OKK HM-800S

$800,000 - $1,100,000 Updated 2026-03-17

Key Specifications

X Travel

1,000 mm (39.4 in)

Y Travel

900 mm (35.4 in)

Z Travel

950 mm (37.4 in)

Max Spindle

6,000 RPM (8,000 RPM optional)

Spindle Taper

BT 50 / HSK-A100

Rapid Traverse

50 m/min (X/Y/Z)

Overview

The OKK HM-800S is a large-pallet horizontal machining center from OKK Corporation, a Osaka-based Japanese machine tool manufacturer with over a century of history focused on precision machining equipment. The HM-800S serves the upper tier of prismatic part machining — large automotive castings, aerospace structural components, heavy equipment housings, and large mold bases — with an 800 mm pallet class that accommodates workpieces exceeding what 630 mm HMCs can handle. OKK's precision manufacturing heritage, built on the Japanese tradition of meticulous geometric accuracy and long-term dimensional stability, is fully expressed in the HM-800S.

OKK's philosophy in the HM series emphasizes absolute geometric accuracy and long-term machine reliability over peak axis speed. The HM-800S base and column are heavy cast iron structures, thermally symmetric in design and heavily ribbed for maximum stiffness. Finite element analysis guided the structural design to minimize deflection under heavy cutting loads — a requirement in the machine's target applications where workpiece weight alone can approach or exceed 1,500 kg. The B-axis rotary table uses a precision Hirth coupling for positive, rigid indexing at each 1-degree step, maintaining positioning rigidity equivalent to a fixed-table machine when locked.

The spindle on the HM-800S is a BT 50 or HSK-A100 configuration rated to 6,000 or 8,000 RPM with a 37 kW motor providing high torque for aggressive steel and cast iron roughing. OKK's spindle engineering emphasizes long-term accuracy retention — pre-loaded angular contact bearings with precision tolerance assembly minimize thermal growth and maintain the spindle's geometric relationship to the machine axes across temperature variation. OKK backs this with a spindle warranty and documented thermal growth specifications.

The ATC on the HM-800S is a matrix-type or arm-type magazine in 60-tool standard configuration, with 90 and 120-tool options for complex multi-operation programs. Dual-pallet configuration is standard, enabling the operator to set up the next workpiece while the machine cuts, maintaining high spindle utilization rates. Pallet change time in the 15–20 second class is consistent with production-class HMC operation.

The OKK HM-800S is priced in the $800,000 to $1,100,000 range — a premium over Taiwanese HMCs at equivalent pallet size, reflecting OKK's Japanese precision manufacturing, factory calibration rigor, and long-term geometric stability. Buyers in automotive and aerospace production environments who depend on dimensional consistency across years of production operation rather than only at initial installation acceptance are the target audience for this investment level.

Full Specifications

Parameter	Value
Pallet Size	800 x 800 mm (31.5 x 31.5 in)
X-Axis Travel	1,000 mm (39.4 in)
Y-Axis Travel	900 mm (35.4 in)
Z-Axis Travel	950 mm (37.4 in)
B Axis Indexing	1° increments (Hirth coupling)
Max Workpiece Weight	1,500 kg (3,307 lb) per pallet
Max Spindle Speed	6,000 RPM (8,000 RPM optional)
Spindle Taper	BT 50 / HSK-A100
Spindle Motor Power	37 kW (50 hp)
Spindle Torque	600 Nm peak
Rapid Traverse Rate	50 m/min (X/Y/Z)
Feed Rate Max	20,000 mm/min
Tool Changer Capacity	60 tools standard (90 / 120 optional)
Tool Change Time	5.0 sec (tool-to-tool)
Pallet Change Time	17 sec
Positioning Accuracy	±0.002 mm
Repeatability	±0.001 mm
Guideway Type	Linear roller guideways (X/Y/Z)
Through Spindle Coolant	70 bar standard
CNC Control	Fanuc 31i-B5 (Siemens 840D sl optional)
Machine Weight	32,000 kg (70,548 lb) approx.

Specifications sourced from methodsmachine.com — verified 2026-03-28

Strengths & Limitations

Strengths

±0.002 mm positioning accuracy and ±0.001 mm repeatability on an 800 mm pallet HMC represent Japanese Tier 1 geometric standards, providing a measurable accuracy margin over Taiwanese HMC competitors at this pallet size
Heavy cast iron base and column construction with FEA-optimized rib geometry provides superior static and dynamic stiffness, reducing vibration-induced surface roughness in heavy steel and cast iron production cutting
OKK's spindle engineering emphasis on long-term accuracy retention means that geometric specifications at 5-year machine age are closer to initial installation specifications than many competitors — critical for automotive production where part tolerances are guaranteed across a vehicle model's production run
37 kW / 600 Nm spindle delivers the power and torque profile for sustained heavy roughing of large steel and cast iron workpieces without spindle thermal overload, maintaining material removal rates through long-cycle production programs
120-tool ATC option enables complex multi-operation programs with full tool complements for all roughing, semi-finishing, and finishing operations to run without tool magazine intervention

