Kuraki KBM-11RX

$1,000,000 - $2,000,000 Updated 2026-03-17

Key Specifications

X Travel

4,000 mm (157 in) — column traverse

Y Travel

2,000 mm (78.7 in) — vertical

Z Travel

900 mm (35.4 in) — spindle axial

Max Spindle

2,500 RPM

Table Size

1,800 x 1,800 mm (70.9 x 70.9 in) rotary table

Rapid Traverse

12 m/min (472 ipm)

Overview

The Kuraki KBM-11RX is a CNC horizontal boring and milling machine in the medium-large class, built around an 110 mm (4.3 inch) boring spindle. Kuraki Co., Ltd., headquartered in Kurobe, Toyama Prefecture, Japan, has been manufacturing precision boring mills since 1935 and is one of Japan's most respected builders of large-format boring and milling machines. The KBM-11RX represents Kuraki's core horizontal boring mill product line, targeting the aerospace, energy, and heavy industrial manufacturing sectors where large-diameter precision boring combined with full milling capability is required.

The KBM designation stands for Kuraki Boring and Milling, and the 11 in the model number refers to the 110 mm spindle diameter — the primary capability parameter for a horizontal boring mill where spindle rigidity and diameter determine the maximum boring bar reach and the stiffness available for deep bore operations. The RX suffix designates the advanced control configuration with rotary table and expanded travel options. The machine uses a floor-type design with a traveling column, enabling machining of very large workpieces that are fixed to a floor plate or a rotary table mounted on the floor plate.

The KBM-11RX spindle is precision-ground and assembled with high-precision angular contact bearings to minimize radial runout — a critical parameter when boring large-diameter holes to H6 or H7 tolerance class over depths of 500 mm or more. The spindle can accept standard boring bars for diameter bores from 50 mm to over 600 mm in single and double passes. The column travels on precision linear guideways with anti-friction elements for smooth, stick-slip-free motion at all feed rates, which is essential when fine-feeding a boring bar through a finish bore pass.

Beyond boring, the KBM-11RX provides full CNC milling capability through a range of exchangeable spindle heads including right-angle heads, universal swiveling heads, and extended-reach heads stored in an automatic head changer. This makes the KBM-11RX a truly complete machining solution for large prismatic workpieces — turbine casings, compressor frames, large pump bodies, propulsion system housings — where boring and milling operations must be combined without moving the workpiece to a separate machine.

Kuraki machines are well-established in Japanese heavy industry and have a strong presence in North American aerospace and energy manufacturing, where Kuraki's reputation for precision and reliability has been built over decades of installed machines. The KBM-11RX competes with TOS Varnsdorf WRD 130, Parpas ML 40, Juaristi JXR, and Burkhardt+Weber MCX in the medium-large horizontal boring mill segment. Kuraki differentiates through Japanese manufacturing quality, Fanuc control integration, and a strong North American and European service presence compared to smaller European boring mill builders.

Full Specifications

Parameter	Value
Spindle Diameter	110 mm (4.33 in)
X-Axis Travel	4,000 mm (157 in) — column traverse
Y-Axis Travel	2,000 mm (78.7 in) — vertical
Z-Axis Travel	900 mm (35.4 in) — spindle axial
W Axis Travel	700 mm (27.6 in) — quill
Max Spindle Speed	2,500 RPM
Spindle Motor Power	45 kW (60.3 hp)
Spindle Torque	3,000 Nm at S1
Table Size	1,800 x 1,800 mm (70.9 x 70.9 in) rotary table
Max Workpiece Weight	20,000 kg (44,092 lb)
Rapid Traverse Rate	12 m/min (472 ipm)
Tool Taper	SK 50 / HSK-A100
CNC Control	Fanuc 31i-B5
Machine Weight	55,000 kg (121,254 lb) approximate

