J-System hex head stud bolt DIN933 8.8 ZN M8 x 50

You use a full-thread tap bolt mainly when you want to connect parts in a pre-tapped hole or together with a nut, and the thread is needed over its full length. This is common in metalworking, construction, machine building and installation work. For the connection you usually also need a nut and a washer; the usual tools are an open-ended or ring spanner or a socket wrench.

What do DIN 933, 8.8 and ZN mean?

DIN 933 is the standard for hexagon bolts with full thread. The number 8.8 indicates the strength class and says something about how much load the bolt can handle; 8.8 is widely used for general structural applications. The abbreviation ZN stands for a zinc coating, which protects the steel against rust. For outdoor use or in a damp environment, a zinc coating offers limited protection; in that case, choose a stainless steel (RVS) version if needed.

How to choose the right length and diameter

For M8x50, 8 is the diameter in millimetres and 50 is the length of the threaded section. Add up the thickness of the parts to be joined, the washer and the nut, and choose a bolt whose end protrudes a few threads through the nut after tightening. If you are in between sizes, a shorter or longer size from the same range is often a good choice. On the page you will find related sizes, such as M8x70.

What should you look out for when mounting?

Always use nuts and washers with the same thread size and a suitable strength class, so the connection is as strong as the bolt. Tighten the bolt evenly and not harder than necessary, to prevent damage to the thread. If you want to secure bolts against loosening, you can use a locking washer or a self-locking nut.

Frequently asked questions

What is the difference between a tap bolt and a hexagon bolt with half thread?

With a tap bolt (DIN 933) the thread runs along the full length of the bolt. With a half-thread bolt, part of the shank remains smooth.

Which nut fits an M8 bolt?

An M8 hexagon nut, with the same thread size. For a bolt of class 8.8, preferably choose a nut with a matching strength class.

Is a zinc coating suitable for outdoor use?

A zinc coating provides basic protection against rust. For heavy outdoor use or in a damp environment, a stainless steel (RVS) version is usually better.