What do the numbers on a bolt head mean?
English bolts have radial lines on their head to identify the grade, or strength class. The number of lines on the bolt head is 2 less than the actual grade. So, for example, a grade 5 bolt will only have 3 radial lines on its head.
What do the head markings on a screw and bolt mean?
Screw and bolt head markings identify the manufacturer of the fastener and the standard to which the fastener was made. Below, we’ll explore both of those concepts, then connect them together with a few examples.
What is the difference between Grade 8 and metric bolts?
A grade 8 bolt will have 6 radial lines on its head. Metric bolts are a bit more straight forward, usually having their strength class number stamped right on the bolt head. Some metric nuts also have the strength class number stamped on their face. The below diagram shows examples of English and Metric bolt and nut markings.
How can you tell how strong a bolt is?
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 do letters on bolts mean?
The markings can identify the standard to which the bolt was made. For instance, if a bolt head contains three radial lines, then it's a Grade 5 bolt. If it contains five radial lines, then the bolt is Grade 8.
What does Ty 8.8 on a bolt mean?
So, in English, a Property Class 8.8 bolt is a bolt with a nominal tensile strength of 800 MPa and a nominal yield strength that is 80% of that nominal tensile strength, so 640 MPa.
What do the numbers on the head of a 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.
What do the numbers and letters on bolts mean?
Each grade has a specific bolt strength. No matter the system used to grade the bolts, the higher number means the stronger the bolt. For most home and automotive applications, you won't need anything more than a grade 8 bolt strength or metric class 10.9.
What size is a Ty 8.8 bolt?
Bolt Grade Markings and Strength ChartGrade and MaterialNominal Size Range (inches)Class 8.8 Medium carbon steel, quenched and temperedAll sizes below 16mm16mm - 72mmClass 10.9 Alloy steel, quenched and tempered5mm - 100mm19 more rows
What's the strongest grade bolt?
grade 8Grade 9 structural bolts, also known as grade 9 hex cap screws, are one the strongest structural bolts that can be used today. While the typical grade 8 bolt has a tensile strength of 150,000 PSI, a grade 9 bolt has a tensile strength of 180,000PSI.
How do I identify my bolt manufacturer?
Manufacturer's identification mark, e.g., “X” ( on head of bolts and screws and on one end of studs and stud bolts). Manufacture's identification mark, e.g., “X”, applied to head (raised or depressed at option of manufacturer).
How do I identify a bolt?
0:1019:06How to Measure and identify Bolts - YouTubeYouTubeStart of suggested clipEnd of suggested clipWhich is the thickness of the bolt. The second one will be the thread pitch and the third one willMoreWhich is the thickness of the bolt. The second one will be the thread pitch and the third one will be the length or how long the bolt is.
How do you read a bolt?
0:212:23How to Measure Screws & Bolts - US & Metric Sizing | Fasteners 101YouTubeStart of suggested clipEnd of suggested clipSo when you read a bolt that says quarter 20 by 2 that means quarter inch diameter 20 TPI that'sMoreSo when you read a bolt that says quarter 20 by 2 that means quarter inch diameter 20 TPI that's threads per inch which would be here.
How do you read bolt numbers?
Whether metric or standard, all bolts are sized by diameter, thread pitch, and length—in that order. So, for example, an SAE 1/2-16 x 2 bolt is ½" in diameter, has 16 threads per inch, and is 2" long. An M12-1.5 x 50 metric bolt is 12mm in diameter, has a thread pitch of 1.5mm, and is 50mm long.
What does M stand for in bolts?
The letter 'M' indicates that this bolt uses a metric thread. The number '8' refers to the nominal diameter of the bolt shaft in millimeters. The number 1.0 is the thread pitch of the bolt, which is the distance between threads, in millimeters. And the final figure, 20, is the length in millimeters.
How can you tell if a bolt is metric or standard?
0:4920:00How To Identify Bolts (US Standard and Metric) - YouTubeYouTubeStart of suggested clipEnd of suggested clipThis one has three slashes on the top of it or hash marks those are called that indicates that it'sMoreThis one has three slashes on the top of it or hash marks those are called that indicates that it's a sae a standard size bolt.
How to tell the strength of a bolt?
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. English bolts have radial lines on their head to identify the grade, ...
Why do English bolts have radial lines?
The higher the grade, the stronger the bolt. English bolts have radial lines on their head to identify the grade, or strength class. The number of lines on the bolt head is 2 less than the actual grade. So, for example, a grade 5 bolt will only have 3 radial lines on its head.
How many radial lines are there on a grade 8 bolt?
A grade 8 bolt will have 6 radial lines on its head. Metric bolts are a bit more straight forward, usually having their strength class number stamped right on the bolt head. Some metric nuts also have the strength class number stamped on their face. The below diagram shows examples of English and Metric bolt and nut markings.
Why use torque on bolts?
Many vehicle manufacturers use torque to yield bolts; especially on engines with aluminum heads and or in conjunction with (MLS) head gaskets. They provide more consistent clamping loads, across the entire head-to-block mating surface. When a shop manual indicates that a bolt is to be discarded and new ones used;
What is the first step in tightening?
While the first step in the tightening process is normally stated as a torque figure it is done so; only to provide a uniform baseline from which the true load is then applied. This is commonly referred to as a preload or snug torque.
Did we need cylinder heads in the 1960s?
We didn’t need them in the 1960′s or 70′s! The simple answer is engine materials are different. Aluminum cylinder heads expand at a different rate than cast iron blocks. As an engine warms up, bolted together parts have to move against each other or slide on their gaskets.
Do bolts stretch?
Bolts are elastic by nature, meaning that within their elastic range; they’ll stretch as load on the bolt increases. Typical bolts can be an issue when you use them on aluminum heads and; with a gasket that doesn’t relax, like an (MLS) gasket. The expansion rate of aluminum heads will stretch typical bolts, past their yield point and can snap them.
Proof Load
It is defined as the maximum tensile force that can be applied to a bolt that will not result in plastic deformation.
Yield Strength
Maximum load at which a material exhibits a specific permanent deformation or plastic deformation.
Tensile Strength
Tensile strength is a measurement of the force required to pull something such as rope, wire, or a structural beam to the point where it breaks.
What Does a Grade Mean?
The grade of your industrial fasteners not only determines how much stress they can stand but also why the type of tool must be used to tighten them.
