Mitsubishi M80 Built-IN Spindle Motor SJ-2B6906TK

🔧 Mitsubishi SJ-2B6906TK – Description

The SJ-2B6906TK is a Mitsubishi Electric SJ-B Series built-in spindle motor used in CNC machine tools for high-torque, heavy-duty spindle applications. It is designed for integrated spindle construction, where the motor is built directly into the machine spindle for maximum rigidity and precision.

⚙️ Key Description

• Series: SJ-B Built-in Spindle Motor
• Type: Dual-coil spindle motor (low-speed / high-speed winding)
• Application: CNC machining centers, heavy milling machines, high-load cutting operations
• Drive unit compatibility: MDS-D2-SP-400 spindle drive unit

⚡ Functional Characteristics

• Operates using coil changeover system:
  • Low-speed coil → very high torque for rough/heavy cutting
  • High-speed coil → finishing and higher spindle RPM
• Designed for:
  • High cutting force stability
  • Continuous industrial operation
  • Heavy-duty machining with large tools

📊 Key Performance Overview

• Power output:
  • Continuous: 15 kW (low-speed coil) / 30 kW (high-speed coil)
  • Short-time (30 min): 22 kW / 37 kW
• Acceleration / deceleration output:
  • Standard: 22 kW / 37 kW
  • Peak: 26.4 kW / 44.4 kW
• Torque:
  • Continuous: 819 N·m (low-speed) / 477 N·m (high-speed)
  • Short-time: 1200 N·m / 589 N·m
• Speed range:
  • Low-speed coil: ~175–1000 r/min
  • High-speed coil: up to 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 diameter: ~Ø369.5 mm
• Rotor inner diameter: ~Ø165 mm
• Motor length: ~555 mm
• Cooling: Liquid/oil cooling required (high heat load ~9.8 kW)

🏭 Typical Applications

The SJ-2B6906TK is commonly used in:

• Heavy-duty CNC vertical machining centers (large VMCs)
• High-load rough machining operations
• Deep cutting / large tool diameter milling
• Industrial production where maximum torque is more important than high speed

⚠️ Summary

The SJ-2B6906TK is a high-torque industrial spindle motor in the SJ-B 6900 series, characterized by:

• • Very high torque (up to ~1200 N·m short-time)
  • High inertia for stable heavy cutting
  • Lower maximum speed compared to smaller models
  • Designed primarily for roughing and heavy machining operations