Discover the Strongest Bolt Grades and Dyno Test Results
Table of Contents
- Introduction
- Understanding Bolt Grades and Classes
- Testing Bolt Strength
- Testing Bolt Hardness
- Conclusion
- Resources
Introduction
Welcome back to the Torque Test Channel! In today's video, we will be diving into the world of bolt grades and testing their strength and hardness on the dyno. Bolts come in various grades and classes, each with different strength ratings and hardness levels. We will explore the different grades and classes of bolts, test their strength claims, and determine if buying a higher-grade bolt means it can handle more impact. Additionally, we will take a closer look at stainless steel bolts and investigate their strength capabilities. So let's get started and find out which bolts can withstand the most torque!
Understanding Bolt Grades and Classes
Bolts are classified into different grades and classes to indicate their strength and hardness. Let's explore the various bolt grades and classes in detail.
Grade A or Grade 1 Bolts
Grade A or Grade 1 bolts are the lowest-rated bolts in terms of strength. These bolts are made from low to medium carbon steel, and they have a proof to tensile strength ranging from 33,000 to 60,000 psi. While these bolts are inexpensive, they are not suitable for applications requiring high strength. Grade A or Grade 1 bolts are often used in general construction where minimal strength is required. However, it's important to note that they have limited load-bearing capacities.
Pros:
- Inexpensive
- Suitable for applications requiring minimal strength
- Widely available
Cons:
- Limited load-bearing capacity
- Not suitable for high-stress applications
Grade 5 or Class 8.8 Bolts
Grade 5 bolts, also known as Class 8.8 bolts, are commonly used in automotive and machinery applications. These bolts have higher strength ratings compared to Grade A bolts, with a proof to tensile strength ranging from approximately 85,000 to 120,000 psi. Grade 5 bolts are made from medium carbon steel, and they are heat-treated to increase their strength. These bolts are typically marked with three lines on the head to indicate their grade or class.
Pros:
- Higher strength compared to Grade A bolts
- Suitable for automotive and machinery applications
- Widely available
Cons:
- Not as strong as higher-grade bolts
Grade 8 or Class 10.9 Bolts
Grade 8 bolts, also known as Class 10.9 bolts, are the most commonly used high-strength bolts. These bolts are made from medium carbon steel or alloy steel and have a proof to tensile strength of approximately 120,000 to 150,000 psi. Grade 8 bolts are significantly stronger than Grade 5 bolts, making them suitable for applications requiring higher torque and load-bearing capacities. They are often marked with six lines on the head or the number 10.9 to indicate their grade or class.
Pros:
- High strength and load-bearing capacity
- Suitable for demanding applications
- Widely available
Cons:
- Slightly more expensive than Grade 5 bolts
Class 12.9 Bolts
Class 12.9 bolts are among the highest-strength bolts available. These bolts have a proof to tensile strength ranging from 170,000 to 180,000 psi. Class 12.9 bolts are made from through-hardened alloy steel, and they are often used in critical applications where maximum strength is required. They are typically marked with a "B" on larger bolts or an insignia symbol on smaller bolts. Class 12.9 bolts offer exceptional clamping force and are highly resistant to stretching or wearing.
Pros:
- Exceptional strength and load-bearing capacity
- Ideal for critical applications
- Resistant to stretching or wearing
Cons:
Bowmaloy Bolts
Bowmaloy bolts, manufactured by MSC, are high-end, specialty bolts known for their superior strength. These bolts are made from through-hardened alloy steel and are designed to surpass the strength of Class 12.9 bolts. Bowmaloy bolts have a proof to tensile strength of 200,000 psi, making them ideal for heavy-duty applications that require extreme torque. They are often marked with a "B" on the head of larger bolts or an illuminati-like insignia on smaller bolts.
Pros:
- Exceptional strength surpassing Class 12.9 bolts
- Ideal for heavy-duty and high-torque applications
Cons:
- Expensive compared to other bolt grades
Stainless Steel 18-8 Bolts
Stainless steel 18-8 bolts are a type of bolt made from 303 or 304 stainless steel. These bolts are known for their corrosion resistance and are often used in marine applications. While stainless steel bolts are perceived to be stronger due to their bright and shiny appearance, their exact strength is not well-defined. Spec sheets mention a minimum strength of 65,000 psi but state that typical strengths range from 100,000 to 150,000 psi, similar to Grade 2 to Grade 5 bolts. Stainless steel 18-8 bolts are more expensive than other bolt grades.
