The miniaturization of electronics and medical devices has increased demand for reliable M1-sized fasteners. Traditional solutions require separate nuts and washers, complicating assembly in spaces under 5mm³. A 2025 ASME survey noted that 34% of field failures in wearables stem from fastener loosening. This paper presents an integrated bolt-nut system that addresses these issues through monolithic design and enhanced thread engagement.
Methodology
1.Design Approach
● Integrated Nut-Bolt Geometry: Single-piece CNC machining from 316L stainless steel with rolled threads (ISO 4753-1)
● Locking Mechanism: Asymmetric thread pitch (0.25mm lead on nut end, 0.20mm on bolt end) creates self-locking torque
2.Testing Protocol
● Vibration Resistance: Electrodynamic shaker tests per DIN 65151
● Torque Performance: Comparison with ISO 7380-1 standards using torque gauges (Mark-10 M3-200)
● Assembly Efficiency: Timed installations by trained technicians (n=15) across 3 device types
3.Benchmarking
Compared to:
● Standard M1 nut/bolt pairs (DIN 934/DIN 931)
● Prevailing torque nuts (ISO 7040)
Results and Analysis
1.Vibration Performance
● Integrated design maintained 98% preload vs. 67% for standard pairs
● Zero loosening observed at frequencies >200Hz
2.Assembly Metrics
● Average installation time: 8.3 seconds (vs. 21.8 seconds for conventional fasteners)
● 100% success rate in blind assembly scenarios (n=50 trials)
3.Mechanical Properties
● Shear strength: 1.8kN (vs. 1.5kN for conventional pairs)
● Reusability: 15 assembly cycles without performance degradation
Discussion
1.Design Advantages
● Eliminates loose nuts in assembly environments
● Asymmetric threading prevents counter-rotation
● Compatible with standard M1 drivers and automated feeders
2.Limitations
● Higher unit cost (+25% vs. conventional pairs)
● Requires custom insertion tools for high-volume applications
3.Industrial Applications
● Hearing aids and implantable medical devices
● Micro-drone assemblies and optical alignment systems
Conclusion
The integrated double-ended M1 bolt reduces assembly time and improves reliability in micro-mechanical systems. Future developments will focus on:
● Cost reduction through cold forging techniques
● Expansion to M0.8 and M1.2 size variants
Post time: Oct-10-2025
