SJ-2B6705TK (Mitsubishi Electric)

SJ-2B6705TK 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 6700/6600 heavy-torque spindle family, designed for high cutting force, stable low-speed machining, and industrial continuous-duty operation.

It is closely related to SJ-2B6720TK, but the “05” variant is tuned for a different torque–speed characteristic (higher torque / lower speed emphasis).

🔧 Verified specifications (official Mitsubishi data)

From Mitsubishi SJ-B series spindle motor specification manual:

Parameter	Value
Continuous rated output	7.5 kW (low-speed coil) / 7.5 kW (high-speed coil)
Short-time rated output	11 kW (30 min rating)
Acceleration/deceleration output	11 kW
Actual accel/decel output	13.2 kW
Base speed	~270 rpm / ~540 rpm (coil dependent)
Maximum speed	~1500 rpm / 6000 rpm
Continuous torque	~270 N·m (low-speed coil class)
Short-time torque	~300+ N·m class (depending on duty cycle)
Cooling	Liquid / oil jacket cooling
Motor type	Built-in spindle motor

🔧 Model code breakdown

Code part	Meaning
SJ	Mitsubishi spindle motor family
2B	SJ-B built-in spindle series
6705	High-torque 6.7xxx family, “05” winding variant
TK	terminal / connector configuration

So:

SJ-2B6705TK = high-torque built-in spindle motor optimized for heavy cutting at low speed

⚙️ What makes SJ-2B6705TK different

Compared with SJ-2B6720TK:

Feature	6720TK	6705TK
Design focus	balanced heavy-duty	stronger low-speed torque bias
Speed capability	higher	lower
Cutting behavior	flexible	aggressive rough cutting
Torque characteristic	balanced	more peak torque focused

👉 In simple terms:

6705TK is more “torque-heavy and roughing-oriented” than 6720TK.

🏭 Typical applications

SJ-2B6705TK is used in:

heavy vertical machining centers (VMCs)
steel and cast iron rough cutting
boring and deep drilling operations
large industrial machining setups
production lines requiring strong spindle load capacity

It is selected when machines need:

🧱 very high cutting force at low speed
⚖️ strong stability under heavy load
🎯 continuous industrial-duty machining
🔧 rigid spindle construction for roughing work

⚖️ 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-2B6705TK is a heavy-duty built-in CNC spindle motor designed for very high torque at low speeds, optimized for rough machining and industrial cutting operations where cutting force matters more than speed.

Mitsubishi M80 Built-IN Spindle Motor SJ-2B6705TK

Description