Specializing in the production of special precision screws and nuts of various standards such as Chinese standard GB, Japanese standard JIS, British BS, American ANSI and ISO.
At present, the smallest screw diameter that our company can produce is 0.4mm, the shortest is 0.4mm, and the longest is 300CM.
2025-07-19 16:35:14
Self-tapping screws are specialized fasteners designed to cut their own threads into pre-drilled or undrilled materials, eliminating the need for a separate tapping operation. These screws feature a sharp, hardened tip and unique thread geometry that allows them to create mating threads in softer substrates. The cutting action is achieved through either thread-forming (for plastic or soft metals) or thread-cutting (for harder materials) designs. Standard self-tapping screws typically have a tensile strength ranging from 60,000 to 180,000 psi, with thread angles between 30° to 60° depending on the application.
Thread Design: Asymmetric or tapered threads with a 15-30% larger major diameter than the pilot hole
Tip Geometry: Sharp gimlet points with 20-45° included angles for penetration
Hardness: Rockwell C scale ratings of HRC 28-45 for standard carbon steel variants
Self-tapping screws demonstrate exceptional penetration performance across various materials. In mild steel (ASTM A36), a #10 screw can typically penetrate up to 3.5mm without pre-drilling, generating 250-400 N·m of torque during installation. For aluminum alloys (6061-T6), the same screw achieves 5-6mm penetration with 150-280 N·m installation torque.
The thread-forming process creates 65-85% thread engagement in thermoplastics, with polycarbonate showing 12-15% higher pull-out resistance compared to ABS. In sheet metal applications (22-18 gauge), properly installed screws maintain 90-95% of their rated shear strength after repeated disassembly cycles.
Specialized thread designs like the Trilobe profile demonstrate 40-60% greater vibration resistance than standard threads in dynamic loading tests (per ISO 16130). Nylon-insert locking variants maintain 85% of clamp load after 5,000 vibration cycles at 50Hz.
Zinc-plated screws (5-8µm coating) withstand 96-120 hours in salt spray tests (ASTM B117), while stainless steel (A2/A4) variants exceed 1,000 hours. Recent ceramic-coated versions show 3-5x improvement over conventional zinc plating in cyclic corrosion testing.
In automotive body panels (0.8-1.2mm steel), self-tapping screws with Type AB threads provide 2,500-3,500 N tensile strength per fastener. HVAC ductwork installations utilize #8 to #14 screws with 1/4" hex heads for rapid assembly of 26-22 gauge sheet metal.
Electronics enclosures employ M3-M5 screws with 30° thread angles to prevent stress cracking in ABS and polycarbonate. The medical device industry prefers 316L stainless steel self-tappers with 0.5mm pitch for secure attachment of polymer components.
Decking screws feature #10-1/4" shanks with T-25 drive systems, achieving 4,500 lb withdrawal resistance in pressure-treated lumber. Specialized variants for engineered wood products incorporate double-lead threads that reduce installation torque by 25-35%.
Conduit fasteners use 1/4-20 thread-cutting screws that maintain 100 lb·ft clamping force in galvanized steel boxes. Panel-mount screws with shoulder stops prevent over-tightening in 12-10 AWG electrical connections.
Always match drill bit size to the screw's minor diameter (typically 70-90% of screw diameter). For hardened materials, use a 140° countersink to prevent edge chipping. Maintain installation speed below 1,500 RPM for steel screws or 800 RPM for stainless variants to avoid heat buildup.
Apply 0.1-0.3mL of anti-seize compound (containing 60-80% metallic solids) to threads in marine environments. For aluminum substrates, use zinc-aluminum coated screws to prevent galvanic corrosion. Inspect coastal installations every 6-12 months for white rust formation.
After 5-7 removal cycles, chase threads with a H3 tap to restore 75-80% of original holding power. In plastic applications, replace screws after 3-5 uses as thread-forming capability diminishes. Use thread inserts for frequently accessed panels in 10-12 gauge metal.
Maintain inventory at 30-50% RH with desiccant packs to prevent hydrogen embrittlement in high-strength alloys (>180,000 psi). Segregate stainless and carbon steel fasteners to avoid iron contamination. For long-term storage (>1 year), apply VCI paper or 0.5 mil corrosion inhibitor film.
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