Nuts

Stainless steel nuts in A2 (304) and A4 (316), from M1 to M64, plus imperial UNC, UNF, BSW, BSF and BA threads. A few sizes also come in duplex (1.4462) stainless.

• Hexagon nuts: full nuts to DIN 934 and ISO 4032, thin nuts to DIN 439 and ISO 4035, jam nuts, and left hand thread nuts.
• Locking nuts: nyloc (nylon insert) nuts to DIN 985 and DIN 982, all-metal prevailing torque nuts, castle nuts for split pins, and flange nyloc nuts.
• Dome nuts: domed cap nuts to DIN 1587 and domed nyloc nuts to DIN 986.
• Wing, flange and square nuts, including serrated and non-serrated flange nuts to DIN 6923.
• Specialist nuts: connector nuts for threaded rod, weld nuts, eye nuts, shear nuts, channel and cage nuts, T-nuts and sleeve nuts.

Use a full nut for general bolted joints, a locking nut where vibration could loosen it, and a dome nut to cover an exposed thread end.

Frequently asked questions

What is a nyloc nut?

A nyloc nut, also called a nylon insert lock nut, is a hex nut with a ring of nylon set into the top. The nylon grips the bolt thread and resists vibration that would loosen a plain nut over time. Simfix stocks nyloc nuts to DIN 985 and the taller DIN 982 in A2 (304) and A4 (316), from M2 to M36, plus flange and domed versions.

What is a dome nut used for?

A dome nut, made to DIN 1587, has a rounded cap that fully covers the end of the bolt thread. It gives a clean, snag-free finish on exposed threads and protects the thread tip. Simfix stocks dome nuts in A2 (304) from M3 to M30 and A4 (316) from M3 to M36, plus domed nyloc nuts (DIN 986) in A2.

What size nut fits an M8 bolt?

An M8 bolt takes an M8 nut; the number is the nominal thread diameter in millimetres, which matches across bolts, set screws and nuts of the same size. Standard metric nuts have a coarse thread, so check the pitch if your bolt has a fine thread. Simfix stocks M8 full, thin, nyloc, dome, flange, wing and castle nuts in both A2 (304) and A4 (316).

Should I use A2 or A4 nuts?

Use A2 (304) nuts for everyday indoor and general outdoor use. Use A4 (316) nuts near the coast, around pools or anywhere salt or chlorine is present, since A4 contains molybdenum, which resists chloride pitting that A2 does not. Match the nut grade to the bolt.

Sizes, grades and pack quantities vary by product type. Check the individual product listing for the exact specification and current availability.