Cold Forming

Characterization of Cold forming

Cold Forming – a manufacturing process with tradition

App. Stages of cold forming (Source: Moehling) — Stages of cold forming (Source: Moehling)

Cold forming refers to forming processes occurring significantly below the recrystallization temperature of the material. Generally, the initial component temperature is around room temperature. During cold forming, materials are plastically deformed through high compressive loads. This procedure changes the material properties, as well as the shape itself.

The most important manufacturing processes are classic cold heading and impact extrusion processes (e. g. for the manufacturing of fasteners and rivets), but also punching, hobbing, thread rolling, and drawing processes (wire drawing, tube drawing, pultrusion). Since we cover sheet metal and rolling processes in separate categories, here we will focus on cold bulk forming processes.

Cold forming processes are used in particular when the goal is to achieve ready-to-install geometries (netshape forming), low tolerances, and good surface properties. Compared to hot forming, the advantages can be shorter process times, higher surface quality, and improved mechanical properties. Due to the comparably low energy use, cold forming processes can be more economic, despite the required forming forces generally being higher than in hot forming processes. Cold forming is therefore restricted to easily formable materials, or rather materials which can easily be transferred into a formable microstructural state.

Cold forming results in strain hardening, meaning both the strength and resistance to forming increase with ongoing deformation. Thus, cold formed components can withstand greater operational loads. At the same time, strain hardening results in reduced formability (ductility) of the material. If the component needs to be formed further, the strain hardening of the component has to be removed via recrystallization annealing. Cold forming and annealing are often part of a multi-stage process.

Products and target sectors

Typical products and application fields

Typical cold forming products are, for example, screws, nuts, bolts, rivets, gears, shafts, and fittings.

These products can be used:

in the fastener and fittings industry
as electronics components (plugs, contacts, heat sinks)
in the automotive sector
in gear and engine manufacturing
as bicycle components
in minting
in heating engineering (conduit pipes)
in the tools industry
in mechanical engineering

The variety of cold forming products and their fields of applications substantial.

(Source: maho - Fotoalia.com)
Stages of cold bulk forming – gearing corrugation

Trends and Developments

Where is the development heading in cold forming?

Increasingly complex components
Ready-to-install press-fallen components
Materials with continuously higher basic strength should be formable
Reducing annealing steps
Gears need to be reliably manufactured
Composite components

Typical Problem definitions in Cold forming

From a business perspective, the consideration of dies, the particularly die life, is besides workpiece deformation highly relevant to cold forming.

The high yield stress and strain hardening result in very high press forces in the manufacturing process, and shift the focus to the used forming dies and die materials. The die life essential for cold forming is often only achievable through prestressed dies, which means that the simulation of cold forming has to consider the effect of the stress rings in addition to the material flow. The realistic mapping of forces in the forming processes, and the consideration of the effects of spring back, while taking into account the elastic-plastic material law, are indispensable for a high precision simulation of cold forming processes.

Our Software Solution for Cold forming

The Cold Forming Module in Simufact Forming

Use the advantages of Simufact.forming for your cold forming processes.

Simufact Forming Cold Forming addresses the simulation of bulk forming processes below the recrystallization temperature of the material. The module helps you to prevent common manufacturing errors such as:

Wrinkle formation
Markings created by shearing edges
Insufficient mold filling
Cracks
Excessive press and die loads

Simufact Forming Cold Forming considers all relevant boundary conditions, including the stress rings and the spring-mounted dies. The realistic prediction of the involved forming forces, while taking into account the spring back effects and the elastic-plastic material law, is indispensable for a high precision simulation of cold forming processes.

For a functional look at Simufact Forming Cold Forming, please read our product description:

Simufact Forming Cold Forming