changes.

 

While cold forged parts are generally more complex in geometry, both methods share the same primary benefit: strain hardening. Because the metal is deformed while cold, the internal grain structure follows the contour of the part, resulting in a finished product that is significantly stronger than a part machined entirely from a standard bar. Whether you require the high-speed output of a cold heading process or the structural density of cold forging, both techniques provide a robust foundation that can be further perfected through secondary CNC machining.

 

 

 

 

What Metals Are Suitable for Cold Forming?

 

 

Cold forming relies on a metal's ductility—its ability to plastically deform without breaking or cracking at room temperature. Metals with a Face-Centered Cubic (FCC) crystal structure, such as copper and aluminum(1000-6000series), are generally the most suitable because their atoms can shift positions more easily. Carbon steel, stainless steel, and brass can also be cold formed into parts. But their cold forming easy or difficult mainly depends on their different grades. Below table shows the metals that can be cold formed and common cold formed parts examples:

 

 

Table 2: Suitable Metals for Cold Forming 

 

 

 

 

 

 

 

 

 

Cold Forming Parts with Secondary CNC Machining

 

 

Unlike cord forming achieved parts manufacturing through massive hydraulic or mechanical pressure to force the metal into a specific shape; CNC Machining is cutting, drilling, or milling a whole piece of material into the needed shapes, and this process controlled by computer programs to achieve much high precision of the parts(±0.01mm tolerance). Cold forming parts(±0.1mm tolerance) indeed save the material and cost compared to CNC Machining, but if there are more tight tolerance requirements, you may choose CNC Machining for secondary machining. 

 

 

 

Key Advantages of Secondary CNC Processing:

 

• Significant Cost Reduction: Because the cold-formed blank is already near its final shape, the CNC cycle time is greatly reduced. This allows you to achieve more competitive pricing for high-precision parts that would be too expensive to machine entirely from scratch.
  
• Achieving Complex Functionality: Cold forming tooling is limited by the "pull" direction of the die. It cannot create cross-holes, side slots, or intricate internal grooves. Secondary CNC processing machines these cold-formed "blanks" and add those complex details with high precision.
  
• High Hardness Parts Achieved through this way: Thet cold deformation leaves the metal in a "work-hardened" state. This makes the material significantly tougher and more abrasive than standard annealed bars (which is used for CNC machining). 
  

 

By integrating CNC machining with your cold-formed components, you get the best of both aspects: a part that is structurally superior with precision met, and produced at a lower cost.

 

 

 

 

Conclusion

 

 

In summary, cold forming is a high-efficiency manufacturing process that deforms metal at room temperature to create high-strength, high-volume components. Many metals like carbon steel,  aluminum alloys, copper, and brass stainless steel are very good for large batch of parts manufacturing; while whether you choose the cold forming process or not depends on your ultimate parts requirements such as strength and precision.

 

 

 

 

 

 

Case Study: Secondary CNC Machining Optimization for Cold-Formed Components 

 

 

A client from the automotive industry approached VMT CNC Machining Factory to perform secondary CNC machining on high-volume stainless steel cold-formed shoulder bolts. While the initial cold-forming process successfully created the "near-net shape" and significantly reduced raw material costs, it fell short of the final engineering requirements. Specifically, the cold-heading process could not achieve the critical shoulder diameter tolerance of ±0.01mm. Additionally, the design required a high-precision radial cross-hole in the head and a surface roughness of Ra 0.8 to ensure low-friction performance during final assembly.

 

To address these stringent precision demands, the VMT technical team developed a specialized secondary machining workflow. We utilized high-performance 4-axis CNC Swiss-type lathes equipped with automatic loading systems to perform secondary clamping and finishing on the cold-formed blanks. By employing custom high-hardness PCD (Polycrystalline Diamond) tooling for high-speed micro-cutting, we successfully mitigated the precision fluctuations typically caused by the work-hardening of stainless steel. Furthermore, we utilized CNC live tooling to complete the radial drilling and chamfering in a single setup, ensuring perfect symmetry and positional accuracy relative to the central axis.

 

By implementing VMT’s secondary CNC machining solution, the first-pass yield for the 50,000-piece batch rose from the client's projected 85% to an outstanding 99.8%. Critical dimensional tolerances were consistently maintained within ±0.01mm, and the surface finish met all specifications. Ultimately, the client received parts that perfectly satisfied their precision assembly needs while achieving a 35% reduction in total unit cost compared to a full CNC turning process. This hybrid approach delivered the perfect synergy of high-volume efficiency and high-end precision.

 

 

 

 

 

FAQs

 

 

What is the meaning of cold forming?

 

Cold forming is a manufacturing process where metal is shaped at room temperature using high-pressure dies. Instead of cutting material away, the metal is forced to "flow" into the desired geometry, preserving material and increasing strength.

 

 

What is an example of cold forming?

 

A common example is the production of a standard steel bolt. A piece of wire is cut to length and then "headed" in a cold forming press to create the hexagonal head and the shank, followed by thread rolling to finish the piece.

 

 

What is the difference between hot forming and cold forming?

 

Hot forming involves heating the metal above its recrystallization temperature to make it easier to shape, which is ideal for very large or complex parts. Cold forming happens at room temperature, providing better surface finishes, tighter tolerances, and increased hardness through work hardening.

 

 

What are the fundamentals of cold forming?

 

The fundamentals rely on the material’s plasticity, the precision of the die design, and the immense pressure applied by the forming press. Success depends on the metal's ability to deform without fracturing while maintaining structural integrity.

 

 

Can stainless steel be cold formed?

 

Yes, many grades of stainless steel (like 304 and 316) are excellent for cold forming. However, they work-harden much faster than carbon steel, requiring high-tonnage equipment and specialized tooling to achieve the desired shape.

 

 

What are the advantages of cold forming?

 

Because cold forming produces no metal scrap, it requires less reprocessing, along with the associated costs of transportation, fuel, and labor—most of which are environmentally friendly.