Mitsubishi M80 Built-IN Spindle Motor SJ-2B6905TK

🔧 Mitsubishi SJ-2B6905TK – Description (SJ-B Series Built-in Spindle Motor)

The SJ-2B6905TK is a high-capacity built-in spindle motor from Mitsubishi Electric’s SJ-B series, designed for CNC machine tools that require a balance of high torque, compact size, and efficient dual-speed operation.

It is a coil-changeover spindle motor used inside the machine spindle for rigid, high-performance machining.

⚙️ Key Description

• Series: SJ-B Built-in Spindle Motor
• Type: Dual winding (low-speed / high-speed coil)
• Application: CNC machining centers, milling machines, heavy-duty metal cutting
• Drive compatibility: MDS-D2-SP-320 spindle drive unit

⚡ Functional Characteristics

• Operates with two selectable coils:
  • Low-speed coil → high torque for rough/heavy cutting
  • High-speed coil → finishing / higher RPM machining
• Designed for:
  • Stable torque under heavy load
  • Continuous industrial operation
  • High rigidity spindle integration

📊 Key Performance Overview

• Power output:
  • Continuous: 22 kW (low-speed & high-speed coil)
  • Short-time rating: 26 kW (30 min)
• Acceleration / deceleration output:
  • Standard: 26 kW
  • Actual peak: 31.2 kW
• Torque:
  • Continuous: 500 N·m (low-speed coil) / 210 N·m (high-speed coil)
  • Short-time: 591 N·m / 248 N·m
• Speed range:
  • Low-speed coil: ~420 r/min base
  • High-speed coil: up to 4000 r/min max

🧩 Mechanical & Construction Details

• Rotor inertia: ~0.853 kg·m²
• Motor mass: ~110 kg (stator), ~70 kg (rotor)
• Stator outer diameter: ~Ø369.5 mm
• Rotor inner diameter: ~Ø165 mm
• Motor length: ~465 mm

🌡️ Cooling & Operation

• Cooling type: Liquid / oil cooling (stator jacket required)
• Cooling flow: ~10 L/min
• Required cooling capacity: ~4040 W
• Insulation: Industrial F-class system (typical SJ-B design)

🏭 Typical Applications

The SJ-2B6905TK is commonly used in:

• CNC vertical machining centers (VMC)
• Heavy-duty milling machines
• Production machining requiring high torque at moderate speed
• Industrial cutting operations with varying load conditions

⚠️ Summary

The SJ-2B6905TK sits in the medium–high torque class of SJ-B spindle motors, offering:

• Strong torque (up to ~590 N·m short-time)
• Lower max speed (~4000 rpm) compared to smaller SJ-B models
• Higher mechanical inertia → better stability for heavy cutting