# What does 8 8 mean on a metric bolt head?

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## What does 8 8 on a bolt mean?

You can usually figure out the grade, or strength, of a bolt by looking at the markings on its head. English bolts (U.S.S. or S.A.E) are categorized by grade, from grade 2 to grade 8, where the grade represents inch strength. The higher the grade, the stronger the bolt.

## What does 8.8 mean on metric bolts?

The grade 8.8 refers to the tensile strength which is generally 116,000 psi, grade 10.9 is generally 150,000 and grade 12.9 is generally 175,000 psi.

## What do the numbers on the head of a metric bolt mean?

In addition, most metric bolts are identified by a number stamped on the bolt head, such as 4.6, 5.8 or 10.9. The number has nothing to do with the size, but does indicate the relative strength of the bolt. The higher the number, the stronger the bolt. … A metric fastener could be designated M12 x 2, for example.

Determine the length of the metric bolt by looking at the third number. For example, if the metric bolt was M14x1. 5×25, it would have a length of 25 millimeters. Look on the bolt head for the number denoting the strength of the bolt.

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## Is Grade 8 or 12.9 stronger?

Table 1.

Metric Class 12.9 The highest metric class for strength, it exceeds Grade 8.

## Does M8 mean 8mm?

Hole Sizes for Metric Bolts

The defined diameter of metric bolts is actually slightly larger than the actual diameter of the bolt shaft. So an M8 bolt would have a shaft diameter that’s slightly under 8mm which means that the bolt should fit through an 8mm hole.

## What is the metric equivalent of Grade 8?

Metric Bolt Conversion

Metric Nut Class SAE J429 Normally Used Grades
8.8 8 5
9.8 9 5+
10.9 10 or 12 8
12.9 10 or 12 .

## How strong is a metric 8.8 Bolt?

Metric steel bolts, screws and studs – proof and tensile strength

Property Class Size Range (mm) Minimum Tensile Strength (106 Pa)
5.8 M5 – M24 520
8.8 M1.6 – M36 830
9.8 M1.6 – M16 900
10.9 M5 – M36 1040

## What are the markings on a Grade 8 bolt?

Commercial-grade 8 bolts are the strongest option available. They’re made from medium carbon alloy steel and have markings that include six raised dashes. The psi of the bolt is 150,000, meaning that it can withstand great deals of pressure because of the way it was quenched and tempered.

## What does the number stamped 8.8 on the top of this metric bolt mean?

Class 8.8: Head Marking: 8.8. Material: Medium carbon steel, quenched and tempered. Size Range: All sizes below 16-mm.

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## What is the shear strength of a Grade 8 bolt?

Shear strength of a grade 8 bolt in good condition is 91,000 psi.

## Will a 8mm bolt fit a 5 16?

Can I use a M8 bolt on a 5/16 thread? They look pretty similar at glance… Well, quick answer is no. They are not the same and they are not interchangeable, although they can work under certain circumstances.

## How do I know what size bolt I need?

So, determining the screw size is important. It is easy to determine the screw size. First, measure the diameter with a Vernier caliper. Choose the closest reading screw size on a screw thread gauge.