Screw specifications mainly include nominal diameter (M value), pitch, length, head shape, drive method, and material grade. Different specifications correspond to different application scenarios. Choosing the right specification is key to ensuring connection strength and safety.
Comparison of Common Screw Types and Applicable Scenarios
External Hex Bolt
Specifications: Hexagonal head, requires a wrench or socket wrench for tightening, commonly M6~M30, length 10~200mm.
Application Scenarios:Heavy machinery, building steel structures, automotive chassis, and other applications requiring high torque tightening.
Internal Hex Bolt
Specifications: Cylindrical head + recessed hexagonal hole, commonly M3~M24, head can be recessed into the workpiece, smooth appearance.
Application Scenarios: Precision equipment, molds, furniture, electronic products, and other assemblies where space is limited or aesthetics are important.
Self-tapping screws
Specifications: Pointed-tail design, commonly ST2.2~ST6.3, no pre-tapping required, can be directly screwed into metal, plastic, or wood.
Applications: Appliance housings, sheet metal parts, plastic panels, light assembly, commonly used in DIY home improvement.
Set screws (e.g., set screws)
Specifications: Fully threaded, headless or small-headed, commonly M2~M10, used for axial positioning.
Applications: Anti-loosening fixing of transmission components such as motor shafts, gears, and couplings.
Counterhead screws
Specifications: Tapered head, flush with the surface after tightening, commonly Phillips head or slotted head.
Applications: Connections requiring a flat surface in woodworking, furniture, and decorative parts.
Expansion bolts
Specifications: Composed of a bolt and an expansion sleeve, commonly M6~M12, length 50~150mm.
Applicable scenarios: fixing brackets, hangers, equipment bases, etc. on concrete walls and brick walls.
