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Decoding Grades 8.8, 10.9, and 12.9

Last updated: 8 Aug 2026
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Hex Bolt สกรูหัวหกเหลี่ยม 12.9 ยี่ห้อ EG

Ever wondered about those mysterious numbers on the Bolt's head? Let's dive into the world of high-strength fasteners and unravel the differences between grades 8.8, 10.9, and 12.9. Buckle up, DIY enthusiasts and engineering buffs we're about to get technical!

First, let's decode those numbers:

  1. The first digit (8, 10, 12) represents the screw's strength. Think of it as a multiple of 100 MPa.
  2. The second digit (8, 9, 9) is the ratio between the minimum tensile strength and yield strength.
  • Grade 8.8: Budget-friendly and widely available Perfect for everyday projects Not ideal for high-stress applications
  • Grade 10.9: Stronger than 8.8, great for medium-duty tasks Pricier than 8.8 Harder on threading tools if rework is needed
  • Grade 12.9: The strongman of screws excellent tensile strength, torque resistance, and impact tolerance The most expensive option Tough on threading tools (most manufacturers won't even attempt rework)

Choosing The compatible one:

  • Grade 8.8: Your go-to for woodworking, furniture assembly, and light machinery.
  • Grade 10.9: The middle-ground hero for general machinery applications.
  • Grade 12.9: The heavy-duty specialist for construction, automotive work, and high-risk or hard-to-maintain areas.
Pro Tips:

  • Match the grade to your project's needs (consider weight and shear forces).
  • Factor in environmental conditions and wear expectations.
  • When in doubt, consult an expert better safe than sorry!

Remember, choosing the right screw isn't just about strength it's about finding the perfect balance for your specific project. So next time you're facing the fastener aisle, you'll be armed with the knowledge to make the best choice.

Looking for your best fasteners click below:


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