Citizen Miyano BNJ-51SY6

$280,000 - $390,000 Updated 2026-03-19

Key Specifications

max bar capacity sp1

51 mm (2.0 in)

max bar capacity sp2

42 mm (1.65 in)

main spindle speed

5,000 RPM

main spindle power

15/11 kW (20/15 hp)

sub spindle speed

5,000 RPM

sub spindle power

7.5/5.5 kW (10/7.5 hp)

Overview

The Citizen Miyano BNJ-51SY6 is the sixth-generation twin-turret, twin-spindle fixed-headstock CNC lathe with Y-axis in the BNJ-51 platform, delivering true simultaneous independent machining with off-center milling capability from 51 mm bar stock. The current SY6 generation represents Citizen's most capable machine for high-volume production of complex medium-sized turned parts.

The main spindle (SP1) reaches 5,000 RPM with 15/11 kW (20/15 hp), while the sub-spindle (SP2) runs to 5,000 RPM with 7.5/5.5 kW (10/7.5 hp). The main spindle accepts 51 mm bar stock while the sub-spindle handles 42 mm. The upper turret (TR1) has 12 stations with live tools at 6,000 RPM and 2.2 kW of rotary tool power, plus Y-axis travel of +/-40 mm. The lower turret (TR2) adds 8 stations with live tools at 6,000 RPM.

Axis travels measure 168 mm on X1, 250 mm on Z1, 88 mm on X2, and 650 mm on Z2. The 650 mm Z2 travel is the longest in the BNJ family, providing exceptional clearance for part transfer and extended backworking. Seven cutting axes provide the motion freedom for complex multi-path programming. The 825 mm distance between spindle faces accommodates the twin-turret arrangement comfortably.

At 5,550 kg with a floor space of 2,881 x 1,578 mm and machine height of 1,775 mm, the BNJ-51SY is a substantial production machine. The Fanuc 0i-TF control manages dual-path synchronization with broad CAM post processor compatibility.

The BNJ-51SY sits at the apex of the Miyano 51 mm platform. It competes with the Nakamura-Tome WY-150 and similar premium twin-turret machines. Automotive transmission components, hydraulic fittings, medical device housings, and industrial connectors where twin-turret simultaneous machining with Y-axis milling shaves critical seconds from every cycle are the applications that justify its premium price point.

Full Specifications

Parameter	Value
Max Bar Capacity Sp1	51 mm (2.0 in)
Max Bar Capacity Sp2	42 mm (1.65 in)
Main Spindle Speed	5,000 RPM
Main Spindle Power	15/11 kW (20/15 hp)
Sub Spindle Speed	5,000 RPM
Sub Spindle Power	7.5/5.5 kW (10/7.5 hp)
Upper Turret Stations	12
Lower Turret Stations	8
Upper Turret Live Tool Speed	6,000 RPM
Upper Turret Live Tool Power	2.2 kW
Lower Turret Live Tool Speed	3,000 RPM
Y Axis Travel	80 mm (+/-40 mm)
Travel X1	165 mm (6.50 in)
Travel Z1	246 mm (9.69 in)
Travel X2	85 mm (3.35 in)
Travel Z2	590 mm (23.23 in)
Number Of Axes	7 cutting axes
Distance Between Spindles	825 mm
Max Drilling Tr1	13 mm
Max Tapping Tr1	M12 x 1.75
Standard Collection Length	120 mm
Machine Weight	5,550 kg (12,235 lb)
Floor Space	2,630 Ã 1,540 mm
Machine Height	1,775 mm
CNC Control	Fanuc 0i-TF
Rapid Traverse Xz	20 m/min (787 ipm)
Rapid Traverse Y	12 m/min (472 ipm)
Lower Turret Live Tool Power	0.75 kW
Item	BNJ-51SY6
Max Machining Length	100 mm
Bar Capacity	51 mm / 42 mm Dia.
Draw Tube Diameter	â 52 mm / â 43 mm
Collet Chuck Type	H-S22 / H-S16 (DIN171E)
Power Chuck Size	6" Thru-hole / 5" Thru-hole
Turret No 1 No 2	12 Station / 8 Station
Revolving Tools	Max. 12 (Single Clutch) / Max. 4 (Simultaneous)
Tool Spindle Speed	6,000 rpm / 3,000 rpm
Shank Size	3/4" Sq. / 1" Dia.
Drilling Capacity	Max â 13 mm / Max â 10 mm
Tapping Capacity	Max M12 / Max M6
Rapid Feed Rate	12 m/min
Turret Stroke	165 mm / 246 mm / 80 (Â±40) mm
Sub Spindle Stroke	85 mm / 590 mm
Spindle Motor	15/11 kW / 7.5/5.5 kW
Revolving Tool Motor	2.2 kW / 0.75 kW
Input Power Fuse Capacity	33 KVA / 100 A
Coolant Tank Capacity	300 L

