Cold forming – material-saving and accurate workpiece production
How does the cold forming process work?
Cold forming is a process involving the plastic forming of metals in a press to gradually turn work parts into a defined shape by applying pressure. However, unlike the warm forming method, the process of plastic cold forming is carried out below the recrystallisation temperature. This causes a strain hardening within the structures of the metal resulting from an increase in the dislocation density in the crystal lattice. In its modified structure, the reshaped metal has improved, purpose-built properties.
As a manufacturer of quality high-tech products, we specifically exploit these material-affecting factors. In multiple steps, we carefully and precisely press metal blanks into the desired shape. The resulting locking bolts, latching screws, sleeves or bushings are undergo further refinement by galvanic surface treatment, pigment coatings, heat treatment or micro-encapsulation.
From lightweight aluminium to malleable brass
Steel in its many forms is of the most high-performing materials in the industry. The automotive industry is increasingly relying on the process of cold forming, not least due to the increasing demands placed on the quality of its components. In addition, Bilstein & Siekermann® supports the manufacturing process with approximately 300 cold-formed parts per minute. For example, for the automotive sector, locking bolts and latching screws are made from 35B2 steel, seat bases are made of C4C steel, and sleeves for sensors and belt attachments are made of C10C steel.
In the growth sector of aluminium, cold reforming makes valuable contributions to weight reduction. With the increasing demand for lightweight construction, aluminium, which is 70% lighter than steel, is increasingly replacing heavy steel, with aluminium pressings possessing enormous tensile strength, high corrosion resistance and great durability. Screws with similar coefficients of expansion to the surrounding material also produce lower pre-load losses, allowing shallow screw-in depths.
Brass pressings enable customers to influence material properties in a targeted manner through their particular alloys. Depending on your choice, high-grade copper alloy fittings are non-magnetic, immune to sparks, highly corrosion-resistant or have specific thermal and electrical conductivity properties. Cold forming allows brass alloys to be cold-formed up to a zinc content of 37%.
Benefits of cold forming
Strain hardening, which occurs during the plastic cold forming process, improves the material characteristics of the products produced by this method. Increasing the dislocation density of the crystal lattice extends the strain limit of a workpiece, increases its hardness and enhances its tensile strength. At the same time, strain hardening reduces the ductility of the metal.
Eliminating the adverse heat effects also eliminates the material loss and unsightly stains caused by surface scale. Cold formed parts therefore have good surface characteristics, which we further refine in a careful post-machining process.
The outstanding properties with respect to compliance with tight tolerances for the cold forming process are highly advantageous in high-tech industries. Multi-level presses produce parts at high speed with a low spread; perfect for mass production of industrial components.
The greatest value of cold forming is the efficiency of the manufacturing process. In addition to the high production rates, the reduction in material consumption compared to a machining process leads to significant savings. The knock-on effects include component cleanliness, environmental sustainability and efficiency.
Industries and applications
Whereas a huge amount of valuable feedstock is lost during rotating, milling, drilling, or sanding, cold forming is carried out with minimal material loss. This economic factor is used by producers in the high tech sector, in mechanical and plant engineering and in the automotive and aerospace industries.
Cold forming is an efficient alternative to conventional manufacturing methods, especially for lightweight magnesium, aluminium or plastic products. Screws hardened during the manufacturing process allow for a lower screw depth, which means additional material and weight savings.
Most importantly, it is the flexible processes and fast response times that make Bilstein & Siekermann® a popular partner in the automotive sector. Our surface-refined screws, bolts, sleeves and shafts enhance the appeal of visible areas and help ensure durability in hydraulic and drive technology.
Bilstein & Siekermann® – Intelligent solutions for products and processes
The ground-breaking cold forming method is one of the technologies that earned Bilstein & Siekermann® the title ‘Innovator 2018’ from the business magazine ‘brand eins Wissen’ and the company Statista GmbH. We ensure close cooperation between the development and engineering departments thanks to intelligent and innovative products and processes.
In addition, we provide expert advice and precise support when addressing our customers’ specific processes and needs. Over more than six decades, Bilstein & Siekermann® has gathered the necessary expertise that we now use today for process safety and the outstanding quality of our products.