In the vast system of industry, fasteners, though seemingly small, are the core components ensuring the integrity and functional stability of the overall structure. Whether it’s precision electronic products, heavy machinery, or cross-sea bridges and aerospace vehicles, all rely on key components such as bolts, nuts, and screws for reliable connections. Correctly selecting fasteners directly affects the safety, reliability, and service life of products. So, faced with a dazzling array of products, how can one accurately select reliable and suitable industrial fasteners?
Select Based on Material Properties
Material is the fundamental factor determining the mechanical properties and applicable environments of fasteners.
Carbon Steel Fasteners
As the most commonly used and economical choice, carbon steel fasteners are usually marked with specific performance grades (such as 6.8, 8.8, 10.8). The higher the number, the higher the strength. Grade 8.8 and above are generally referred to as high-strength bolts.
Stainless Steel Fasteners
Stainless steel fasteners are renowned for their excellent corrosion resistance. 304 stainless steel is commonly used in general corrosion-resistant environments, while 316 stainless steel, containing molybdenum, offers superior resistance to acids, alkalis, and chloride corrosion, making it particularly suitable for harsh environments such as chemical plants and coastal areas.
Alloy Steel Fasteners
By adding elements such as chromium and molybdenum to carbon steel, alloy steel fasteners possess higher strength, toughness, and high-temperature resistance, and are commonly used in critical load-bearing components of heavy machinery and engines.
Selection Recommendation: Choose the appropriate material type based on the degree of corrosion and strength requirements of the operating environment.
Selection based on specifications, size, and performance grade
In the fastener field, “a small difference can lead to a huge error” is an unchanging rule.
Key Thread Parameters
The diameter, pitch, and length must be accurately measured or specified. Fine threads offer better anti-loosening performance and fine-tuning capabilities than coarse threads, but require higher assembly precision.
Coordinated Design of Size and Strength
In space-constrained situations, simply choosing small-sized bolts is not advisable. The correct approach is to select bolts with higher performance grades to compensate for the loss of load-bearing capacity due to size reduction. For example, a high-strength, small-sized bolt may save more space and meet load requirements than a low-strength, large-sized bolt.
Selection Recommendation: Ensure the thread parameters perfectly match the fastener, and determine the optimal combination of size and performance grade based on load calculations and installation space.
Select based on corrosion resistance requirements.
Surface treatment not only affects aesthetics but also determines the long-term performance and service life of fasteners in specific environments.
Electro-galvanizing
This is the most common and cost-effective treatment, offering a good appearance and general rust prevention. However, the zinc layer is relatively thin, and “white rust” may develop in humid environments, making it unsuitable for long-term outdoor or harsh environments.
Hot-dip galvanizing
The coating is thicker, with durability and corrosion resistance far exceeding electro-galvanizing, making it ideal for outdoor structural components such as power towers and guardrails. However, the surface is rougher, tolerance control is poorer, and it is not suitable for high-strength bolts.
Oxidation Treatment
This involves forming a dense oxide film on the surface, typically resulting in a black color. While its inherent rust-resistant capabilities are generally limited, it is often impregnated with rust-preventive oil after treatment. It is primarily used inside equipment and in environments requiring high dimensional accuracy and operating in dry conditions.
Selection Recommendation: Choose a matching anti-corrosion treatment method based on the degree of environmental corrosion (e.g., ordinary indoor environments, high humidity environments, coastal salt spray, chemical corrosion, etc.). In extremely humid or corrosive environments, directly using stainless steel or alloy steel is often a more fundamental solution.
Summary: Selecting suitable industrial fasteners is a systematic decision-making process that requires comprehensive consideration of four core factors: material, mechanical properties, dimensional accuracy, and the operating environment. Only by fully understanding these factors can you find the safest, most economical, and long-lasting connection solution for your project.
