Mitsui Seiki Horizontal Machining Centers

Mitsui Seiki HU100A

$1,200,000 - $2,000,000 Updated 2026-03-16

Key Specifications

X Travel

1,400 mm (55.1 in)

Y Travel

1,200 mm (47.2 in)

Z Travel

1,200 mm (47.2 in)

Spindle Taper

No. 50 (CAT50 / BT50 / HSK-A100)

Tool Capacity

60 (standard) / 120 (optional)

Rapid Traverse

36 m/min (1,417 ipm) all axes

Overview

The Mitsui Seiki HU100A is a large-format precision horizontal machining center with a 1,000 mm pallet, positioned at the top of Mitsui Seiki's horizontal line for manufacturers requiring the company's signature micron-level accuracy on large structural aerospace, defense, and energy sector components. At this scale — 1,000 mm pallet, 1,400 mm X-axis travel, and 1,500 kg maximum workpiece weight — the HU100A occupies a market segment where the combination of size and guaranteed accuracy is essentially unique among Japanese machine tool builders.

Despite its scale, the HU100A maintains Mitsui Seiki's ±0.002 mm full-stroke positioning accuracy (a slightly relaxed specification versus the HS5A/HS6A at this travel length, but exceptional for a 1,000 mm pallet class machine) with ±0.001 mm repeatability. Linear scale feedback on all axes and thermal compensation via oil-cooled spindle and ballscrew systems maintain this accuracy across extended production runs for large, high-value workpieces.

The 1,000 mm pallet handles workpieces up to 1,400 mm diameter and 1,600 mm height — encompassing large aerospace bulkheads, submarine valve bodies, turbine casings, and large mold bases. The spindle is a No. 50 taper, 6,000 RPM unit (8,000 RPM optional) at 37 kW (50 hp) continuous for heavy material removal in titanium, Inconel, and steel. A 60-tool ATC with optional 120-tool magazine supports long unattended runs. The FANUC 31i-B5 control includes Mitsui Seiki's thermal compensation cycles tailored to large-machine thermal gradients.

The HU100A competes with large HMCs from Heller, MAG, and Toshiba Machine (Shibaura), but Mitsui Seiki's accuracy pedigree and single-factory quality control are the differentiation for critical aerospace and defense programs.

Full Specifications

Parameter	Value
Pallet Size	1,000 mm x 1,000 mm (39.4 x 39.4 in)
X-Axis Travel	1,400 mm (55.1 in)
Y-Axis Travel	1,200 mm (47.2 in)
Z-Axis Travel	1,200 mm (47.2 in)
Max Workpiece Diameter	1,400 mm (55.1 in)
Max Workpiece Height	1,600 mm (63.0 in)
Max Workpiece Weight	4,000 kg (8,818 lb)
Spindle Taper	No. 50 (CAT50 / BT50 / HSK-A100)
Spindle Speed	6,000 RPM (standard) / 8,000 RPM (option)
Spindle Motor Power	37 kW (50 hp) continuous / 45 kW (60 hp) 30-min
Spindle Torque	2,500 Nm (1,844 ft-lb) peak
Rapid Traverse Rate	36 m/min (1,417 ipm) all axes
Feed Rate	1–10,000 mm/min
Positioning Accuracy	±0.002 mm (±0.00008 in) full stroke
Repeatability	±0.001 mm (±0.00004 in)
Rotary Table Resolution	0.001°
Feedback	Full-closed loop, linear scales all axes, rotary encoder B-axis
Thermal Compensation	Spindle oil cooling, ballscrew coolant, column temperature sensing and compensation
Tool Capacity	60 (standard) / 120 (optional)
Tool Change Time	5.0 sec (chip-to-chip)
Max Tool Diameter	250 mm (clearance); 125 mm (adjacent pockets occupied)
Max Tool Length	600 mm
Max Tool Weight	25 kg
Pallet Changer	2-station APC (standard)
Pallet Change Time	35 sec
Way Type	Box ways (X, Y, Z) — induction hardened and precision ground
Base Material	Meehanite cast iron, stress-relieved
CNC Control	FANUC 31i-B5
Machine Weight	65,000 kg (143,300 lb)
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Strengths & Limitations

