Nuts and Bolts: Overview, Qualitative Parameters, BIS Standards, and Materials

Nuts and Bolts: Overview, Qualitative Parameters, BIS Standards, and Materials

Be it manufacturing, construction, or aviation, nut and bolts are a part and parcel of every industry. They are the primary medium to join or fix two ore even more components in an assembly or structure. Nuts and bolts that are also known as fasteners play a very crucial role in determining the overall strength of a wide range of structures and assemblies.

Top nuts and bolts manufacturing companies in India make use of a wide range of materials to produce industrial-grade fasteners. Industrial fasteners denote a comprehensive range of items such as nuts and bolts, nails, studs, and washers. When it comes to nuts and bolts, they occupy a very important place among all industrial fasteners and are used in almost all industries right from manufacturing to aviation.

Bolt is a piece of rod with one end threaded and other end up-settled. As for nuts, they roll on the threaded part of the bolts. Nuts and bolts manufactured and supplied by the top nuts and bolts manufacturing companies in India are available in a very comprehensive shapes, sizes, and designs. Nuts and bolts serve fastening purposes particularly in those industries in which the replacement of parts and components is necessary.

It is the composition of materials that determines and controls the overall quality of the bolts and nuts (Fasteners). The recommended composition for industrial-grade nuts and bolts raw material includes the following:

  • Carbon - 0.22 to 0.23%
  • Phosphorus - 0.40%
  • Manganese - 0.39 to 0.60%
  • Sulphur - 0.50%.

Qualitative parameters of industrial and nuts and bolts

As far as the quality of the industrial nuts and bolts manufactured and supplied by the top nuts and bolts manufacturing companies in India is concerned, it needs to be strictly superlative. Industrial nuts and bolts need to be excellent in all aspects as they are used in very mission-critical applications.  Some manufacturers also provide custom manufactured products as per the exacting requirements of their customers.

Some of the important factors that are taken care of well during the manufacturing include the following:

  • A comprehensive analysis of the raw material is done
  • Raw material is finalized as per the type and classification of the product
  • Each nut and bolt is checked during every stage of manufacturing
  • A minute scrutiny is carried out keeping in view various critical product dimensions and forms
  • Necessary rectifications in the process cycle are also made if necessary
  • Final inspection is done as per the prescribed standard

The BIS has formed some standards for nut and bolts (fasteners) include the following:

  • IS 1363 - 1967 : Black hexagon bolts, nuts & lock nuts ( 6 – 39 mm)
  • IS 1367 - 1967 : Technical Supply Conditions for threaded fasteners
  • IS 4260 – 1967: Dimension of lengths and thread lengths for bolts, Screws and Studs
  • IS 4172 – 1967: Dimension of redials under the head of bolts and nuts etc.
  • IS 6623 – 1972: High tensile friction grip nuts, etc.

Testing facilities used for the nuts and bolts by the manufacturers who produce bolts & nuts for aerospace engines and other industries include the following:

  • Metallurgical Testing
  • Mechanical Testing
  • Chemical Analysis
  • Magnetic Particle Inspection (MPI)
  • Salt Fog Chamber and Failure Analysis
  • Tensile testing, and
  • Shear Testing, etc.

Some of the most commonly materials used to manufacture nuts and bolts

Material is the most significant factor in the manufacturing of the industrial nuts and bolts. The material selection depends upon a large number of factors. Manufacturers need to consider galvanic corrosion properties, resistance, strength, brittleness, and corrosion resistance desired in the nuts and bolts to be produced. Cost is also a critical factor while the manufacturers who produce bolts & nuts for aerospace engines and other industries choose the material.

Let’s take a look at the materials in detail:


Steel is one of the most common raw materials used by the top nuts and bolts manufacturing companies in India to produce industrial nuts and bolts. Most fasteners made using steel are plain but many of them are also available with different types of surface treatments such as chrome plating, zinc plating, and galvanization. As far as the grade of steel used is concerned, it varies based on the exacting requirements of the customers.

Alloy Steel

Manufacturers and suppliers of industrial-grade nuts and bolts use high strength alloy steel to produce industrial fasteners. To make these nuts and bolt even stronger, manufacturers give them heat treatment. The fasteners made using alloy steel are generally not plated and offer a very dull black finish. Such nuts and bolts offer unmatched strength.

It generally takes the following facility framework to heat treat the industrial nuts and bolts:

  • LPG & methanol Atmospheric base furnace
  • Auto control Panel CP1& CP2
  • Oxy probe base controller system
  • Carburizing and carbonitriding facility.


Chrome is the material that top nuts and bolts manufacturing companies in India use for plating and polishing the industrial nuts and bolts. Equipping the nuts and bolts with excellent corrosion resistance is the primary purpose of chrome plating but appearance is also very closely associated with chrome plating. This methodology is considered to be a little bit costly and as a result not much popular. Zinc plating is also very popular as part of the finishing exercise.

The Plating & Surface Coating equipment used are:

  • Automatic Zinc Phosphating Line
  • Hydrogen De-embrittlement Line
  • Automatic Zinc plating with PLC controller and all passivation
  • Zinc phosphating line PLC Controller
  • Based on the salt spray life requirement and the type of coating preferred by the customer, thickness is maintained.

The Closing Note

Caparo is one of the leading nuts and bolts manufacturing companies in India providing supreme quality bolts & nuts for aerospace engines and a wide range of other 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 & Alloy Steel.