SJ-BG120C/200-01 (R) (Mitsubishi Electric)

SJ-BG120C/200-01 (R) is a Mitsubishi Electric SJ-BG series built-in AC spindle motor, designed for high-speed precision CNC machining where the motor is integrated directly into the spindle structure.

It belongs to the SJ-BG built-in spindle motor family, optimized for:

• compact spindle construction
• high rotational speed
• low vibration
• precision contour machining
• stable thermal performance

Mitsubishi officially lists this model in the SJ-BG specification manuals.

🔧 Model code breakdown

So:

SJ-BG120C/200-01(R) = 120 mm built-in spindle motor for ~20,000 rpm precision machining applications

🔧 Verified specifications

From Mitsubishi SJ-BG spindle motor manuals:

⚙️ What makes the “120C” version different

Compared with the earlier 120A variant:

The 120C variant generally provides:

• improved rigidity
• larger rotor/stator structure
• better thermal stability
• stronger cutting capability during sustained operation

⚙️ What “(R)” means

The (R) suffix is typically used for:

• revised rotor configuration
• balancing specification update
• OEM/machine-builder customization variant

It is not a separate spindle family, only a configuration revision.

🏭 Typical applications

SJ-BG120C/200-01(R) is commonly used in:

• high-speed machining centers
• mold & die machining
• graphite machining
• precision contour milling
• compact integrated spindle units
• aerospace finishing operations

It is selected when machines need:

• ⚡ high spindle speed (~20k rpm)
• 🎯 high contour accuracy
• 📉 low vibration
• 🧱 improved spindle rigidity

⚖️ Position in Mitsubishi spindle lineup

Official Mitsubishi spindle lineup documentation identifies SJ-BG as the built-in spindle series.

🧠 Simple explanation

SJ-BG120C/200-01(R) is a built-in CNC spindle motor designed for precision high-speed machining up to about 20,000 rpm, offering higher rigidity and stronger continuous cutting capability than smaller BG spindle variants.