Planetary Sun Gear

Structural characteristics

• Located at the center: In the planetary gear mechanism, the sun gear is located at the center position, and multiple planetary gears are evenly distributed around it and mesh with it.

• Coordination with planetary gears: The sun gear serves as the driving or driven wheel, transmitting power to the planetary carrier or ring gear through meshing with the planetary gears, achieving functions such as deceleration, acceleration, or changing transmission direction.

 

Performance advantages

•High precision: By precisely controlling the mold size and sintering shrinkage rate, gears with extremely small tolerances can be produced to meet the requirements of precision transmission.

• Self lubrication: There is a pore structure inside that can store lubricating oil, which seeps out during operation to form a lubricating film, reducing friction and wear, lowering noise, and extending service life.

•Low cost: The material utilization rate is over 95%, and it is suitable for large-scale production, which can reduce production costs.

 

Application area

•Automotive manufacturing: used for automotive engines, transmissions, etc., such as BYD's "e-platform 3.0" which uses iron-based powder metallurgy planetary gears to achieve 0.005mm dimensional accuracy and reduce costs.

•Industrial robots: can meet the high requirements for precision, stability, and reliability of robot joint motion.

•Household appliances, such as washing machine reducers, utilize their self-lubricating and low-noise characteristics to enhance product performance and user experience.

 

 

Commodity	Factory customized high precision strong wear resistance powder metallurgy planetary sun gear
Raw Material	Fc0208/Fn0208
Size	Customer's Drawing
Density	6.7- 7.4 g/cm3
Technology	Powder Metallurgy - Machining
MOQ	5000 PCS
Feature	High strength, high precision

Usage

Cars, household appliances, electronic products, electric tools, etc

 

 

 

 

 

 

 

 

How to adapt the tooth profile design (such as modulus and pressure angle) of planetary sun gears to powder metallurgy processes?

 

1, Adaptation optimization of modular design
① Moderate modulus range (0.5-2mm)
The forming ability of powder metallurgy molds for fine tooth profiles is limited, and a small modulus (<0.5mm) can easily lead to insufficient filling or a decrease in strength; If it is too large (>2mm), it increases the difficulty of pressing and material waste.
Case: The commonly used module for micro reducer sun gear is 1-1.5mm, balancing the strength of the teeth and the feasibility of the process.
Root fillet optimization
② Avoid sharp corner design, use root fillet with R ≥ 0.2mm to reduce mold stress concentration, improve the success rate of billet demolding and gear fatigue life .

 

2, Process adaptation of pressure angle and tooth profile
① Standard pressure angle (mainly 20 °)
A pressure angle of 20 ° balances transmission efficiency and mold life: a pressure angle that is too small will increase radial force, leading to cracking of the billet during compression; If it is too large, it will increase the sliding friction of the tooth surface.
Alternative solution for helical gears: helical gears (β ≤ 15 °) can be achieved through segmented pressing, but the complexity and cost of the mold need to be evaluated.
② Tooth profile modification technology
Add a shaping amount of 0.01-0.03mm to the tooth top/root to compensate for tooth distortion caused by sintering shrinkage and ensure meshing accuracy.

 

3, Structural Integration and Lightweight Design
① Integrated functional integration
By utilizing the advantages of powder metallurgy in one-time molding, structures such as oil grooves and weight reducing holes are designed synchronously with tooth profiles to reduce post-processing (such as the integration of self-lubricating oil grooves in 1).
Example: The sun gear is integrated with the connecting flange to avoid assembly errors and improve axial load-bearing capacity.
② Thin walled lightweight design
The wall thickness can be reduced to 1-2mm (traditional processes require ≥ 3mm), and rigidity is ensured through material porosity control (density ≥ 7.0g/cm ³).

 

4, Collaborative design of materials and processes

Parameter	Requirements for powder metallurgy adaptation	Comparison of Traditional Processing
Tooth surface accuracy	DIN 8-9 levels (dependent on mold accuracy and shaping process)	DIN 6-7 levels (dependent on cutting)
Surface roughness	Ra ≤ 1.6 μ m (requires surface densification treatment)	Ra ≤ 0.8 μ m (achieved through gear grinding)
Heat treatment	Low temperature carburizing (to avoid deformation)	High frequency quenching (high risk of deformation)

Note: By adjusting the powder alloy composition (such as adding Ni, Cu), the tooth surface hardness (HRC 45-55) can be improved without the need for secondary heat treatment.

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