Shear Nuts - Tamper Proof Security Nuts in Zamak 5 Zinc Alloy

Breakaway Nuts Designed to Prevent Tampering

Shear Nuts are conical nuts with coarse threads designed for a permanent installation where preventing tampering with the fastener assembly is important. Shear nuts get their name because of how they are installed. They require no special tool to install; however, removal will be challenging, if not impossible. Each nut consists of a conical section topped by a thin, threadless standard hex nut that snaps or shears off when the torque exceeds a certain point on the nut. The finished result resembles a Tri-Groove or Trident Nut, only it does not have the grooves for installation or removal.

Shear Nuts are commonly used on signs in hospitals, public spaces, playgrounds, schools, and correctional facilities to secure various equipment and protect against unwanted removal.

Zamak Zinc Alloy

Zamak is a zinc alloy family. The most common, Zamak 3, is an alloy of zinc and aluminum and the de facto choice for die casting. Zamak 5 is the same as Zamak 3 but with added copper for greater strength, hardness, and corrosive resistance at the expense of ductility. Zamak alloy has an excellent balance of physical and mechanic properties, superb castability, and long-term dimensional stability.

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Zamak 5 Break-Away Nut Specifications

Nut Sizes	Hex Drive	Torque Guide	Bottom Diameter (Max)	Pre-Installed Height	Nut Height
#10-24	7/16"	30-40 inch/lbs	0.4375"	0.390"	0.18"
1/4"-20	9/16"	50-60 inch/lbs	0.5625"	0.470"	0.22"
5/16"-18	5/8"	90-110 inch/lbs	0.6250"	0.500"	0.22"
3/8"-16	3/4"	140-150 inch/lbs	0.7500"	0.580"	0.25"
1/2"-13	1"	330-360 inch/lbs	1.0000"	0.750"	0.35"
5/8"-11	1-1/8"	330-360 inch/lbs	1.1250"	0.800"	0.37"

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Break-Away Shear Nut Installation Instructions

	Uninstalled Nut - Thread the nut onto the bolt or stud that you will be using it on.
	Tighten with a Wrench or Socket - Using a wrench or socket, tighten the hex portion of the nut until it reaches the optimal torque and snaps off.
	Finished Installation - After the hex portion snaps off, ony a tapered circular nut remains. Due to its shape, it cannot be grabbed by a wrench socket or gripping devices which makes it highly resistant to tampering or vandalism.

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FAQs

What are tamper-resistant nuts?

Tamper resistant nuts, otherwise known as security nuts, are pieces of hardware that function as a standard fastener nut. However, they are designed to be difficult, if not impossible, to remove unless a specific driver or heavy tools are used. They're used for anti-theft applications.

How do you remove security shear nuts?

Shear nuts are not designed to be removed. If they were, they wouldn't make very good security nuts! That being said, if they must be removed, one option would be to use a grinder and cut grooves into the sides of the shear nut so that you could grip it with some pliers or vise grips.

What is a shear nut?

Shear Nuts are conical nuts designed for a permanent installation where preventing tampering with the fastener assembly is important. The conical section is topped by a thin, threadless, standard hex nut that snaps or shears off when the torque exceeds a certain point on the nut. This leaves behind the conical nut, which is very difficult to grip and remove.

How do shear nuts work?

The conical section of the shear nut is topped by a thin, threadless, standard hex nut that snaps, shears off, or breaks away when the torque exceeds a certain point on the nut. This leaves behind the conical nut, which is very difficult to grip and remove.

What is Zamak used for?

Zamak is used in many applications such as plumbing fittings, zippers, staplers, handles, locks, die-cast toys, sheet metal tooling, automotive parts, and some firearms, to name a few.

What is meant by die casting?

Die casting is a metal casting process in which molten metal is forced under pressure into a mold cavity. Zamak 3 is the most frequently used alloy for die casting in North America.