Mitsubishi M80 Built-IN Spindle Motor SJ-2B6908TK

🔧 Mitsubishi SJ-2B6908TK – Description

The SJ-2B6908TK is a Mitsubishi Electric SJ-B Series built-in spindle motor designed for high-torque CNC machining applications. It is a dual-coil (low-speed / high-speed) spindle motor used inside machine tool spindles where high rigidity, heavy cutting capability, and stable torque control are required.

⚙️ Key Description

• Series: SJ-B Built-in Spindle Motor
• Type: Coil changeover (low-speed / high-speed windings)
• Application: CNC machining centers, heavy-duty milling machines, high-load spindle systems
• Drive compatibility: MDS-D2-SP-320 spindle drive unit

⚡ Functional Characteristics

• Operates with two speed ranges:
  • Low-speed coil → very high torque for rough/heavy cutting
  • High-speed coil → finishing and higher spindle speeds
• Designed for high-load stability and rigid machining
• Built for continuous industrial operation with liquid cooling (oil jacket type)

📊 Key Performance Overview

• Power output:
  • Continuous: 15 kW (low-speed coil) / 22 kW (high-speed coil)
  • Short-time (50% ED): 22 kW / 30 kW
• Torque:
  • Continuous: 819 N·m / 467 N·m
  • Short-time: 1200 N·m / 637 N·m
• Speed range:
  • Low-speed coil: ~175 r/min base
  • High-speed coil: ~450 r/min base
  • Maximum speed: 1000 / 3300 r/min

🧩 Mechanical & Construction Details

• Rotor inertia: 1.105 kg·m² (very high → strong cutting stability)
• Motor mass: ~143 kg (stator), ~91 kg (rotor)
• Stator outer diameter: ~Ø369.5 mm
• Rotor inner diameter: ~Ø165 mm
• Cooling requirement: ~9920 W heat dissipation with oil cooling system

🏭 Typical Applications

The SJ-2B6908TK is typically used in:

• Heavy-duty CNC machining centers (large VMCs)
• High-load milling and roughing operations
• Industrial production machines requiring maximum spindle torque
• Applications where low-speed cutting force is more important than high RPM

⚠️ Summary

The SJ-2B6908TK is one of the highest torque models in the SJ-B 6900 series, offering:

• Extremely high torque (up to ~1200 N·m short-time)
• Very high inertia for stable heavy cutting
• Lower maximum speed compared to smaller SJ-B models
• Optimized for rough machining and heavy-duty cutting rather than high-speed finishing