SJ-2B6720TK (Mitsubishi Electric)

SJ-2B6720TK is a Mitsubishi Electric SJ-B series built-in AC spindle motor, used in medium-to-heavy duty CNC machining centers. It belongs to the SJ-2B 6700/6720 family, which is one of the more powerful configurations in the SJ-2B lineup, designed for high torque, stable cutting, and industrial heavy machining.

🔧 Verified specifications (official Mitsubishi data)

From Mitsubishi SJ-B series specification manual:

Parameter	Value
Continuous rated output	15 kW (low-speed coil) / 22 kW (high-speed coil)
Short-time rated output	22 kW / 30 kW
Acceleration/deceleration output	22 kW / 26 kW
Actual accel/decel output	26.4 kW / 36 kW
Base speed	700 rpm / 1600 rpm (coil dependent)
Maximum speed	1500 rpm / 10,000 rpm
Continuous torque	205 N·m / 136 N·m
Short-time torque	300 N·m / 160 N·m
Rotor inertia	0.20 kg·m²
Stator OD	~299.5 mm class
Rotor inertia class (GD²)	0.80 kg·m²
Cooling	Liquid / oil jacket cooling
Mass	~45 kg stator / ~26 kg rotor

🔧 Model code breakdown

Code part	Meaning
SJ	Mitsubishi spindle motor family
2B	SJ-B built-in spindle series
6720	15–22 kW class, high-torque winding configuration
TK	terminal / connector type

So:

SJ-2B6720TK = high-torque built-in spindle motor for heavy CNC machining (15–22 kW class)

⚙️ What makes SJ-2B6720TK important

This model is one of the stronger SJ-2B spindles, and compared to smaller 4500-series motors:

⚡ Much higher torque capability (up to ~300 N·m short-time)
🧱 Designed for heavy cutting loads
🎯 Stable low-speed machining performance
🔧 Industrial-grade continuous operation

It sits in the category of “heavy-duty built-in spindle motors” in Mitsubishi’s older architecture.

🏭 Typical applications

SJ-2B6720TK is used in:

vertical machining centers (VMCs)
heavy milling machines
steel and cast iron machining
boring and drilling operations
industrial CNC production lines

It is chosen when machines require:

🧱 high cutting force capability
⚖️ strong low-speed torque stability
🎯 continuous heavy-duty machining
🔧 rigid spindle structure for industrial use

⚖️ Position in Mitsubishi spindle lineup

Series	Role
SJ-2B	compact built-in spindle motors (older generation)
SJ-BG	modern high-speed built-in spindles
SJ-DG	high-torque cutting spindles
SJ-DL	external high-speed spindle motors

🧠 Simple explanation

SJ-2B6720TK is a 15–22 kW class built-in CNC spindle motor designed for heavy-duty machining, offering high torque, strong cutting ability, and stable industrial performance under load.

Mitsubishi M80 Built-IN Spindle Motor SJ-2B6720TK

Description