SUMMER 2026

8 THE DISTRIBUTOR’S

8 THE DISTRIBUTOR’S LINK Rob LaPointe EXPEDITE TESTING SERVICE Rob LaPointe is a noted authority in materials and fastener technology. With extensive experience in the management and science of materials testing laboratories combined with master’s degrees in physics and education, he excels at bringing solutions to the client. Working specifically in the fastener testing industry, he has developed expertise in mechanical, nondestructive, metallurgical and chemical testing. With a background of 20 years in physics education, Rob is effective at communicating complex ideas in a simple and understandable manner, communicating well with clients enabling them to make informed decisions about their products and business. Rob is President/CEO of Expedite Testing Service, 11645 Riverside Drive, Suite 127, Lakeside, CA 92040. Tel: 619-736-7872, Cell: 909-254-1278 or visit www.expeditetest.com. FASTENER SCIENCE: UNDERSTANDING COMMON FASTENER GRADES AND STRENGTH RATINGS Growing up, the only fastener grade I knew about was Grade 8. Grade 8 bolts were commonly found in automobiles, which I spent a fair amount of time driving and fixing as a teen and young adult. Out of interest and the desire to recognize and understand the world around me, I learned the basic mechanical properties and head markings of the venerable Grade 8 so that I could understand which bolts could be a viable swop from the spare bolt bucket when an automotive fastener was broken or stripped. A trip to the hardware or auto parts store was only warranted if you didn’t have that item in your spare parts collection. I was raised by parents who survived the Great Depression. Maybe you can relate. I never faced any serious consequence of choosing the wrong strength fastener from my bucket of bolts to replace something on a vehicle or machine, but I’ve broken or stripped a few and, through those experiences, gained a sense of what works. My fastener knowledge didn’t grow significantly during my first professional career as a physics instructor, but I did gain significant knowledge in materials and mechanics during this time. When I got into the fastener industry as the General Manager of a materials laboratory, I began to solidly grow my fastener knowledge and the knowledge of physics helped to accelerate that process. Learning the basics of carbon and alloy steel fasteners in imperial and metric systems was extremely useful. Understanding the correlation between grades and classes provides deeper insight into the products we use and sell every day. It also reveals an underlying beauty and simplicity to what might seem complicated at first. TECHNICAL ARTICLE Material All the fasteners compared in this article are made from either carbon steel or alloy steel. The significant difference between the two being alloying element requirements for elements such as chromium and molybdenum. It’s amazing to consider that the only real difference between different strengths of these fasteners is the heat-treating process, chiefly the tempering component of the that process. Tempering temperature and time are the tuning that determines conformance to a grade or class. Tensile And Yield Strength What constitutes a grade or class of fastener? The most general answer to this question is strength. Grade (common in imperial fasteners) or class (common in metric fasteners) is a rating of strength. Strength is the amount of stress (pressure) that a material can withstand without permanent alteration of its shape which will eventually cause the material to rupture. These two values are called yield strength and tensile strength. The stress that causes a material to permanently distort is yield strength. This label is consistent with our common use of the word yield to infer giving way. When the material’s shape gives way to stress, this amount of stress is called the yield strength. FIGURE 1 GRADE 8 HEX CAP SCREW CONTINUED ON PAGE 86