Mazak Quick Turn Nexus 450-II
Key Specifications
Max Spindle
Tool Capacity
Spindle Power
Max Turn Length
max turning diameter
swing over bed
Overview
The Mazak Quick Turn Nexus 450-II is a high-performance CNC turning center designed for large-diameter chucking and bar work in production environments. With a 21-inch chuck capacity, 600 mm max turning diameter, and a powerful 37 kW (50 hp) built-in spindle motor, the QTN-450-II targets heavy-duty turning applications in oil and gas, aerospace, and general manufacturing where part diameter and material hardness push conventional machines to their limits.
The machine features a 45-degree slant bed design with a thermally symmetric headstock that minimizes thermal displacement during extended production runs. The NEXUS-II generation updated the casting, spindle bearing preload system, and coolant-through tooling integration over the original QTN-450. Maximum turning diameter is 600 mm (23.62 in) and turning length reaches 1,524 mm (60 in) on the standard bed configuration. Bar capacity through the spindle bore is 102 mm (4 in).
MAZATROL SmoothG CNC runs on a 15-inch full-color touchscreen with both conversational and ISO G-code programming. The 12-position turret with VDI tooling interface provides rigid, repeatable tool clamping. Spindle speed maxes at 2,000 RPM — appropriate for the large-diameter, heavy-material work this machine targets. Rapid traverse is 25 m/min in X and 30 m/min in Z.
The QTN-450-II competes with the Okuma LB4000 EX II, Doosan Puma 480, and Haas ST-45. Against the Haas, the Mazak delivers a more rigid spindle design, superior thermal control, and a more capable conversational control at a higher price point. For shops turning components in the 400–600 mm diameter range regularly, the QTN-450-II is one of the benchmark machines in the class.
Full Specifications
| Parameter | Value |
|---|---|
| Max Turning Diameter | 600 mm (23.62 in) |
| Max Turning Length | 1,524 mm (60 in) |
| Swing Over Bed | 780 mm (30.7 in) |
| Max Spindle Speed | 2,000 RPM |
| Spindle Motor Power | 37 kW (50 hp) at 25% ED; 22 kW (30 hp) continuous |
| Spindle Torque | 2,450 Nm (1,807 ft-lb) at 25% ED |
| Spindle Nose | A2-11 |
| Chuck Size | 533 mm (21 in) |
| Bar Capacity | 102 mm (4 in) |
| Tool Capacity | 12-position turret |
| X Axis Travel | 350 mm (13.78 in) |
| Z Axis Travel | 1,570 mm (61.8 in) |
| Rapid Traverse X | 25 m/min (984 ipm) |
| Rapid Traverse Z | 30 m/min (1,181 ipm) |
| Machine Weight | 12,500 kg (27,558 lb) |
| CNC Control | MAZATROL SmoothG CNC |
Specifications sourced from mazakusa.com — verified 2026-03-28
Strengths & Limitations
Strengths
- 37 kW built-in spindle motor with 2,450 Nm of torque enables aggressive roughing passes on large-diameter steel, stainless, and nickel alloy parts
- 21-inch chuck and 600 mm turning diameter cover a wide range of large-diameter chucking work in one machine
- Thermally symmetric headstock design minimizes thermal drift during long production runs, maintaining dimensional consistency without frequent re-calibration
- MAZATROL SmoothG conversational programming reduces setup time on short-run and complex parts compared to G-code-only controls
- 102 mm bar capacity enables bar feeding of large-diameter material without bar feeder length restrictions
- Rigid 12-position VDI turret provides excellent tool repeatability and supports high-pressure coolant through tooling for deep bore work
Limitations
- 2,000 RPM maximum spindle speed limits surface footage on smaller-diameter features cut with the large chuck — smaller workpieces get better results on a QTN-250 or QTN-350
- At 12,500 kg, the machine demands a reinforced concrete foundation and careful floor load planning during facility preparation
- Higher price point than the Haas ST-45 or Doosan Puma 480 requires justification in cycle time savings or material capability
- No Y-axis option on the standard 450-II limits milling to on-centerline work; shops needing off-center milling must step up to the QTN-450-MY configuration
Best For
Frequently Asked Questions
01
New pricing for the QTN-450-II typically ranges from $280,000 to $420,000 depending on bed length, tooling configuration, and optional accessories such as high-pressure coolant, chip conveyor, and bar feeder interface. Used machines from 2015–2022 appear on the secondary market in the $120,000–$220,000 range.
02
The -II generation introduced updated casting geometry for improved thermal stability, a revised spindle bearing preload system for longer bearing life, enhanced MAZATROL SmoothG control software, and factory-standard high-pressure coolant preparation. The spindle power and torque specifications remain similar, but the -II delivers better thermal compensation and updated diagnostics.
03
The standard QTN-450-II is a pure turning center without live tooling. For milling capability, Mazak offers the QTN-450-MY variant with live tooling, C-axis, and Y-axis. If a shop needs both heavy turning and milling in one setup on large parts, the QTN-450-MY is the appropriate model.
04
The spindle bore accommodates bar stock up to 102 mm (4 inches) in diameter. For larger bar work, the machine's chuck and tailstock combination handles shafts and longer workpieces supported between centers.
05
Both machines target the same large-diameter turning segment. The Okuma offers its Thermo-Friendly Concept thermal management and OSP-P control, while the Mazak uses a thermally symmetric headstock with MAZATROL SmoothG. The Mazak's conversational programming is broadly considered more intuitive for operators new to the machine. Pricing and cycle time are closely matched; the choice often comes down to existing brand relationships and control preference.
Videos
Mazak North America
BFG Machine Tools Inc
Mazak North America
MachineryNetwork
Community Discussions
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Links to community discussions. Summaries are editorial — visit the original thread for full context.
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