WINDSOR, CT – For steel makers, ship builders, OEM’s and job shops machining large, heavy components, reducing part handling and setup time is critical. Moving large workpieces often requires cranes or lifts, and each re-alignment adds significant time—turning what could be a single setup into a process that takes hours or even days.
The Geminis GMi Multiprocess Mill-Turn Lathes were designed and engineered to solve this challenge. By consolidating multiple machining operations — including turning, milling, boring, and grinding — into a single setup on one machine, manufacturers can dramatically cut production time and improve accuracy on parts with tight tolerances.
A Hybrid Machining Solution
The Geminis GMi Series represent a new class of multiprocess lathes, purpose-built for complex, large-scale components. These machines combine the flexibility and endless capacity of floor-type milling-boring machines with the structure and rigidity of a heavy-duty flatbed lathe while integrating C-axis, live tooling, and optional Y- and Z-axis milling capabilities. This hybrid design is ideal for large cylindrical parts — such as rolls, turbine rotors, or rail components — that require heavy-duty turning plus keyways, pockets, drilling, or contour milling.
Massive Capacity & Configurability
The GMi Series features three models, GM5i, GM7i and GM9i, and can handle parts from 51” to 98” (1.3 to 2.5 meters) in diameter and 39” to 945” (1 to 24 meters) between centers, with load capacities from 15 to 150 tons.
A standout feature on GMi lathes is the automatic head changing system, which enables fast, precise transitions between different machining operations. Available heads include:
• Heavy-duty turning spindles for roughing
• Orthogonal milling/turning heads with 1° A- and B-axis indexing
• Horizontal milling heads for high-torque OD work
• Boring heads for long boring bars
• Grinding heads (manual or programmable B-axis) for wheels up to 700 mm diameter
For grinding applications, Geminis also offers specialized cycles for plunge, traverse, and taper grinding. The large-diameter wheels allow grinding up to a shoulder without interference from spindle bearings. Custom boring heads and large-diameter boring bars are also available.
Tooling & Power
For added flexibility, GMi multiprocess lathes can be equipped with automatic tool changers accommodating ISO 50, CAT 50, Capto (C6, C8, C10), and HSK (63, 100) tooling. Capacity ranges from 30 to 120 tools, and all ATCs feature an arm capable of exchanging tools with the spindle in either vertical or horizontal orientation.
The twin-drive headstock offers C-axis positioning to 0.001° with accuracy within ±2 arc seconds. Main spindle power reaches 161 hp with maximum torque of 120,000 Nm. Control options include Siemens, Fanuc, or Fagor CNC systems.
Operator-Centric Design
Geminis emphasizes operator ergonomics and visibility. The machine layout provides a direct line of sight from the operator station to the tool tip during cutting. Optional camera systems and auxiliary monitors further improve safety and efficiency by allowing operators to track tool approach and respond quickly to any issues.
About Geminis Lathes
With more than 65 years of expertise in building flatbed lathes, Geminis has spent the last 15 years advancing its multiprocess platform, focusing on highly configurable solutions tailored to each customer’s unique requirements.
The Geminis GMi Series of Multiprocess Mill-Turn Lathes are a game-changer for manufacturers working with large, complex components. By combining heavy-duty turning power with advanced milling, boring, and grinding capabilities — all in one setup — the GMi lathes reduce downtime, boosts accuracy, and eliminate the need for multiple machines and part transfers.
For industries such as energy, rail, aerospace, and heavy equipment manufacturing, the GMi Series Multiprocess Mill-Turn Lathes deliver unmatched versatility and productivity.