J-System hex head stud bolt DIN933 8.8 ZN M8 x 70

The size reads as follows: M8 stands for a thread diameter of 8 millimeters and 70 stands for a length of 70 millimeters. That length is measured from the underside of the head to the end of the bolt, so the head itself is not included.

What do DIN 933, 8.8 and ZN mean?

DIN 933 is the standard for hex head bolts with full thread, also called tap bolts. Grade 8.8 indicates the strength class of the steel and is widely used for structures and machines where a strong connection is needed. ZN means the bolt is zinc plated, which provides basic protection against rust.

Choosing a hex head screw M8x70: length and application

When choosing the length, look at the total thickness of the parts to be joined. Include the thickness of a nut and washer, and make sure that a few threads still protrude from the nut after tightening. For a blind tapped hole, the bolt should not bottom out in the hole. Because the shank is fully threaded, you can also use the bolt if the length of the joint varies slightly.

Zinc plated or stainless steel?

Zinc plated steel is suitable for dry or sheltered indoor environments. Outdoors, in damp areas or in contact with aggressive substances, stainless steel is usually the better choice. On this page you will also find variants in other lengths and in A2 stainless steel, so you can easily compare.

Frequently asked questions

What is the difference between a stud bolt and a hexagon bolt with a shank?

A tap bolt has thread over its full length, a bolt with a shank has an unthreaded section under the head. Tap bolts follow DIN 933, bolts with a shank follow DIN 931.

Which nut fits an M8 bolt?

An M8 bolt requires an M8 nut with the same standard pitch. A hex nut usually fits, but always check the size and quality of the nut.

How is the length of a bolt measured?

The length is measured from the underside of the head to the end of the bolt. For M8x70 that is therefore 70 millimeters excluding the head.