Mitsubishi M80 High-output Specifications Motor SJ-DG3.7/120-03T

SJ-DG3.7/120-03 is a Mitsubishi Electric SJ-DG series built-in spindle motor used in high-speed CNC machine tool spindles.

Unlike standard SJ-D motors, the SJ-DG series is a built-in spindle type, meaning the motor stator is integrated directly into the machine spindle structure.

🔧 Key specifications (SJ-DG3.7/120-03)

⚙️ What makes SJ-DG different

Standard SJ-D

• Separate spindle motor
• Connected by belt or coupling
• External housing

SJ-DG

• Motor built directly into spindle assembly
• Rotor integrated with spindle shaft
• Higher rigidity
• Lower vibration
• Better high-speed performance

🧠 Code breakdown

• SJ-DG → built-in spindle motor series
• 3.7 → rated power (3.7 kW)
• /120 → frame / spindle size class
• -03 → mechanical/electrical revision

⚙️ Typical applications

Used in:

• high-speed machining centers
• precision mold machining
• compact CNC spindle systems
• high-rpm finishing operations

Especially useful where:

• vibration reduction matters
• thermal stability matters
• spindle compactness is important

📐 Typical characteristics

• Integrated spindle rotor structure
• Very high rotational accuracy
• Lower mechanical transmission loss
• Better dynamic response than belt systems
• High-speed balanced construction

⚠️ Important notes

• Requires dedicated spindle cooling system
• Not interchangeable with standard SJ-D motors
• Usually serviced as part of spindle assembly
• Requires Mitsubishi spindle drive system

🧠 Simple explanation

SJ-DG3.7/120-03 is a 3.7 kW built-in CNC spindle motor integrated directly into the spindle for high-speed, low-vibration machining.