Why Do 45MM Tubular Motors Generate Less Noise Than 35MM Models?

In applications such as smart home systems, medical equipment, and high-end office environments, noise reduction is a critical performance metric for tubular motors. A notable trend in the industry is the quieter operation of 45mm tubular motors compared to their 35mm counterparts. This phenomenon is not accidental but rooted in precise engineering design and material science. 
1. Structural Advantages: Larger Diameter, Reduced Vibration
The 45mm tubular motor’s increased diameter directly translates to a larger internal space. This allows for a more robust stator and rotor design. In 35mm models, the compact structure limits the size of magnetic components, leading to higher magnetic saturation during operation. Magnetic saturation exacerbates harmonic vibrations, which are a primary source of high-frequency noise.
In contrast, the 45mm motor’s expanded geometry enables optimized winding distribution and reduced air gap flux density. These improvements minimize electromagnetic vibration, resulting in smoother rotation and noise levels often 3-5 dB lower than 35mm motors under equivalent loads.
2. Magnetic Circuit Optimization: Precision in Flux Distribution
The magnetic circuit design is a core factor influencing motor noise. Smaller motors (e.g., 35mm) often face challenges in achieving uniform magnetic flux distribution due to spatial constraints. Uneven flux induces eddy current losses and torque ripple, generating audible "humming" noises.
45mm motors utilize advanced magnetic circuit simulations to optimize the placement of permanent magnets and laminations. For example, some manufacturers employ Halbach array configurations to concentrate magnetic flux on the working air gap, reducing stray fields. This refined design lowers cogging torque fluctuations by up to 20%, significantly suppressing vibration-induced noise.
3. Bearing and Transmission System Upgrades
Noise in tubular motors isn’t solely electromagnetic; mechanical friction and gear engagement also play significant roles. 35mm motors often use smaller bearings and compact planetary gear sets, which operate at higher rotational speeds to achieve the same torque output. Smaller bearings inherently have lower load capacities, leading to faster wear and increased friction noise over time.
The 45mm models benefit from larger, precision-grade bearings (e.g., P5 or P4 class) with advanced lubrication systems. Additionally, their gearboxes incorporate helical gears or harmonic drive mechanisms, which reduce contact stress by 30-40% compared to the spur gears commonly found in 35mm motors. This results in quieter, more durable transmission.
4. Thermal Management and Noise Correlation
Heat dissipation efficiency indirectly impacts motor noise. Compact 35mm motors generate concentrated heat during continuous operation, causing thermal expansion of components. This expansion alters tolerances between moving parts, increasing friction and noise.
The 45mm design integrates enhanced thermal management, such as aluminum alloy housings with heat-dissipating fins and thermally conductive potting materials. By maintaining stable operating temperatures, these motors avoid thermal deformation and ensure consistent gap tolerances, contributing to long-term quiet operation.
5. Manufacturing Precision: From Tolerance Control to Material Selection
Higher-end 45mm tubular motors often adopt CNC-machined components and high-precision assembly processes. For instance, rotor concentricity is controlled within 5μm (compared to 10–15μm in economy 35mm models), minimizing unbalanced centrifugal forces.
Material choices also matter. Noise-damping composites, such as polyamide-impregnated gears or rubber-isolated mounts, are more frequently used in 45mm motors to absorb vibrations. In contrast, cost-driven 35mm models may prioritize rigid plastics or standard steels, which transmit noise more effectively.