Citizen Miyano BNJ-42S
Key Specifications
max bar capacity sp1
max bar capacity sp2
max machining length
main spindle speed
main spindle power
sub spindle speed
Overview
The Citizen Miyano BNJ-42S is a twin-turret, twin-spindle fixed-headstock CNC lathe engineered for high-production machining of parts up to 42 mm diameter. The BNJ-42S is the base model in the BNJ-42 family — dual turrets without Y-axis — providing true simultaneous independent machining on both spindles at the lowest entry point in the twin-turret 42 mm lineup.
The main spindle (SP1) runs from 60 to 6,000 RPM with 15/11 kW (20/15 hp), while the sub-spindle (SP2) reaches 5,000 RPM with 7.5/5.5 kW (10/7.5 hp). Bar capacity is 42 mm on both spindles. The upper turret (HD1) has 12 stations with live tools running at 6,000 RPM, and the lower turret (HD2) has 8 stations with live tools at 3,000 RPM. This 12+8 configuration provides 20 tool positions for complex multi-operation parts.
Axis travels measure 165 mm on X1, 246 mm on Z1, 85 mm on X2, and 590 mm on Z2. Maximum machining length is 100 mm. The generous 590 mm Z2 travel provides ample clearance for part transfer between spindles and extended backworking operations.
At 5,300 kg with a floor space of 2,840 x 1,560 mm and machine height of 1,700 mm, the BNJ-42S is a substantial production machine built for environments where dual-turret cycle time reduction directly impacts profitability. The Mitsubishi M80W dual-path control handles the synchronization required for independent turret operation.
The BNJ-42S delivers the core benefit of dual-turret independence — 30-50% cycle time reduction on parts with balanced front-and-back operations — without the added cost of Y-axis. For shops producing parts where the primary operations are turning, drilling, and threading without off-center milling requirements, the BNJ-42S provides maximum productivity at a lower price point than the Y-axis-equipped BNJ-42SY.
Full Specifications
| Parameter | Value |
|---|---|
| Max Bar Capacity Sp1 | 42 mm (1.65 in) |
| Max Bar Capacity Sp2 | 42 mm (1.65 in) |
| Max Machining Length | 100 mm (3.94 in) |
| Main Spindle Speed | 60 - 6,000 RPM |
| Main Spindle Power | 15/11 kW (20/15 hp) |
| Sub Spindle Speed | 50 - 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 |
| Lower Turret Live Tool Speed | 3,000 RPM |
| 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) |
| Power Chuck Sp1 | H-S20 / DIN173E |
| Power Chuck Sp2 | H-S16 / DIN171E |
| Machine Weight | 5,300 kg |
| Floor Space | 2,840×1,560mm(Without Chip Conveyor) |
| Machine Height | 1,700 mm |
| CNC Control | Mitsubishi M80W dual-path |
| Items | BNJ-42S6 |
| Machining Capacity | Standard Turning Length |
| Standard Machining Diameter | SP1/SP2 |
| Spindle | Spindle Speed Range |
| Sp2 | JPN, H-S16, DIN171E |
| Type Of Collet Chuck | SP1 |
| Type Of Power Chuck | SP1/SP2 |
| Turret | Type of Turret |
| Hd2 | M10×1.0 |
| Revolving Tools | Maximum Number of Revolving Tools |
| Spindle Speed Range | HD1 |
| Maximum Drilling Diameter | HD1 |
| Maximum Tapping Diameter | HD1 |
| Slide Stroke | Turret Slide Stroke |
| Z1 Axis | 246mm |
| Spindle Slide Stroke | X2 axis |
| Z2 Axis | 590mm |
| Motors | Spindle Motor |
| Sp2 Cs | 7.5/5.5kw(15min./Cont.) |
| Machine Dimensions | Machine Height |
| Sliding Headstock Type | A20 |
| Bar Work | BNC42 |
| Turning Machine | BNA42CY |
| High Precision Turning Machines | BNA42SY |
| Multi Station Machining Cell | MC20 III |
| Standard Turning Length Sp1 Sp2 | 100mm |
| Standard Machining Diameter Sp1 Sp2 | 51mm Dia./42mm Dia. |
| Spindle Speed Range Sp1 | 50 - 5,000min-1 |
| Spindle Speed Range Sp2 | 50 - 5,000min-1 |