Pros:
- Corrosion-resistant
- Suitable for marine applications
Cons:
- Exact strength varies and is not well-defined
- More expensive than other bolt grades
Testing Bolt Strength
To evaluate the strength of different bolt grades, we conducted tests using a dyno. We measured the amount of torque each bolt could handle before failure. Let's take a look at the results of our strength tests for each bolt grade.
Grade A or Grade 1 Bolt: During our testing, the Grade A bolt reached a maximum torque of 84 foot-pounds, which exceeded the recommended tightening torque of 32 foot-pounds. However, it failed to handle higher torque due to its low strength and softness.
Grade 5 or Class 8.8 Bolt: The Grade 5 bolt, also known as a Class 8.8 bolt, reached a maximum torque of 165 foot-pounds, surpassing the Grade A bolt by a significant margin. Even at this torque level, the Grade 5 bolt showed no signs of damage. However, when subjected to the impact of the Thor gun, it snapped in half.
Grade 8 or Class 10.9 Bolt: The Grade 8 bolt, equivalent to a Class 10.9 bolt, demonstrated even higher strength. It reached a torque of 213 foot-pounds with the Milwaukee impact wrench. However, when exposed to the force of the Thor gun, the Grade 8 bolt failed at a higher torque of 245 foot-pounds.
Class 12.9 Bolt: The Class 12.9 bolt, known for its exceptional strength, withstood a maximum torque of 230 foot-pounds with the Milwaukee impact wrench. When subjected to the Thor gun, it surpassed the Grade 8 bolt and reached a torque of 229 foot-pounds before failure.
Bowmaloy Bolt: The Bowmaloy bolt, designed to surpass Class 12.9 bolts in strength, demonstrated impressive performance. It achieved a torque of 253 foot-pounds with the Milwaukee impact wrench and held on without failing. When tested with the Thor gun, it reached a maximum torque of 245 foot-pounds before breaking.
Stainless Steel 18-8 Bolt: The stainless steel 18-8 bolt exhibited a torque of 179 foot-pounds with the Milwaukee impact wrench and 161 foot-pounds with the M18. It showed good resilience and did not fail under the applied torque. However, further testing is required to determine its maximum torque resistance.
Testing Bolt Hardness
In addition to strength, we also measured the hardness of the different bolts. Hardness is an important factor in determining a bolt's resistance to wear and deformation. Here are the hardness measurements of each bolt grade:
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Grade A or Grade 1 Bolt: Rockwell B scale hardness testing rated the Grade A bolt between 33 and 36. This indicates relatively low hardness compared to other bolt grades.
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Grade 5 or Class 8.8 Bolt: The Grade 5 bolt exhibited a hardness rating of approximately 35-36 on the Rockwell C scale, which is typical for bolts of this grade.
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Grade 8 or Class 10.9 Bolt: The Grade 8 bolt had a hardness measurement of around 35 on the Rockwell C scale, indicating a similar hardness to Grade 5 bolts.
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Class 12.9 Bolt: The Class 12.9 bolt demonstrated a hardness rating of about 41.8 on the Rockwell C scale, within the specified range for this class of bolt.
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Bowmaloy Bolt: Hardness testing revealed a hardness rating of approximately 45.3 on the Rockwell C scale for Bowmaloy bolts, indicating a higher hardness compared to other bolt grades.
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Stainless Steel 18-8 Bolt: Unfortunately, we were unable to obtain a hardness reading for the stainless steel 18-8 bolt. Further testing is required to determine its hardness properties accurately.
Conclusion
In conclusion, selecting the appropriate bolt grade is crucial for applications requiring varying levels of torque and load-bearing capacities. Based on our tests, higher-grade bolts such as Grade 8, Class 12.9, and Bowmaloy demonstrated superior strength and showed resistance to stretching or wearing. However, it's important to consider the specific requirements of your application before choosing a bolt grade. Stainless steel 18-8 bolts, while known for their corrosion resistance, do not have a clearly defined strength rating and require further testing to determine their capabilities accurately. Remember to consult the manufacturer's specifications and torque recommendations for the specific bolts you are using to ensure proper installation and optimum performance.
Resources
