A double planetary mixer combines two mixing actions in one vessel. A planetary drive carries the mixing shafts around the tank center while each shaft also rotates on its own axis. This produces a fast, uniform blend even in high-viscosity materials. Hansheng Automation machines mixer shafts, dispersion shafts, and precision drive components to customer drawings when replacement or modification is required.
Working Principle
Planetary Motion Plus Self-Rotation
The drive system moves the mixing shafts around the center of the tank. At the same time, each shaft rotates on its own axis. The two motions overlap, so the blades sweep different paths through the batch on every pass. Material near the wall, near the center, and at different heights is constantly exchanged. This is what separates a double planetary mixer from a single-shaft design.
High Linear Speed
The tip speed of the dispersion shaft can reach 25 m/s. At this speed, dispersion time drops significantly. The resulting slurry has a smaller particle size and better consistency, which helps break up agglomerates. For battery paste in particular, this matters because agglomerates that survive mixing can affect coating quality and cell performance.
Design and Construction Features
Bearing Selection
The bearings are angular contact ball bearings, fully imported SKF units. Compared with conventional deep groove ball bearings, they carry higher radial and axial loads. That higher load capacity allows the machine to run at higher speeds without deformation, which extends both mixing speed range and service life. Under a linear speed of 21 m/s running continuously for 24 hours, total bearing life is over three years.
Zero-to-Zero Assembly
The assembly follows a zero-to-zero fit approach. Core parts are machined to tight tolerances, with the mixing shaft, dispersion shaft, and bore positions held within 30 microns. This supports concentricity and flatness, so the main components assemble with full contact. The result is smoother running: noise at one meter stays below 70 dB(A).
Sealing
Two sets of mechanical seals are used, combined with soft and hard sealing elements. The planetary gearbox uses a fully sealed structure. Bearing positions were redesigned so that bearing limits are distributed more evenly, which reduces wear. The vacuum chamber holds -0.092 or better over 24 hours at no load. This keeps oil and air from entering the mixing zone during operation.
Blade and Tank Clearance
Clearance is set carefully between blade and blade, blade and tank wall, and blade and tank bottom. The mixing blade has a scraping design at the bottom. The tank bore roundness is held to less than 0.2 mm. These details reduce dead zones and help material move through the full mixing volume.
Torque Output
The mixing blades are cast from 316L stainless steel. For tanks above 650 L, special steel is used that can recover from minor deformation, so the blade does not bend under long periods of high torque. Torque output is checked by computer simulation before production. The design suits high-viscosity, high-solid-content lithium-ion battery cathode and anode slurries, including LFP, NCM, high-nickel NCM, lithium manganese oxide, and lithium cobalt oxide. It also handles both dry and wet mixing processes.
Applications
Lithium-Ion Battery Slurry
The main use is mixing cathode and anode slurry for power batteries. High linear speed and strong torque let the mixer handle high solids content without leaving agglomerates. Uniform slurry supports consistent coating weight and stable cell performance.
Other High-Viscosity Materials
The same design suits other high-viscosity pastes, including electronic paste, ceramic slurry, and some pharmaceutical and chemical intermediates. In each case, the combination of planetary motion and high-speed dispersion does the work that a single-shaft mixer cannot do in one pass.
Maintenance and Replacement Parts
Check blade wear, shaft runout, and seal condition on a regular schedule. The vacuum seal should be tested periodically to confirm it still holds pressure. Blade clearance should be measured and recorded so that wear trends are visible over time. When replacement shafts, blades, or sealing components are needed, Hansheng Automation can machine them to drawing, including the tight tolerances the assembly requires.
Our precision custom machining capability is not limited to double planetary mixers. Hansheng Automation also produces parts for filling machinery, food processing equipment, and medical devices, along with precision components for yachts and RC cars. From single parts to small batch runs, we machine to customer drawings and deliver parts for assembly.
