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.
2025-07-26 15:01:19
A machine screw is a type of fastener designed to be threaded into a pre-tapped hole or used with a Nut. Unlike wood screws or sheet metal screws, machine screws feature a uniform diameter along their entire length and are manufactured to precise dimensional tolerances, typically conforming to standards such as ISO 4762, ANSI B18.6.3, or DIN 912. These screws are commonly made from materials like carbon steel (Grade 2, 5, or 8), stainless steel (A2 or A4), or brass, with tensile strengths ranging from 60,000 psi (Grade 2) to 150,000 psi (Grade 8).
Thread Type: Machine screws feature unified (UNC or UNF) or metric (M3 to M12) threads with pitch diameters controlled within ±0.002 inches for precision fits.
Head Styles: Common head types include pan, flat, round, oval, and socket heads, with drive types such as Phillips, slotted, Torx, or hex.
Dimensional Accuracy: Shank diameters adhere to strict tolerances (e.g., ±0.001 inches for precision applications) with lengths ranging from 1/8" to 3".
Surface Treatments: Options include zinc plating (5-15µm), black oxide (0.5-1.5µm), or electropolishing (Ra 0.2-0.8µm) for corrosion resistance.
Torque Specifications: Recommended installation torque varies by size and material (e.g., 10-15 in-lbs for M4 steel screws).
Electronics Manufacturing: M2-M6 screws secure circuit boards with 0.5-3 N·m torque requirements, often featuring JIS B 1111 compliant anti-vibration threads.
Automotive Systems: Engine components use Grade 8 screws with 180,000 psi tensile strength, heat-treated to HRC 33-39.
Aerospace Assemblies: Titanium alloy screws (Ti-6Al-4V) meet NASM 21272 standards for airframe applications.
Medical Devices: 316LVM stainless steel screws with Ra ≤ 0.4µm surface finish for implantable devices.
Industrial Machinery: Large diameter (M12-M24) screws with DIN 933 threads for heavy equipment assembly.
Proper maintenance ensures optimal performance and longevity of machine screws:
Cleaning: Use ultrasonic cleaners with pH-neutral solutions (5-7 pH) at 40-60°C for 5-10 minutes to remove contaminants.
Lubrication: Apply molybdenum disulfide grease (NLGI Grade 2) or PTFE-based lubricants to reduce friction during installation.
Torque Verification: Periodically check fastener tension using ultrasonic measurement or calibrated torque wrenches (±2% accuracy).
Corrosion Prevention: For marine environments, specify A4 stainless steel with >500 hours salt spray resistance per ASTM B117.
Replacement Criteria: Replace screws showing >10% thread deformation or corrosion pits deeper than 0.1mm.
Always match screw thread pitch (1.25mm for M8 coarse thread) to the mating component
Use thread engagement length ≥ 1.5× diameter for optimal strength
Apply 30-50% of proof load during installation to prevent yielding
For critical joints, implement torque-angle control with ±5° precision
In high-vibration environments, use Nord-Lock washers or Loctite 263 threadlocker
| Material | Tensile Strength | Corrosion Resistance | Temperature Range |
|---|---|---|---|
| AISI 304 Stainless | 75,000 psi | Good | -200°C to 800°C |
| Alloy Steel (Grade 5) | 120,000 psi | Poor | -50°C to 250°C |
| Phosphor Bronze | 60,000 psi | Excellent | -100°C to 200°C |
Common failure modes and their technical indicators:
Fatigue Fracture: Beach marks at 45° angle with crack initiation at stress concentration points
Overload Failure: Cup-and-cone fracture with >5% elongation prior to rupture
Stress Corrosion: Intergranular cracking with chloride concentrations > 10ppm
Galling: Material transfer evidenced by Ra > 3.2µm surface roughness
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