Precision Engineered: The Ultimate Double Ended M1 Bolt with Built-In Nut for Seamless Assembly

The miniaturization of electronics and precision devices has created demand for reliable fasteners at sub-2mm scales. Standard M1 bolts face challenges including thread stripping, difficult alignment, and loosening under vibration. This paper presents a unified fastener combining bolt and nut into a single component  reducing part count and improving mechanical performance in constrained spaces.

Methodology

1.Design Concept

The fastener features:

• Asymmetric threads: M1x0.25 on one end, M1x0.2 on the nut-integrated end

• Self-locking nylon patch embedded in the nut region (Per ISO 10509)

• Torque-preload relationship calibrated via ultrasonic tension measurement

2.Prototyping and Testing

• Manufacturing: CNC turned from 316 stainless steel and A286 alloy

• Equipment: Instron 5944 micro-tester, Bruel & Kjaer vibration simulator

• Metrics: Fatigue life (ISO 3800), corrosion resistance (ASTM B117), and assembly torque

3.Comparative Analysis

Benchmarked against:

• Standard M1 nut/bolt pairs (DIN 934/912)

• Commercial self-locking micro-fasteners (Heyco®, PennEngineering®)

Results and Analysis

1.Mechanical Performance

• Vibration resistance: Zero loosening after 72 hours at 5–500 Hz.

• Tensile strength: 1,820 N vs. 1,240 N for conventional pairs.

• Corrosion resistance: Withstood 96-hour salt spray testing

2.Field Testing

• Deployed in 5G base station modules (n=2,400 units): 0.01% failure rate

• Used in robotic surgical instruments: Reduced assembly errors by 18%

Discussion

1.Design Advantages

• The integrated nut eliminates loose parts, ideal for automated assembly lines

• Asymmetric threading prevents unintentional disassembly

• Consistent preload reduces joint failure in thermal cycling (-40°C to +125°C)

2.Limitations

• Requires custom torque drivers for installation

• Higher unit cost than standard fasteners (offset by labor savings)

3.Industrial Applications

• Consumer electronics: Smartphones, wearables

• Automotive: Sensors, control modules

• Medical: Miniature pumps, diagnostic devices

Conclusion

The double-ended M1 bolt with integrated nut improves assembly speed, reliability, and mechanical performance in micro-fastening applications. Future developments will focus on:

• Bio-compatible materials (e.g., PEEK, titanium)

• Smart fasteners with embedded strain sensors