Industrial Nuts and Bolts Manufacturing Process at a Glance

Nuts and bolts are fundamental elements in engineering and construction, but their manufacturing has evolved into a sophisticated and technologically complex process involving a large number of stages. The fasteners (nuts and bolts) produced and supplied by the top nuts and bolts manufacturing companies in India exhibit a diverse array of sizes and forms, however, the fundamental manufacturing method often remains the same. The process begins by cold forging steel wire into the desired form. This is followed by heat treatment to enhance its strength and surface treatment to enhance its durability. Finally, the product is packaged and prepared for shipping. However, for more intricate bolt designs, the manufacturing process may include many supplementary stages.

This blog explores the process by which raw steel is converted into precisely engineered metal tools:

Cold Forging

Cold forging refers to the process of shaping metal at room temperature using compressive forces. The process of cold forging starts by using sizable steel wire rods that are unwound and trimmed to the desired length. The steel grade is universally standardized across the industry, in accordance with the specifications outlined in ISO 898-1. The wire is then cold forged into the desired form using specialized tools. This process involves the shaping of steel at ambient temperature by using high pressure to force it through a sequence of dies.

The tooling is inherently intricate, including a maximum of 200 distinct components with tolerances as precise as hundredths of a millimeter. When cold forging is developed, it enables the rapid production of bolts in large quantities, while maintaining a high level of consistency. Almost all the top stainless steel bolts & nuts manufacturers in India adopt cold forging to carry out the fastener manufacturing process.

In cases when nuts and bolts designs are more intricate and cannot be shaped only by cold forging, further turning or drilling processes may be required. Turning is the process of rotating the bolt at a high velocity, during which steel is removed to obtain the desired form and design. Drilling is a method that may be used to create apertures in the bolt. Optionally, some bolts may be equipped with washers at this phase of the procedure.

Heat Treatment

Heat treatment is a conventional procedure adopted by all the largest industrial fastener manufacturers to manufacture industrial fasteners. In this process, the bolt is subjected to high temperatures to enhance the hardness of the steel. Threading is often performed prior to heat treatment, using either rolling or cutting methods when the steel is in a more malleable state. Rolling is a process similar to cold forging, where the bolt is passed through a die to shape and form the steel into threads. Cutting is the process of creating threads by eliminating steel by cutting.

Preemptively applying threading to the steel before heat treatment is a more efficient and economical approach, as it takes advantage of the subsequent change in steel characteristics that result in increased hardness. Nevertheless, performing threading subsequent to heat treatment will result in enhanced fatigue performance. Heat treatment may result in the formation of heat marks and minor damage to the nuts and bolts. Due to this rationale, several customers insist on threading being performed subsequent to heat treatment, particularly for applications such as engine and cylinder head bolts. The procedure is costlier since it requires the formation of hardened steel, but the threads will exhibit superior shape retention.

Heat treatment of lengthy bolts, with a length exceeding ten times the diameter, may cause the steel to return to its original round form, resembling the shape of the initial steel wire. Hence, it is often necessary to use a procedure of rectification.

Sizing and surfacing

The selection of surface treatment of the industrial nuts and bolts is dictated by the bolt's intended use and the specifications set by the client. Frequently, the first consideration for fasteners is their ability to resist corrosion. Thus, electrolytic zinc plating is a common solution. This process includes soaking the bolt in a zinc-containing liquid and applying an electric current to coat it with zinc. Nevertheless, electrolytic treatment does entail a heightened susceptibility to hydrogen embrittlement. Alternatively, zinc flakes may be considered since they provide superior protection against corrosion, albeit they come at a greater cost.

Phosphate is a more economically viable choice where corrosion resistance is not a concern, such as in the internal components of an engine or in applications that are often exposed to oil. After the application of the surface treatment, standard bolts are generally prepared for packaging by the largest industrial fastener manufacturers in India. Nevertheless, more sophisticated designs may need further assembly, such as the use of brackets. Additional bolts will need patching, either via the use of a locking patch or a liquid patch. A locking patch comprises a substantial nylon coating that is applied over the threads, enhancing the grip. Utilizing a wet patch will enhance the thread-forming torque.

Upon the completion of these processes, the bolt reaches its final state. Now, the only task left is to implement a quality control process to ensure standardization and coherence prior to packaging and shipping the bolts.

Concluding Remarks

Every industry needs nuts and bolts, whether it's manufacturing, construction, or aircraft. Their main purpose is to unite or fix two or more assembly or construction components. Fasteners like nuts and bolts determine the strength of many constructions and systems. Top nuts and bolts manufacturing companies in India employ several materials to construct industrial-grade fasteners. Industrial fasteners include nuts, bolts, nails, studs, and washers. Industrial fasteners like nuts and bolts are vital to practically all sectors, from manufacturing to aircraft.

The Closing Note

Caparo is one of the largest industrial fastener manufacturers in India providing supreme quality bolts & nuts for a wide range of applications across industries and sectors. Caparo is a strategic partner for customized fastener solutions to leading OEMs like Ashok Leyland, VECV, Royal Enfield, Honda Motors & Scooter, Escorts, Sonalika & many more. The company produces fasteners for a variety of international and Indian standards from cold heading quality of Medium Carbon, High Carbon, and alloy Steel.