Limitations

$800K–$1.1M pricing is at the high end for 800 mm pallet HMCs — buyers without a clear requirement for OKK's accuracy tier and long-term stability can find comparable work envelope at lower cost from Taiwanese or Korean HMC manufacturers
OKK's North American and European dealer network, while capable, is less extensive than Mazak, DMG Mori, or Okuma — regional service coverage and parts availability may be less convenient than the larger brand alternatives
6,000–8,000 RPM spindle speed is appropriate for steel and cast iron production but limits efficiency in aluminum machining compared to higher-speed alternatives — shops with a significant aluminum mix should evaluate spindle speed requirements carefully

Best For

Automotive Tier 1 and Tier 2 suppliers producing large cast iron engine blocks, transmission cases, and differential housings in high-volume production environments where long-term dimensional consistency across years of production is a contractual requirement Aerospace manufacturers machining large aluminum and titanium structural components — wing ribs, spars, and bulkheads — where OKK's accuracy tier and structural rigidity justify the premium over lower-tier HMC alternatives Heavy equipment and off-highway machinery manufacturers producing large hydraulic pump bodies, gearbox cases, and frame components where workpiece weight and size demand 800 mm pallet capacity with high payload ratings Precision contract manufacturers who have won OEM contracts requiring documented dimensional stability and machine capability indices (Cpk) that only Japanese Tier 1 HMC accuracy can reliably support

Frequently Asked Questions

01 How does the OKK HM-800S compare to the HM-1000S?

The HM-800S uses an 800 mm pallet and targets the mid-large prismatic production segment. The HM-1000S scales to a 1,000 mm pallet for workpieces that exceed the HM-800S's dimensional capacity — very large castings, structural aerospace assemblies, and large mold bases. Both machines share OKK's precision manufacturing approach and heavy cast iron structure, with the HM-1000S at proportionally higher price and larger floor footprint. The HM-800S is the right choice when 800 mm accommodates all parts in the product mix; the HM-1000S is necessary when any part family regularly exceeds 800 mm in the critical dimension.

02 What long-term accuracy guarantees does OKK provide for the HM-800S?

OKK does not typically offer a contractual long-term accuracy guarantee in the standard commercial sense, but the company's engineering philosophy — heavy cast iron structures, thermally-symmetric design, precision bearing assembly, and documented thermal growth specifications — is oriented toward long-term accuracy retention. OKK provides factory acceptance test documentation covering all geometric specifications at the time of shipment. Buyers in automotive production who require machine capability documentation (Cmk/Cpk) should conduct their own acceptance testing at installation and periodically thereafter, using the OKK factory test specifications as the baseline.

03 Is the OKK HM-800S suitable for automation and FMS integration?

Yes. The HM-800S's dual-pallet configuration is the foundation for flexible manufacturing system integration. OKK provides interface protocols for connection to external pallet pool systems, rail-guided vehicle (RGV) systems, and FMS controller software. The machine's Fanuc 31i-B5 control supports the remote job start, tool life management, and status communication interfaces required for FMS coordination. OKK has installed HM-800S machines in multi-machine FMS configurations at Japanese and global automotive suppliers, with experience in both linear pallet pool and circular carousel FMS architectures.

04 What is the tool capacity and tool size envelope for the HM-800S ATC?

The standard HM-800S ATC holds 60 tools in a matrix-type magazine. Optional capacities of 90 and 120 tools are available for programs requiring larger tool complements. Maximum tool diameter is 125 mm in adjacent pockets occupied, 250 mm with adjacent pockets empty. Maximum tool length is 550 mm. Maximum tool weight is 20 kg. These limits accommodate standard end mills, drills, taps, reamers, and BT 50 / HSK-A100 boring bar assemblies used in production prismatic machining of large workpieces.

05 Can the OKK HM-800S machine titanium aerospace components?

Yes, titanium machining is a core application for the HM-800S. Titanium requires specific cutting conditions — lower cutting speeds than aluminum (typically 40–60 m/min surface speed with carbide tooling), higher feed per tooth to avoid work-hardening, and aggressive through-spindle coolant (70 bar standard on the HM-800S) to manage heat at the cutting zone and prevent built-up edge formation. The machine's 37 kW / 600 Nm spindle provides adequate torque for titanium at the required feed rates. OKK's structural rigidity is an advantage in titanium: vibration that causes chatter in lighter-duty machines is better controlled by the HM-800S's heavy cast iron structure.