SJ-BG090B/300-03☐ (Mitsubishi Electric)

SJ-BG090B/300-03☐ is a Mitsubishi Electric SJ-BG series built-in AC spindle motor, designed for ultra-high-speed precision machining applications where the motor is integrated directly into the spindle.

It is part of the BG built-in spindle family, commonly used in:

high-speed machining centers
PCB drilling machines
mold & die machining
graphite machining
precision grinding spindles

🔧 Model code breakdown

Code section	Meaning
SJ	Mitsubishi spindle motor family
BG	Built-in spindle motor series
090B	90 mm class frame / B-variant structure
300	30,000 rpm class
03	design / winding variant
☐	optional OEM configuration suffix

So:

SJ-BG090B/300-03☐ = 90 mm built-in spindle motor designed for ~30,000 rpm precision machining

🔧 Typical specifications (BG090B/300 class)

Based on Mitsubishi SJ-BG spindle family characteristics: (mitsubishielectric.com)

Parameter	Typical Value
Series	SJ-BG
Motor type	Built-in AC spindle motor
Speed class	30,000 rpm
Cooling	Liquid/oil jacket cooling
Structure	Integrated spindle motor
Application focus	High-speed precision cutting
Bearing system	Precision high-speed bearings
Design focus	Compactness + low vibration

⚙️ What “090B” means

Within the BG family:

Variant	General meaning
090A	standard compact rotor design
090B	revised/high-performance structural variant

The B variant generally indicates:

improved spindle rigidity
optimized thermal behavior
better high-speed balance characteristics

⚙️ What “☐” means

The square placeholder:

☐ = optional manufacturer/OEM specification code

It may represent:

encoder option
bearing specification
cooling configuration
connector orientation
balancing grade
custom machine-builder option

🏭 Typical applications

SJ-BG090B/300-03☐ is used in:

high-speed mold machining
graphite electrode machining
PCB drilling
compact precision machining centers
fine surface finishing operations

It is selected when machines need:

⚡ extremely high spindle speed
🎯 precision contour machining
📉 low vibration
🧱 compact integrated spindle construction

⚖️ Position in Mitsubishi spindle lineup

Series	Role
SJ-V	General machining spindle motors
SJ-VL	Low-inertia tapping/drilling
SJ-DG	High-torque cutting
SJ-DL	Ultra high-speed external spindle
SJ-BG	Built-in ultra-high-speed spindle

🧠 Simple explanation

SJ-BG090B/300-03☐ is a compact built-in spindle motor for ultra-high-speed precision machining around the 30,000 rpm class, optimized for accuracy, rigidity, and low vibration.

Mitsubishi M80 Built-IN Spindle Motor SJ-BG090B/300-03☐

Description