Chiron 831 MT

$650,000 - $950,000 Updated 2025-03-15

Key Specifications

Max Workpiece ⌀

400 mm (15.7 in)

axes

5-axis simultaneous mill-turn

spindle configuration

Separate turning and milling spindles

machining type

Complete machining (mill-turn from bar or chuck)

machine design

STAMA heritage, rigid column architecture

machine bed

Cast iron

Overview

The Chiron 831 MT is a heavy-duty 5-axis mill-turn machining center from the STAMA heritage line, designed for complete machining of complex workpieces with diameters up to 400 mm. It is the largest single-spindle mill-turn platform in the Chiron Group portfolio, positioned for aerospace, energy, and heavy industrial applications where parts demand both aggressive turning and complex 5-axis milling in one clamping.

Like the smaller 715 MT, the 831 MT features separate turning and milling spindles — a design philosophy inherited from STAMA that avoids the compromises of single-spindle mill-turn machines. The larger work envelope and higher stiffness accommodate heavier cuts, thicker materials, and bigger parts than the 715 MT. The machine handles chuck parts and bar stock, with the 400 mm diameter capacity opening the door to larger flanges, housings, manifolds, and structural components that require combined operations.

The integrated tool store provides extensive capacity for complex parts requiring dozens of milling and turning tools. The rigid column architecture with cast-iron bed delivers the stiffness needed for heavy turning and milling forces on steel, titanium, and Inconel. The 5-axis simultaneous capability allows machining of complex contours, cross-holes, and angular features that would require multiple setups on separate machines. The control is Siemens SINUMERIK 840D sl.

New 831 MT machines price between $650,000 and $950,000 depending on spindle configuration, tool magazine size, automation, and workholding options. The machine competes with the DMG Mori NTX 3000, Mazak Integrex i-400, and Okuma MULTUS B400. Its advantage is the STAMA-heritage complete machining approach with separate spindles optimized for their respective operations. Used 831 MT units from 2016-2022 trade between $350,000 and $650,000.

Full Specifications

Parameter	Value
Max Workpiece Diameter	400 mm (15.7 in)
Axes	5-axis simultaneous mill-turn
Spindle Configuration	Separate turning and milling spindles
Machining Type	Complete machining (mill-turn from bar or chuck)
Machine Design	STAMA heritage, rigid column architecture
Machine Bed	Cast iron
CNC Control	Siemens SINUMERIK 840D sl
Bar Stock	Bar stock and chuck work capable

Specifications sourced from chiron-group.com — verified 2026-03-28

Strengths & Limitations

Strengths

400 mm workpiece diameter capacity handles larger flanges, housings, and structural components than the 715 MT
Separate turning and milling spindles provide optimized performance for each operation without compromise
Complete machining from bar or chuck eliminates re-clamping errors and reduces production lead time for complex parts
Rigid column architecture with cast-iron bed delivers stiffness for heavy turning and milling forces on titanium and Inconel
5-axis simultaneous capability handles complex geometries including cross-holes, angular features, and contoured surfaces
STAMA heritage brings proven complete machining expertise for heavy-duty industrial applications

Limitations

Starting price around $650,000 is significant and competes with established large mill-turn platforms from DMG Mori and Mazak
STAMA brand integration into Chiron Group creates potential uncertainty around long-term parts and service continuity
Cast-iron bed does not offer the vibration damping advantages of Chiron's mineral-cast technology used on milling-only platforms
Machine weight and footprint require substantial factory infrastructure planning
Complex mill-turn programming demands specialized CAM software and experienced programmers with both milling and turning expertise

Best For

Aerospace manufacturers producing landing gear components, turbine housings, and structural parts requiring heavy turning and 5-axis milling Energy sector companies machining valve bodies, pump housings, and turbine components from steel and Inconel Oil and gas manufacturers producing downhole tools, drill collars, and flow control components requiring complete machining Heavy equipment manufacturers machining hydraulic manifolds, cylinders, and structural components up to 400 mm diameter Defense contractors producing munition components, guidance housings, and structural parts requiring combined operations General precision engineering shops seeking to consolidate large-part milling and turning into a single high-capability machine

Frequently Asked Questions

01 What does a new Chiron 831 MT cost?

New 831 MT machines start around $650,000 and can reach $950,000 depending on spindle options, tool magazine capacity, automation, and workholding configuration. Used units from 2016-2022 trade between $350,000 and $650,000.

02 How does the 831 MT compare to the 715 MT?

The 831 MT handles larger parts (400 mm vs 300 mm diameter) with a stiffer, heavier platform designed for more aggressive cutting. The 715 MT handles longer parts (up to 1,000 mm) and has larger standard tool capacity (176 tools). Choose the 831 MT for larger-diameter, heavier-duty work; the 715 MT for longer shaft-type parts.

03 How does the 831 MT compare to the DMG Mori NTX 3000?

The NTX 3000 is a lathe-first mill-turn with superior heavy turning capability and DMG Mori's extensive global service network. The 831 MT has separate turning and milling spindles optimized for each function and the STAMA complete machining heritage. The NTX 3000 has a larger installed base. Choose based on whether turning (NTX) or balanced mill-turn with optimized spindles (831 MT) better fits your parts.

04 Is the 831 MT available as a twin-spindle machine?

Yes. The 831 MT Twin is the dual-spindle variant that machines two identical parts simultaneously for high-volume production. The single-spindle 831 MT provides more flexibility for job shop and mixed-part work.

05 What is the advantage of separate turning and milling spindles?

In single-spindle mill-turn machines, the spindle must compromise between turning and milling requirements. Separate spindles allow each to be optimized — the turning spindle for torque, rigidity, and concentricity; the milling spindle for speed, dynamics, and 5-axis positioning. This results in better performance in both operations compared to a compromise single spindle.

06 Can the 831 MT handle Inconel and titanium?

Yes. The rigid column architecture and cast-iron bed provide the stiffness needed for high cutting forces on Inconel, titanium, and other difficult-to-machine alloys. The machine is specifically positioned for aerospace and energy applications where these materials are common.