Diaphragm(disc) couplings are flexible couplings that transmit torque and compensate for shaft misalignment through the elastic deformation of metal diaphragms. Disc couplings are widely used in the following scenarios:

High-Precision Transmission: Precision machine tools, turbomachinery, aircraft engines, etc.

High-Speed Rotating Equipment: Centrifuges, compressors, pumps, fans, etc., due to their excellent dynamic balancing performance.

Harsh Environments: High-temperature, corrosive environments (e.g., chemical equipment) or maintenance-free applications (e.g., offshore platforms).

Shaft Misalignment Compensation: Simultaneously compensates for axial, radial, and angular misalignment (single diaphragms handle angular and axial, while double diaphragms address radial).

Long Service Life Requirements: No wear-prone components (e.g., rubber elements), suitable for long-term operation.

Membrane Couplings Selection Methodology

1. Core Parameter Calculations

Torque: Calculate rated torque (based on motor power and speed): T=9550×PnT=9550×nP​ (unit: Nm, where PP is in kW and nn is in rpm).

Verify peak torque (e.g., during startup, braking, or shock loads).

Speed: The coupling’s maximum allowable speed must exceed the operating speed to avoid resonance or diaphragm fatigue.

Misalignment Limits:

Axial displacement: ±1–5 mm (varies by model).

Radial misalignment: 0.5–3 mm.

Angular misalignment: Typically ≤1°.

2. Environmental Adaptability

Temperature: Standard materials (e.g., stainless steel 304) suit -50°C to 250°C; high-temperature environments may require Inconel alloys.

Corrosion Resistance: Prioritize 316L stainless steel or nickel-plated surfaces in chemical environments.

Vibration and Shock: Opt for multi-layer thin-diaphragm designs with high fatigue strength for high dynamic loads.

3. Structural Type Selection

Single Diaphragm: Compact design for angular and axial compensation, limited radial capability.

Double Diaphragm: Enhanced radial compensation via an intermediate spacer, ideal for long shaft spans or complex misalignment.

Special Designs: Spacer-equipped couplings for thermal expansion isolation, or extended versions for large shaft gaps.

4. Installation and Dimensional Compatibility

Shaft Bore Types: Keyway (common), shrink disc (keyless), spline (high torque), or tapered bore (high alignment precision).

Size Constraints: Outer diameter must avoid spatial interference; lightweight designs are critical for aerospace applications.

Alignment Requirements: Minimize initial misalignment (e.g., ≤0.1 mm) to prolong service life, even though diaphragms tolerate some deviation.

5. Dynamic Performance Verification

Torsional Stiffness: High stiffness for servo systems (reducing hysteresis); low stiffness for vibration damping (e.g., diesel generators).

Critical Speed: Ensure operating speed stays clear of the coupling-shaft system’s critical speed to prevent resonance.

6. Brand and Cost Considerations

Premium brands (e.g., KTR, R+W) offer precision engineering software and customization but at higher costs.

Domestic alternatives (e.g., Kaitian, Tailong) provide cost-effective solutions for general applications.

Selection Example

Scenario: Centrifugal air compressor (90 kW power, 3000 rpm, axial thermal displacement ±2 mm, non-corrosive ambient).

1. Calculate rated torque: 

T=9550×90/3000≈286.5 NmT=9550×90/3000≈286.5Nm. Apply a 1.5x safety factor (≈430 Nm).

2. Choose a double-diaphragm coupling (compensates radial installation errors) in 304 stainless steel.
3. Match shaft bores: Motor shaft diameter 50 mm (keyway 15×9), compressor shaft 55 mm (shrink disc connection).
4. Verify maximum speed: Coupling rated for 6000 rpm > operating 3000 rpm.

Notes:

- Bolt preload: Use a torque wrench as required by the manufacturer to avoid overload and deformation of the diaphragm.

- Regular inspection: Although it is a maintenance-free design, it is recommended to check the diaphragm cracks or bolt loosening every year.

- Avoid overload: Instantaneous overload may cause plastic deformation of the diaphragm and loss of compensation ability.

Through systematic parameter matching and environmental analysis, diaphragm couplings can significantly improve the reliability of the transmission system and reduce the risk of downtime.

As a leading supplier of diaphragm couplings, Shanghai Ruiji sells directly from the factory. It can not only provide couplings at factory prices, high-quality products and timely after-sales response, but also provide customized solutions according to customer requirements.