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.
2025-08-15 10:31:25
A Machine Screw is a threaded fastener designed to be assembled with a pre-tapped hole or used in conjunction with a Nut. Unlike wood screws or sheet metal screws, machine screws feature uniform threading along their entire shank with precise dimensional tolerances (typically within ±0.013 mm for diameter and ±0.025 mm per 25 mm of length). These screws are manufactured to meet strict industrial standards such as ASME B18.6.3 or ISO 4762, with thread pitches ranging from 0.35 mm for M1.6 screws to 6.0 mm for M100 sizes.
Key technical specifications include:
Materials: Typically carbon steel (Grade 2, 5, or 8 with tensile strengths of 400-1500 MPa), stainless steel (A2/A4 with corrosion resistance up to 1000 hours salt spray testing), or brass (CuZn39Pb3 with 35% conductivity)
Head styles: Pan, flat, round, oval, or socket heads with drive types including Phillips, slotted, Torx (common sizes T10-T40), or hex socket (Allen) with torque capacities up to 50 Nm for M12 screws
Thread types: Unified (UNC/UNF with 60° thread angle), metric (M-series with 0.5-6.0 mm pitch), or special threads like Acme or buttress for specific applications
Machine screws serve critical functions across industries due to their precision and reliability:
Electronics Manufacturing: M1.6-M3 screws with 0.35-0.5 mm pitch secure circuit boards, with nylon or PEEK variants providing electrical insulation (dielectric strength up to 20 kV/mm)
Aerospace: Titanium alloy screws (Ti-6Al-4V) with 1100 MPa tensile strength and -200°C to 450°C operational range for airframe assembly
Automotive: High-strength steel screws (10.9 or 12.9 grade) with 100-120 ksi yield strength for engine components, often featuring prevailing torque locknuts (vibration resistance up to 5,000 cycles in DIN 65151 testing)
Medical Devices: ASTM F138 stainless steel screws with Ra ≤ 0.8 μm surface finish for implantable devices, sterilizable up to 134°C in autoclaves
Industrial Machinery: Large diameter screws (M24-M100) with 4.6-12.9 property classes for heavy equipment, often coated with zinc flake (720 hours neutral salt spray resistance) or Dacromet
Proper maintenance ensures optimal performance and longevity of machine screw assemblies:
Installation Best Practices:
Use calibrated torque wrenches with accuracy within ±3% of indicated value
Apply appropriate thread locking compounds (e.g., Loctite 243 with 10-20 Nm breakaway torque for M10 screws)
Maintain 70-80% thread engagement for optimal strength (calculated as [(Le × P)/D] × 100, where Le is engagement length, P is pitch, D is nominal diameter)
Preventive Maintenance:
Inspect screws every 500-1000 operating hours for signs of wear (thread deformation exceeding 10% of original profile) or corrosion (red rust covering >5% of surface area)
Re-torque critical connections after 24-48 hours of initial installation (typical relaxation loss of 5-10% preload)
For stainless steel screws in chloride environments, perform passivation with 20-50% nitric acid solution at 49-60°C for 20-30 minutes
Lubrication Guidelines:
High-temperature applications (>300°C): Use molybdenum disulfide (MoS2) with particle size 1-5 μm
Corrosive environments: PTFE-based lubricants with 0.1-0.3 mm coating thickness
Precision instruments: Dry film lubricants with 5-15 μm thickness to prevent contamination
Replacement Criteria:
Thread damage exceeding 30% of theoretical stress area (calculated as π/4 × (D - 0.9382P)2)
Head deformation causing >5° drive tool misalignment
Galvanic corrosion penetrating >0.1 mm into base material
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