Okuma LB4000 EX II

$220,000 – $290,000 Updated 2026-03-17

Key Specifications

Max Swing Over Bed

800 mm (31.5 in)

Max Turning Diameter

430 mm (16.9 in)

Max Turning Length

1,520 mm (59.8 in)

Chuck Size

315 mm (12 in)

Spindle Speed

20 – 2,500 rpm

Spindle Motor

22 / 26 kW (30 / 35 HP)

Overview

The Okuma LB4000 EX II is a large-bore CNC turning center designed for heavy-duty turning of larger diameter workpieces. Built on the same foundation as the acclaimed LB EX II series, this machine incorporates Okuma's Thermo-Friendly Concept and advanced thermal compensation to maintain dimensional accuracy throughout extended production runs.

With a maximum turning diameter of over 430 mm and a generous swing over bed, the LB4000 EX II handles large flanges, pipe fittings, valves, and other substantial components that exceed the capacity of smaller turning centers. The machine's robust box-way construction and high-torque spindle provide the stability required for aggressive material removal on tough alloys.

The OSP-P300S CNC control delivers a familiar, user-friendly environment with conversational programming, tool life management, and collision avoidance built in. Okuma's Machining Navi technology monitors cutting conditions in real time and adjusts spindle speed to eliminate chatter, extending tool life and improving surface quality.

The LB4000 EX II is a trusted workhorse in oil and gas, heavy equipment, power generation, and aerospace sectors where large, precise turned parts are produced in moderate to high volumes.

Full Specifications

Parameter	Value
Max Swing Over Bed	800 mm (31.5 in)
Max Turning Diameter	430 mm (16.9 in)
Max Turning Length	1,520 mm (59.8 in)
Chuck Size	315 mm (12 in)
Spindle Speed	20 – 2,500 rpm
Spindle Motor	22 / 26 kW (30 / 35 HP)
Max Spindle Torque	3,500 Nm
Bar Capacity	105 mm (4.13 in)
Number Of Tool Stations	12
Rapid Traverse (X/Z)	15 / 20 m/min
Tailstock	Programmable hydraulic tailstock
CNC Control	Okuma OSP-P300S
Machine Weight	Approx. 10,000 kg (22,050 lb)
Floor Space (W X D)	3,750 x 2,150 mm

Strengths & Limitations

Strengths

Large 430 mm turning diameter and 105 mm bar capacity handle substantial workpieces
High-torque spindle excels at heavy roughing cuts in steel, stainless, and exotic alloys
Thermo-Friendly Concept maintains accuracy across long production runs without warm-up
OSP-P300S control simplifies programming with conversational and EIA/ISO G-code modes
Proven LB EX II platform with a strong global support and parts network

Limitations

Lower maximum spindle speed (2,500 rpm) limits suitability for small-diameter high-speed finishing
Heavy machine weight requires reinforced flooring and careful site preparation
No Y-axis standard — off-center milling requires a separate machine or the M variant

Best For

Oil and gas companies turning large valve bodies, flanges, and pipe couplings Power generation suppliers machining turbine shafts, housings, and impellers Heavy equipment manufacturers producing large structural turned components Job shops specializing in large-diameter precision turning for energy and industrial sectors

Frequently Asked Questions

01 What is the maximum turning length of the LB4000 EX II?

The LB4000 EX II offers a maximum turning length of 1,520 mm (59.8 in) in the standard configuration, suitable for long shafts and similar elongated components.

02 Can the LB4000 EX II be equipped with live tooling?

Yes. Okuma offers an LB4000 EX II M variant with a driven tool turret for milling, drilling, and tapping operations. The standard EX II is a turning-only configuration.

03 What chuck size is standard on the LB4000 EX II?

The machine comes standard with a 315 mm (12 in) chuck, appropriate for the large workpiece diameters this machine is designed to handle.

04 How does Machining Navi work on the LB4000 EX II?

Machining Navi monitors acoustic vibration during cutting and automatically adjusts the spindle speed within a defined range to suppress chatter resonance, improving surface finish and extending insert life without operator intervention.

05 Is the LB4000 EX II suitable for automation integration?

Yes. The machine supports gantry robot, bar feeder, and conveyor integrations. The OSP-P300S control includes THINC open architecture for seamless communication with automation controllers and MES systems.