Strengths

±0.002 mm positioning accuracy on a 1,000 mm pallet at 1,400 mm X travel is exceptional — competing large HMCs at this scale typically specify ±0.005 mm or do not guarantee positioning
4,000 kg maximum workpiece capacity on a precision machine enables large aerospace and defense structural parts that previously required less accurate bridge mills
37 kW No. 50 spindle with 2,500 Nm peak torque handles aggressive material removal in titanium, Inconel, and large steel components
Full thermal compensation including column temperature sensing addresses the unique thermal challenges of large machine structures
60–120 tool capacity supports complex multi-operation part families on large tombstone fixtures with minimal setup changes
Mitsui Seiki's single-factory quality control — calibrated by the same team that builds small precision HMCs — extends to this large-format machine

Limitations

Price of $1.2–2M requires a compelling business case — typically justified only by aerospace, defense, or energy sector programs with large, high-value parts
Machine weight of 65,000 kg requires significant foundation engineering — concrete pit or reinforced pad specifications must be developed early
6,000 RPM base spindle is suited to large-diameter tooling and heavy cuts but not to high-speed finishing — a secondary finishing machine may be needed
36 m/min rapids are modest at this scale — cycle times for large workpieces with long axis traverses can be significant
Long lead times of 9–18 months are typical; the HU100A is a configured-to-order machine at low annual volumes

Best For

Aerospace prime contractors and Tier 1 suppliers machining large structural components — bulkheads, spars, frames — to certified tolerances Defense manufacturers producing large precision housings, valve bodies, and structural components for naval, armored, and aircraft programs Power generation and energy sector manufacturers machining large turbine casings, impeller housings, and pressure vessel components Large precision mold builders producing injection mold bases and dies for automotive and aerospace composite tooling Research and government manufacturing facilities requiring large-format certified accuracy for scientific instrument and test equipment fabrication

Frequently Asked Questions

01 What is the foundation requirement for the HU100A?

At 65,000 kg, the HU100A requires a purpose-engineered machine foundation. Mitsui Seiki provides foundation drawing packages specifying concrete type, reinforcement, isolation joint design, and leveling pad placement. Typical foundation preparation takes 4–8 weeks and must be completed before the machine ships. Coordinate with your facilities team and a structural engineer at the time of order.

02 How does the HU100A handle thermal growth across its large structure?

Large machine structures experience greater thermal gradients than small machines because the column and base span longer distances. The HU100A addresses this with oil-cooled spindle (prevents spindle nose drift), ballscrew coolant (prevents thermal extension of drive screws), temperature sensors in the column and bed, and a FANUC 31i-B5 thermal compensation cycle that applies real-time position corrections based on measured temperature gradients. This system maintains ±0.002 mm accuracy even as the building temperature fluctuates.

03 Can the HU100A machine titanium and Inconel at production rates?

Yes. The 37 kW, 2,500 Nm No. 50 spindle supports industry-standard material removal rates in Ti-6Al-4V (typically 25–60 cm³/min with modern tooling) and Inconel 718 (8–20 cm³/min). The box way construction provides the rigidity needed to avoid chatter at these feed rates in difficult alloys. For maximum throughput in heavy aerospace alloys, discuss tooling strategy with your cutting tool supplier alongside the machine specification.

04 What is the typical customer profile for the HU100A?

The HU100A is purchased by aerospace Tier 1 suppliers with large structural programs (think F-35 bulkheads, satellite structures, or large aircraft wing attachment fittings), naval defense contractors producing large precision housings, power generation companies machining turbine components, and occasionally by national laboratories and research institutions. It is not a machine for general job shops — the business case requires consistent production of large, high-value precision components.