Square Nuts

A square nut, also known as a square head nut, is a four-sided nut designed for use with a square head bolt and flat washer. A square nut leaves sharp corners that can sometimes be destructive to the material surrounding the nut, but use with a flat washer provides protection from this, as well as a greater load distribution and increased strength. Most fasteners AFT offers meet ASTM A194, ASTM A563, or ASTM F594 standards. 

Frequently Asked Questions About Square Nuts

What are square nuts used for? 

Square nuts are frequently found in furniture manufacturing, vintage automobile restoration, railroad track construction, and in use as a blind nut. They are ideal for applications in tight spaces and repeated loosening/tightening cycles. 

What are the advantages of using square nuts? 

Square nuts’ most prominent advantage is their strong grip, which lends itself to a high-speed, low-stress installation and increased durability. 

What is the difference between a square nut and a hex nut? 

Other than the amount of sides the nut has, the main difference is that square nuts offer greater surface contact with the part being fastened compared to a hex nut, and therefore offers more grip and provides more resistance to loosening. 

What sizes do square nuts come in? 

AFT offers square nuts in both metric and SAE sizing. Diameter-thread sizes range from #4-40 to 1 1/2”-6 or M5-0.80 to M10-1.50.

What materials and finishes do square nuts come in? 

Square nuts are made of either steel or stainless steel, and come in hot dipped galvanized, plain, or zinc Cr+3 finishes (as well as custom finishes in our in-house plating department).