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Bolts are super important in building and engineering stuff. They act as fasteners, holding everything from car parts to huge steel frames together. Knowing about different bolts, how they’re made, their strength levels, and how to read their specs is handy for engineers, mechanics.
A bolt is a threaded fastener. It slides through holes in parts to hold them tight. Usually, a nut is twisted on to secure it. Bolts come in all kinds of shapes and sizes. Most have a round, threaded rod with a head on one end. They team up with nuts to keep things firmly in place.
Telling bolts and screws apart can be tricky. The US Customs and Border Protection (CBP) Agency has a clear way to explain it. A bolt is a threaded fastener that goes through holes and gets tightened with a nut. A screw is threaded too, but it can fit into holes with matching threads or even carve its own. You turn a screw’s head to tighten or loosen it.
Cold forming shapes a bolt without heating the material. Workers press or hit it into a mold to get the right size. Hot forging heats the material until it’s soft and easy to shape. Then it’s molded. The method depends on the material, how precise it needs to be, and how many bolts are being made.
Bolt threads can be rolled or cut. Rolling squishes the material to form threads without removing any. This makes them tougher because the material hardens. Cutting uses tools like taps or dies to carve out threads from the material.
Heat treatment makes bolts stronger and tougher. Adding finishes like zinc plating or black oxide coating protects against rust. It also makes them look neat.
Hex bolts have a six-sided head. They’re really common in construction and machines.
Carriage bolts have a slim body and a big, round head. They’re often used in woodwork. A square part under the head stops them from spinning.
Flange bolts have a built-in washer under the head. This spreads out pressure when holding heavy stuff.
Eye bolts have a loop at the top. They’re great for hooking ropes or cables to lift heavy things.
U-bolts look like the letter “U.” They’re perfect for clamping pipes or tubes tight against a surface.
Also called lag screws, these sturdy fasteners go right into wood. They don’t need nuts to stay put.
Anchor bolts fix big parts to concrete bases. Often, they’re set while the concrete is still wet.
Stud bolts are threaded rods with no head. They use nuts on both ends and are common in flange connections.
Bolt grades show the material and how strong it is. They tell how much stress or pressure a bolt can take before breaking.
SAE grades are popular for inch bolts. The SAE J429 standard includes Grade 2, 5, and 8. Grade 2 is weaker, Grade 5 is medium strong, and Grade 8 is super tough for heavy jobs.
ISO standards, or metric standards, use property classes. Common ones for bolts are ISO 898-1 Property Classes 8.8, 10.9, and 12.9. Bigger numbers mean stronger bolts.
For inch bolts, you might see 5/8-11” X 4-1/2”. The 5/8 is the thread’s main width. The 11” means threads per inch. And 4½” is the bolt’s length from under the head.
M (Metric Coarse Thread) has a 60° thread angle. It’s used worldwide, except in North America. It’s written as nominal diameter x pitch, like M8x1.25.
For metric bolts, M8 means an 8-millimeter width. The 1.25 is the thread pitch, and 65MM is the length.
Need top-quality custom bolts for your project, like for big machines or pipeline setups? FLUIDO is a great pick. With ten years in casting and forging, they make pipe fittings, flanges, and valves based on your ideas. Besides their own flanges, FLUIDO works with factories in Shandong and Hebei for a wide range of products. All FLUIDO factories follow ISO9001 quality rules, so every batch is consistent anywhere it goes.
Whether you want standard hex bolts or something totally custom, FLUIDO offers great prices and tons of know-how. Reach out now by emailing info@fluidovalve.com or calling +86 532 88550858!
