Types of Planetary Gearboxes for Automated Equipment and Manufacturing Process

Planetary gearboxes for automated equipment come in various types, including different output shaft configurations (output shaft type, flange type, and right-angle type), gear stages (single-stage and multi-stage), and lubrication methods (oil-immersed and grease-lubricated). Their structure mainly consists of the gear system (sun gear and planet gears), planet carrier, ring gear, and input/output shafts. The manufacturing process involves component machining, heat treatment, surface treatment, and assembly, with strict quality control to ensure high performance and reliability for diverse industrial applications.

Types of Planetary Gearboxes for Automated Equipment

• Classification by Output Shaft Configuration:
  • Output Shaft Type: The planetary gearbox itself has an output shaft, which can be configured coaxially or in parallel with the input shaft. The output shaft can be in the form of a keyed shaft, a smooth shaft, or a spline shaft, and can be fitted with pulleys, gears, sprockets, or other additional drive components. It is widely used in machine tools, lathes, milling machines, water jet cutting machines, and other types of automated equipment.
  • Flange Type: The output side of the gearbox is designed according to the ISO 9409 specification, allowing it to be paired with various small gears, pulleys, or couplings that meet this specification. It provides higher torsional rigidity and is suitable for applications with constantly changing motion directions, such as parallel delta industrial robots and rack-and-pinion drives.
  • Right-Angle Type: It features a 90-degree right-angle gearbox that can redirect the torque and speed from the servo motor by 90 degrees. This design saves installation space and makes the equipment more compact. The output end typically comes in both output shaft and flange types, and it is used in automated machinery, photovoltaic panel handling, automated warehousing systems, and other similar applications.
• Classification by Gear Stages:
  • Single-Stage Planetary Gearbox: It has a simple structure, lower cost, higher transmission efficiency, and is easy to maintain. It is suitable for industries such as packaging machinery and printing equipment where precision requirements are not extremely high.
  • Multi-Stage Planetary Gearbox: It offers a higher reduction ratio and can provide greater torque output with higher precision, but it is more expensive. It is used in precision manufacturing fields such as CNC machine tools and robot joints.
• Classification by Lubrication Method:
  • Oil-Immersed Planetary Gearbox: It uses lubricating oil for lubrication, has better heat dissipation, and can carry higher loads. However, it requires higher sealing performance and regular oil changes. It is suitable for heavy-duty working conditions in industries such as metallurgy and mining.
  • Grease-Lubricated Planetary Gearbox: It uses lubricating grease as the lubricant. It has good sealing performance and a longer maintenance-free period. Its heat dissipation is not as good as the oil-immersed type. It is suitable for light or medium-duty working conditions in industries such as medical devices and food processing.

Structure of Planetary Gearboxes

• Gear System (Sun Gear and Planet Gears): The input gear is the sun gear, which is directly connected to the motor output shaft and serves as the power input end. It has fewer teeth and a smaller diameter, and it drives the planet gears through high-speed rotation. The planet gear set consists of multiple gears evenly distributed around the sun gear. They mesh with both the sun gear and the ring gear, rotating on their own axes while orbiting the sun gear. The speed reduction is achieved through the difference in the number of teeth.
• Planet Carrier (Planet Carrier Assembly): It converts the orbital motion of the planet gears into the rotation of the output shaft, which is the final power output component. Its structure must withstand high torque and is usually made of high-strength alloy. The planet carrier and output shaft are designed as an integrated structure, with the front and rear bearings widely spaced within the housing to form a stable, one-piece structure. This ensures high torsional rigidity and precision. The axial clearance can be adjusted through the adjustment sleeves on the planet carrier.
• Ring Gear: Fixed to the gearbox housing, it restricts the motion trajectory of the planet gears and forms the transmission path for the planetary gears. It has more teeth and a larger diameter, and it must be manufactured with high precision to ensure smooth transmission.
• Input Shaft and Output Shaft: The input shaft directly connects to the motor or power source and transfers high-speed, low-torque power to the sun gear. The output shaft is rigidly connected to the planet carrier and outputs low-speed, high-torque power to the load equipment. It usually has keyways or spline interfaces.

Manufacturing Process of Planetary Gearboxes

• Component Machining: The first step in manufacturing a planetary gearbox is the machining of the various components. Machining processes include casting, forging, turning, grinding, cold extrusion, and hot precision forging. Casting and forging are commonly used for the production of large gears and planet gears to ensure their strength and shape.
• Component Heat Treatment: After machining, the components undergo heat treatment processes, which can be divided into quenching and tempering. Quenching can increase the hardness and toughness of the components, while tempering can reduce the brittleness effect of quenching, thereby maintaining the toughness of the components. This ensures their performance and lifespan during use.
• Surface Treatment: After heat treatment, the components need to undergo surface treatment processes, including gear surface polishing, gear surface nitriding, electroplating, sandblasting, etc. These processes improve the wear resistance and corrosion resistance of the components, thereby enhancing the overall performance and service life of the planetary gearbox.
• Assembly: After the components have been machined and surface-treated, assembly work is carried out. It is crucial to carefully check the fit and clearances of each part. The assembly process requires high attention to detail, as inadequate run-in or improper installation can affect the performance of the planetary gearbox. After assembly, multiple performance tests are conducted, such as noise testing, vibration testing, and efficiency testing, to ensure that the product meets the required performance standards.