Haas ST Series Turning Centers: Models, Variants and Specs

The Haas ST Series is the high-performance turning center family from Haas Automation, the US machine tool builder. It is Haas's core line of CNC turning centers (two-axis turning lathes at the base, full turn-mill machines in the Y-axis versions), and it spans ten core sizes from the compact ST-10 to the big-bore ST-55. This profile is based on AssetBase data.

Across the family, the size number tracks capacity. The ST-10 runs a 152 mm (6 in) chuck and spins to 6000 rpm for small bar work, while the ST-45 takes a 457 mm (18 in) chuck and the ST-55 is a big-bore oilfield machine with front and rear A1-20 spindle noses. A single "ST" badge therefore covers very different machines, so reading the size number, the variant suffix and the chuck size is the practical way to identify what a given machine actually is.

In the wider machine tool taxonomy, the ST Series sits in the metalworking turning center segment, next to Haas's dual-spindle DS lathes, CL chucker lathes and toolroom lathes, and its milling machines. The values below are based on official OEM datasheets and sources.

The main takeaway: the ST Series is one family but ten size classes, separated first by chuck and bar capacity and then by the variant suffix.

Haas ST Series models covered

The ST Series is organised by a size number that rises with chuck size, bar capacity and spindle torque. The smaller numbers are compact, high-rpm machines built for bar and small chuck work; the middle numbers are general production turning centers; and the larger numbers are heavy machines for big components, with the ST-55 set apart as a big-bore oilfield machine. The capacity figures below come from official OEM datasheets and sources.

The main takeaway: pick the size class by chuck and bar capacity first, then choose the exact size and variant within it.

What the Haas ST Series is used for

In practice, an ST turning center makes round parts. The workpiece rotates in the chuck while a single-point tool on the turret removes material to produce shafts, bushings, flanges, fittings and similar cylindrical components. Work is fed either as bar stock through the spindle bore or as individual blanks held in the chuck, which is why both chuck size and bar capacity matter when matching a machine to a job.

The compact ST-10, ST-15 and ST-20 suit small, high-volume turned parts and bar work, where high spindle speed and a small footprint help. The mid-size ST-25, ST-28 and ST-30 cover everyday production turning across a broad mix of materials, and the large-frame ST-35, ST-40 and ST-45 handle bigger, heavier and longer components where swing and torque matter more than speed.

The Y-axis versions extend the family beyond turning. By adding Y-axis travel, full C-axis positioning and live tooling on a BMT-style turret, they perform off-centre milling, drilling and tapping in the same setup, which turns a lathe into a done-in-one turn-mill machine. The ST-55 is the specialist of the family, built with front and rear A1-20 spindle noses and an extra-large bore for long pipe and oilfield work.

Variants and configurations explained

Within each size, the suffix in a model name signals a real change in the machine rather than a trim level. Bed-length suffixes change how long a part can be. The Y suffix adds a milling axis and live tooling. The S suffix denotes a shorter bed on the large machines, and the EU suffix marks a preconfigured build sold only in Europe. For a buyer or production planner, these suffixes decide part length, whether secondary milling is possible on the machine, and the machine footprint.

The main operational difference: bed suffixes decide part length and footprint, while the Y suffix decides whether the machine can mill as well as turn. As a guide, the Y-axis stroke is modest, for example ±51 mm on the ST-10Y.

Key specification signals

For comparing machines across the ST Series, the most useful signals are chuck size, maximum turning diameter, spindle nose and speed, and spindle power. Chuck and turning diameter set the part size, the spindle nose sets the mounting standard and rigidity, spindle speed suits the machine to small or large diameters, and spindle power indicates how heavy a cut it can sustain. As the size number rises, power and rigidity increase while top speed falls.

The numbers below are class-level ranges based on official OEM datasheets and sources. Within each class the exact figure depends on the specific size and configuration, so read the ranges as comparison signals rather than single fixed values.

The practical takeaway: power and turning diameter climb with the size number while top speed drops, so compare machines within a size class rather than across the whole family. Maximum cutting length follows the same pattern, from about 406 mm on the ST-10 up to 826 mm on mid-size beds, 1118 mm on the ST-40 and ST-45, and 2032 mm on the ST-55, with long-bed (L) variants extending these further. A more detailed technical profile is available in AssetBase.

Energy use and lifecycle CO₂ context

Energy data for turning centers is mostly electrical, and the clearest signal in the datasheets is installed spindle power, which ranges from 11.2 kW on the ST-10 to 41 kW on the largest machines. Servo axes, the hydraulic or pneumatic chuck, coolant pumps and chip conveyors add to the total. Actual consumption is not a fixed figure: it depends on how hard the machine cuts, the material, cycle time, idle periods and how much auxiliary equipment runs, so installed power should be read as a capacity signal rather than a running rate.

It is useful to keep operational energy separate from full lifecycle CO₂. A machine's running energy is only one part of its footprint. Production of the machine, transport, tooling and consumables, maintenance and end-of-life treatment all add separate assumptions, and the electricity mix used on site strongly affects the operational figure.

EmissionBase® helps separate operational energy from broader lifecycle CO₂ assumptions such as production, transport, maintenance and end-of-life treatment. This keeps the power figures from the datasheets distinct from modelled lifecycle estimates.

How this asset fits into wider turning coverage

Within Haas's own range, the ST turning centers sit next to related lathe families that handle jobs the standard ST is not built for. The dual-spindle DS machines transfer parts between a main and secondary spindle for done-in-one turning, the CL chucker lathes target small compact parts, and toolroom lathes serve simpler manual-style work. The ST Series is the general-purpose, single-spindle core of that line-up.

Across the market, the ST Series competes with turning center ranges from other machine tool makers, and within the broader taxonomy it sits alongside adjacent asset types such as turning-milling centers and multi-spindle automatic lathes, as well as Haas's own milling machines and machining centers. Comparisons are most meaningful within a matched size and spindle class rather than across the whole family at once.

The takeaway: the ST Series is the single-spindle turning core of a wider machine tool line-up, best compared within a matched size and spindle class.