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The Unsung Hero of Engineering: Metric-Hex Cap Screws (Class 8.8 Steel, Coarse Thread)

In the world of engineering and construction, fasteners are often the unsung heroes that hold everything together—quite literally. Among these, Metric-Hex Cap Screws, particularly those made of Class 8.8 steel with a coarse thread, stand out for their strength, reliability, and versatility. Whether you’re a professional engineer, a construction worker, or a DIY enthusiast, understanding the importance and applications of these screws can elevate your projects to new heights of durability and precision.

What Are Metric-Hex Cap Screws?

Metric-Hex Cap Screws are a type of bolt characterized by their hexagonal heads, which allow for easy tightening and loosening using a wrench or socket. The “cap” in their name refers to the head’s design, which sits on top of the material being fastened, providing a clean and professional finish.

Why Class 8.8 Steel?

Class 8.8 steel is a medium carbon steel that has been quenched and tempered, meaning it has undergone heat treatment to enhance its strength and toughness. This class of steel is the most commonly used for metric bolts, offering a good balance of strength, ductility, and cost-effectiveness.

Key Characteristics of Class 8.8 Steel:

  1. High Tensile Strength: Class 8.8 steel boasts a tensile strength of 800 MPa (megapascals), making it ideal for applications that require a robust hold.
  2. Durability: The quenching and tempering process increases the steel’s resistance to wear and tear, ensuring longevity even under high-stress conditions.
  3. Versatility: Suitable for a wide range of applications, from automotive and machinery to construction and structural components.

The Advantage of Coarse Threads

Coarse-threaded screws have fewer threads per inch compared to fine-threaded screws. This design offers several advantages:

  1. Stronger Hold in Softer Materials: Coarse threads are less likely to strip in materials like wood or plastic, making them ideal for general construction and repair work.
  2. Faster Installation: With fewer threads, coarse-threaded screws can be driven in quicker, saving time in assembly processes.
  3. Greater Resistance to Damage: Coarse threads are more robust and less susceptible to damage from handling and environmental factors.

Applications of Metric-Hex Cap Screws (Class 8.8, Coarse Thread)

  1. Automotive Industry: These screws are commonly used in vehicle assembly and repair, where high strength and durability are crucial.
  2. Machinery and Equipment: From industrial machines to household appliances, Metric-Hex Cap Screws ensure that parts remain securely fastened under operational stress.
  3. Construction Projects: They are essential in building frameworks, securing beams, and other structural applications where reliability and load-bearing capacity are critical.
  4. DIY Projects: For home improvements, furniture assembly, and hobbyist projects, these screws provide an easy-to-use and dependable solution.


Metric-Hex Cap Screws made from Class 8.8 steel with coarse threads are a cornerstone of modern engineering and construction. Their high tensile strength, durability, and versatility make them indispensable in a wide array of applications. By understanding their properties and benefits, you can make more informed choices in your projects, ensuring safety, efficiency, and longevity. Whether you’re constructing a skyscraper, repairing a vehicle, or building a new piece of furniture, these screws are the reliable backbone you need.

Embrace the strength and reliability of Metric-Hex Cap Screws, and let them be the foundation of your next successful project.