You can source most standard and special fasteners from India, including hex bolts, screws, nuts, studs, washers, threaded rod, anchors and parts made to drawing. Common materials are carbon steel, alloy steel, stainless steel and brass.
Gujarat makers cover a lot of this range, with brass fasteners from Jamnagar and steel fasteners from Rajkot, Ahmedabad and other towns. Most plants specialise, so you may need more than one supplier.
The main product groups
- Hex bolts and hex screws in metric and inch sizes, in property classes from low strength to high tensile.
- Socket head cap screws, set screws and machine screws.
- Hex nuts, lock nuts, flange nuts and nylon insert nuts.
- Studs and stud bolts, including fully threaded stud bolts for flanges with matching heavy nuts.
- Threaded rod and bar for construction and general use.
- Flat washers, spring washers and lock washers.
- Anchors for concrete, such as wedge anchors, sleeve anchors and foundation bolts.
- Special fasteners made to drawing, such as wheel bolts, U-bolts and custom shoulder bolts.
How fasteners are made
Most small bolts and screws are cold forged on headers from wire. Larger or low-volume bolts are hot forged or machined from bar. Threads are usually rolled, which gives a stronger thread than cutting.
Cold forging needs dies and tooling for each size and head shape, so standard sizes run efficiently in volume. Specials made to drawing may need new tooling, which affects minimum order quantities and lead time.
High-strength fasteners are then hardened and tempered. Finally they are plated, coated or oiled. Each of these steps affects strength and corrosion life, so ask which ones the supplier does itself.
Standards and grades
Fasteners are ordered by dimension standard and strength grade. Dimension standards include ISO, DIN and ASME. Strength grades include ISO property classes such as 8.8 and 10.9, ASTM grades and stainless grades. These are covered in fastener grades and standards.
Coatings also matter. Zinc plating, hot-dip galvanising and zinc flake each give different protection, as explained in surface treatments for parts.
Points that cause trouble
- Head markings that do not match the grade, or that are missing.
- Hardness out of range because heat treatment was rushed or skipped.
- Hydrogen embrittlement in high-strength bolts that were electroplated without baking.
- Coating too thick on the threads, so nuts will not run on.
- Mixed lots in one carton, which breaks traceability.
- Carton labels that state a grade or standard the parts were never tested against.
Approvals for anchors
Construction anchors may also need a product approval in your market, such as a European Technical Assessment. Check this with your regulator before you sell them.
Next step
We find fastener plants that make your grades in-house, then have lots tested for hardness, strength and coating before loading. Book a free sourcing review to start.