Strengths & Limitations

Strengths

110 mm precision-ground boring spindle with 3,000 Nm torque provides the rigidity and cutting force for large-diameter boring operations in steel, cast iron, and titanium to H6/H7 tolerance over deep reaches
Kuraki's Japanese manufacturing heritage from Toyama Prefecture delivers the precision assembly and quality control standards that make KBM machines among the most accurate boring mills in their class
Full multi-head automatic head changer capability — right-angle heads, universal heads, extended boring heads — transforms the KBM-11RX into a complete multi-operation machining center without workpiece repositioning
Fanuc 31i-B5 control with full 5-axis interpolation is the preferred control ecosystem for North American and Asian aerospace and energy manufacturers, ensuring strong local support and familiar programming environment
Strong Kuraki North American service presence, with established distributor and service networks in the US and Canada serving aerospace, defense, and energy sector customers

Limitations

Purchase price in the $1M–$2M range requires a clear large-part boring application and sufficient volume to justify; the KBM-11RX is not suitable for general-purpose machining or shops without a dedicated large-part program
Floor-type installation requires significant customer site preparation: poured concrete foundation, floor plate installation, and overhead crane access — total site preparation cost can add $100K–$300K to the investment
At 2,500 RPM maximum spindle speed, the KBM-11RX is optimized for boring and heavy milling rather than high-speed machining of aluminum; shops requiring high-speed aluminum contouring should consider a supplementary machine

Best For

Aerospace prime contractors and Tier 1 suppliers machining large structural components: engine pylons, landing gear housings, bulkhead frames, and large actuator housings requiring precision bores combined with milled features Energy sector manufacturers producing turbine casings, compressor housings, large valve bodies, and pump frames in carbon steel, stainless steel, and high-nickel alloys Naval and defense manufacturers producing large propulsion system housings, sonar dome frames, and naval vessel structural components requiring complete boring and milling in single setups Heavy industrial equipment OEMs machining large gearbox housings, mill head housings, and large press frames where bore-to-bore positional accuracy over large distances is critical

Frequently Asked Questions

01 What is the W-axis on the KBM-11RX?

The W-axis is the quill (boring bar sleeve) travel, which is independent of the Z-axis column traverse. The W-axis provides 700 mm of additional spindle extension travel for deep boring operations without moving the column. The W-axis extends the boring bar reach for operations where the column traverse alone cannot reach the target bore depth, and it allows fine-feeding the boring bar through finish bore passes at controlled feed rates for best bore finish and roundness.

02 What diameter bores can the KBM-11RX produce?

The 110 mm spindle accepts standard boring bar systems capable of machining bores from approximately 50 mm minimum diameter (with small adjustable boring heads) up to 2,000 mm or larger diameter (with long sweep boring arms). The practical bore diameter range for precision boring (< 10 µm roundness) is typically 80 mm to 800 mm. For very large diameter facing and boring operations (1,000 mm+), special boring arms and face plates are available as options.

03 What CNC control does the KBM-11RX use?

The standard control is the Fanuc 31i-B5, which provides full five-axis simultaneous interpolation capability, advanced boring cycles, thread milling cycles, and integration with Kuraki's thermal compensation system. The Fanuc control is preferred by most North American and Asian aerospace and energy manufacturers for its mature ecosystem, readily available training, and widespread service support.

04 Can the KBM-11RX perform thread milling?

Yes. Thread milling is a standard capability through the Fanuc 31i-B5 control's helical interpolation cycles. Large-diameter internal and external threads — common in turbine casing flanges, large valve bodies, and industrial machinery — can be thread-milled using carbide thread milling cutters in combination with the KBM-11RX's helical interpolation. This is generally preferred over single-point threading for large-diameter threads in tough materials.

05 What is the largest rotary table available for the KBM-11RX?

Kuraki offers rotary table options for the KBM series in sizes from 1,000 x 1,000 mm through 2,500 x 2,500 mm and larger custom configurations. The standard 1,800 x 1,800 mm table with 20,000 kg load capacity covers most large industrial workpieces. For very large workpieces — ship propeller hubs, large turbine casings — the workpiece may be mounted directly on the floor plate without a rotary table, with the column traveling around the workpiece for multiple-face machining.