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

Strengths & Limitations

Strengths

True twin-turret independence with Y-axis delivers the most capable simultaneous machining configuration in the 51 mm Miyano platform
6,000 RPM live tools on both turrets provide full milling capability for cross-drilling, tapping, and off-center features on both front and back of the workpiece
Y-axis travel of +/-40 mm handles complex off-center milling for flats, keyways, and hexagonal profiles on the main spindle
650 mm Z2 travel provides exceptional clearance for part pickup and backworking, handling longer parts without interference
15/11 kW main spindle delivers ample power for aggressive roughing at the 51 mm bar diameter in steel and stainless materials
Fanuc 0i-TF control offers broad CAM post processor compatibility and is familiar to the majority of CNC programmers

Limitations

42 mm sub-spindle capacity is smaller than the 51 mm main spindle, restricting full-diameter backworking on the largest parts
5,550 kg weight and 2,881 x 1,578 mm footprint requires significant floor space and foundation work
Twin-turret Y-axis programming complexity requires experienced multi-path programmers and collision simulation software
Premium pricing requires consistent high-volume work to justify over simpler single-turret alternatives

Best For

Automotive transmission component production where twin-turret simultaneous machining with Y-axis milling provides maximum cycle time reduction Hydraulic fitting and connector manufacturers running large quantities of parts with balanced front-and-back complexity in the 42-51 mm range Medical device housing production where twin-turret capability reduces cycle time enough to justify the premium over single-turret machines Industrial connector and coupling manufacturers producing parts from 51 mm bar with cross-drilling, milling, and threading on both ends Shops running the BND-51SY at capacity that need to increase throughput without adding a second machine

Frequently Asked Questions

01 What does a new Citizen Miyano BNJ-51SY cost?

New BNJ-51SY6 machines typically range from $260,000 to $370,000 depending on tooling configuration, high-pressure coolant, bar feeder, and parts catcher. The twin-turret Y-axis design commands a $70,000-$100,000 premium over single-turret BND-51SY alternatives.

02 Why does the sub-spindle only accept 42 mm bar when the main spindle takes 51 mm?

The 42 mm sub-spindle is a design trade-off that keeps the sub-spindle assembly compact enough to travel the full 650 mm Z2 stroke without interference. Most 51 mm bar parts have backworking features within 42 mm diameter. For parts needing full 51 mm backworking, check with Citizen for optional sub-spindle configurations.

03 What generation is the current BNJ-51SY?

The current model is the BNJ-51SY6, featuring the Fanuc 0i-TF control. Each generation has brought incremental improvements in turret rigidity, spindle performance, and control features. The SY7 generation is beginning to appear at trade shows.

04 Can the BNJ-51SY handle both bar and chucker work?

Yes. The machine supports both collet and power chuck workholding. With power chucks, it handles castings, forgings, and pre-cut blanks. Most shops maintain both setups for flexibility between bar-fed and chucker production.