Mitsubishi M80 Built-IN Spindle Motor SJ-2B6709TK

🔧 Mitsubishi SJ-2B6709TK – Description

The SJ-2B6709TK is a Mitsubishi Electric SJ-B Series built-in spindle motor, designed for high-torque CNC spindle applications where strong cutting power and stable performance are required.

It is a dual-coil built-in motor used inside machine tool spindles, enabling a compact structure with high rigidity and efficient power transmission.

⚙️ Key Description

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

⚡ Functional Characteristics

• Operates with two-speed coil system:
  • Low-speed coil → very high torque for rough/heavy cutting
  • High-speed coil → up to finishing and high RPM machining
• Designed for:
  • High cutting load stability
  • Strong torque output at low speed
  • Continuous industrial operation with liquid cooling

📊 Key Performance Overview

• Power output:
  • Continuous: 15 kW (low-speed) / 22 kW (high-speed)
  • Short-time (30 min): 22 kW / 30 kW
• Torque:
  • Continuous: 409 N·m / 210 N·m
  • Short-time: 500 N·m / 286 N·m
• Speed range:
  • Low-speed coil: ~350–1000 r/min
  • High-speed coil: up to 6000 r/min

🧩 Mechanical & Construction Details

• Rotor inertia: ~0.37 kg·m²
• Motor mass: ~83 kg (stator), ~49 kg (rotor)
• Stator outer diameter: ~Ø299.5 mm
• Rotor inner diameter: ~Ø130 mm
• Motor length: ~450 mm

🌡️ Cooling & Operation

• Cooling type: Liquid/oil cooling (stator jacket required)
• Cooling flow: ~15 L/min typical
• Heat dissipation: ~6.18 kW required cooling capacity
• Insulation class: Industrial-grade F-class system (typical SJ-B design)

🏭 Typical Applications

The SJ-2B6709TK is commonly used in:

• Heavy-duty CNC vertical machining centers (VMC)
• High-load milling operations
• Production machines requiring high torque stability
• Industrial machining where tool load varies heavily

⚠️ Summary

Compared to smaller SJ-B models, the SJ-2B6709TK stands out for its higher torque capability (up to 500 N·m short-time), making it better suited for heavier cutting conditions and tougher materials, while still maintaining 6000 rpm high-speed finishing capability.