How Do You Properly Attach Magnets and Bearings in a BLDC Motor Rotor Design?

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SUMMARY

The discussion focuses on the proper attachment methods for magnets and bearings in a Brushless DC (BLDC) motor rotor design. Participants confirm that magnets are typically glued to the rotor, often using high-temperature epoxy to ensure durability under operational conditions. The inner ring, resembling a bearing, is generally a metal cylinder that is shrink-fitted into the electrical steel rotor, allowing for an interference fit with the shaft. Additionally, some users suggest that advanced designs may incorporate carbon fiber wrapping for added magnet retention at high RPMs.

PREREQUISITES
  • Understanding of BLDC motor design principles
  • Knowledge of adhesive properties, particularly high-temperature epoxy
  • Familiarity with interference fit and shrink fit techniques
  • Basic machining skills for rotor and shaft fabrication
NEXT STEPS
  • Research the properties and applications of high-temperature epoxy adhesives
  • Learn about interference fit and shrink fit methods in mechanical design
  • Explore advanced rotor designs, including carbon fiber reinforcement techniques
  • Investigate machining processes for creating integrated rotor and shaft components
USEFUL FOR

Engineers, hobbyists, and students involved in motor design, particularly those focused on BLDC motors and mechanical assembly techniques.

fahraynk
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1477087980140-513699624.jpg
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Trying to design a motor for a learning project. Finished the math but having a lot of trouble with design questions. Can anyone give me some insight.

For the rotor in this picture there is a ring magnet. Is the magnet glued on? I think it is glued onto electrical steel.
2nd question, on the inside of the rotor there is a ring that looks like a bearing or something. How does this attach to a shaft? Can you tell me if I am correct... is it just a cylinder of metal shrink fit into electrical steel? and would a shaft just be interfearance fit inside of the rotor... by hammering the shaft in or something?

https://www.google.com/search?q=bldc+rotor&client=tablet-android-lenovo&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiNmsr_8uzPAhWGOyYKHfv5BOoQ_AUICCgC&biw=1280&bih=800#imgdii=uJyn9-Fgwek-4M%3A%3BzN64iZalN3DUgM%3A%3BzN64iZalN3DUgM%3A&imgrc=zN64iZalN3DUgM%3A

Also, does anyone know an online resource where I can learn how these things are done the right way?
 
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I've seen motors where the magnets are glued to the rotor. You need to use the right adhesive - epoxy can loose strength when hot. Have seen high rpm motors with the rotor wrapped in carbon fibre to help retain the magnets but that's not always necessary.

Can you machine the shaft and rotor out of one lump of metal?
 
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