| Type Of Collet Chuck Sp1 | H-S22, DIN177E |
| Type Of Collet Chuck Sp2 | JPN, H-S16, DIN171E |
| Type Of Power Chuck Sp1 Sp2 | 6"/5" Hollow |
| Type Of Turret Hd1 | 12st. |
| Type Of Turret Hd2 | 8st. |
| Maximum Number Of Revolving Tools Hd1 | Max.12 |
| Maximum Number Of Revolving Tools Hd2 | Max.4 |
| Spindle Speed Range Hd1 | 6,000min-1 |
| Maximum Drilling Diameterhd1 | 13mm Dia. |
| Maximum Drilling Diameterhd2 | 10mm Dia. |
| Maximum Tapping Diameter Hd1 | M12×1.75 |
| Maximum Tapping Diameter Hd2 | M10×1.0 |
| Turret Slide Stroke X1 Axis | 165mm |
| Turret Slide Stroke Z1 Axis | 246mm |
| Spindle Slide Stroke X2 Axis | 85mm |
| Spindle Slide Stroke Z2 Axis | 590mm |
| Spindle Motor Sp1 Cs | 15/11kw(15min./Cont.) |
| Spindle Motor Sp2 Cs | 7.5/5.5kw(15min./Cont.) |
| Spindle Speed Range Hd2 | 3,000min-1 |
| Maximum Drilling Diameter Hd1 | 13mm Dia. |
| Turret Slide Stroke Y Axis | ±40mm |
| Maximum Drilling Diameter Hd2 | 10mm Dia. |
| Inquiries | Feel free to get in touch with us by phone or online if you have any questions or need advice about any of our products or services. |
Specifications sourced from cmj.citizen.co.jp — verified 2026-03-28
Strengths & Limitations
Strengths
- True dual-turret independence enables simultaneous machining on both spindles, reducing cycle times 30-50% on parts with balanced front-and-back operations
- 15/11 kW main spindle provides 20/15 hp for aggressive roughing across the full 42 mm bar capacity range in steel and stainless materials
- Full 42 mm bar capacity on both spindles ensures complete backworking capability without sub-spindle diameter limitations
- 590 mm Z2 travel provides exceptional clearance for part transfer and extended backworking operations
- 12+8 station turret configuration provides 20 total tool positions for complex multi-operation parts
- Lower entry cost than the Y-axis-equipped BNJ-42SY for shops that primarily need turning, drilling, and threading
Limitations
- No Y-axis capability limits the machine to on-center operations only — flats, keyways, and hexagonal profiles require the SY variant
- 3,000 RPM lower turret live tool speed is half the upper turret's 6,000 RPM, limiting backworking milling performance
- 5,300 kg weight and 2,840 x 1,560 mm footprint is substantially larger than single-turret BNA machines
- Dual-path programming complexity requires experienced multi-turret programmers and collision simulation software
Best For
Frequently Asked Questions
01
New BNJ-42S6 machines typically range from $200,000 to $280,000 depending on tooling configuration and automation accessories. The no-Y-axis configuration positions it below the BNJ-42SY by approximately $30,000-$50,000. Used BNJ-42S machines are relatively rare on the secondary market.
02
The SY adds Y-axis travel of +/-40 mm for off-center milling, drilling, and tapping. The BNJ-42S is limited to on-center driven tool operations. Choose the S for primarily turning-focused parts; choose the SY when parts require flats, keyways, or hexagonal profiles.
03
The lower turret's 3,000 RPM is designed for lighter backworking operations — cross-drilling, tapping, and light milling on the sub-spindle. The upper turret's 6,000 RPM handles heavier milling on the main spindle. This asymmetric design reflects the typical part: most milling complexity is on the front end.
04
Yes, the BNJ-42S can operate in single-turret mode, using only the upper turret. This is useful during setup, prototyping, or when running simpler parts that do not benefit from simultaneous operations.
Videos
ConcentricCorp
actmachinery
Citizen Machinery UK
Citizen Machinery UK
NEWEMAG | Schneider mc
