Star SR-20J

$180,000 - $320,000 Updated 2025-03-15

Key Specifications

Max Spindle

10,000min-1

Rapid Traverse

32 m/min

Spindle Power

2.2kw (continuous) / 3.7kw (15min./60%ED)

Max Turn Length

205mm (8in) Type C / Bar diameterx2.5 Type N

max bar capacity

20 mm (0.787 in)

max machining diameter

20 mm (0.787 in)

Overview

The Star SR-20J is one of the most popular and widely installed Swiss-type CNC automatic lathes in the world, representing Star Micronics' standard-range (SR) platform in the critical 20mm bar capacity class. With up to 9 axes including Y-axis capability, extensive live tooling, and Star's proven guide bushing technology, the SR-20J delivers the versatility to handle everything from simple turned components to complex multi-feature parts requiring milling, angular drilling, and full backworking—all in a single setup.

The SR-20J features a main spindle reaching 10,000 RPM and a back spindle at 8,000 RPM, both with built-in motor designs for smooth, vibration-free operation. The Y-axis provides the off-center machining capability essential for flats, hexagons, keyways, and complex milled features that have become standard requirements across medical, aerospace, and automotive Swiss-type work. Up to 27 tool positions including multiple live tool stations provide the tooling density needed to complete complex parts in a single cycle, minimizing setup time and eliminating secondary operations.

Star's Motion Control System (MCS) is a key differentiator on the SR-20J, providing intelligent axis management that optimizes cycle times by coordinating simultaneous multi-path operations. The system reduces non-cutting time and enables overlapping front and back operations, delivering meaningful cycle time reductions on complex parts. The Fanuc 31i-B5 control handles the multi-axis coordination with proven reliability, and Star's programming environment simplifies the creation of complex synchronized programs.

The SR-20J is available in multiple configurations including guide bushing and non-guide bushing (NGB) options. The NGB capability is valuable for shorter parts where the reduced bar remnant waste improves material utilization. Star's hydraulic-free design reduces environmental impact and maintenance costs by eliminating hydraulic oil, filters, and associated maintenance tasks. This environmentally conscious approach, combined with industry-leading precision and reliability, has made the SR-20J the Swiss lathe of choice for thousands of shops worldwide.

Full Specifications

Parameter	Value
Max Bar Capacity	20 mm (0.787 in)
Max Machining Diameter	20 mm (0.787 in)
Max Machining Length	205 mm (8.07 in)
Main Spindle Speed	10,000 RPM
Back Spindle Speed	8,000 RPM
Live Tool Speed	9,000 RPM
Number Of Axes	Up to 9 (including Y1, Y2, C1, C2)
Tool Positions	27 (including live tools)
Y Axis Stroke	±15 mm
Guide Bushing	Yes (guide bushing and NGB configurations available)
CNC Control	Fanuc 31i-B5
Rapid Traverse Rate	32 m/min
Machine Weight	2,200kg
Power Consumption	10 kVA
Max Turning Diameter	ø20mm (25/32in)
Max Turning Length	205mm (8in) Type C / Bar diameterx2.5 Type N
Bar Capacity	ø20mm (25/32in)
Max Spindle Speed	10,000min-1
Spindle Motor Power	2.2kw (continuous) / 3.7kw (15min./60%ED)
Turret Stations	6 tools
Tool Shank	12mm
Rapid Traverse X	35m/min
Rapid Traverse Y	35m/min
Rapid Traverse Z	35m/min
Coolant Capacity	170ℓ
Floor Space	2,250 X 1,200 X 1,700mm
Cnc Control	Fanuc 31i-B
Electrical	5.2KVA

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

Strengths & Limitations

Strengths

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Limitations

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Best For

Medical device manufacturers producing complex bone screws, spinal implants, dental abutments, and surgical instruments Aerospace shops machining precision fittings, hydraulic connectors, and multi-feature actuator components Contract manufacturers needing maximum Swiss-type versatility to handle diverse customer part requirements Automotive Tier 1 suppliers producing high-precision fuel system, sensor, and safety-critical components Shops replacing older multi-spindle screw machines with modern Swiss-type capability Any shop producing complex parts in the 5-20mm range that currently require secondary operations after Swiss machining

Frequently Asked Questions

01 What does a Star SR-20J cost?

A new Star SR-20J ranges from approximately $180,000 for a basic configuration to $320,000 for a fully equipped 9-axis model with maximum tooling and options. Used SR-20J machines from 2010-2020 typically sell for $60,000-$160,000 depending on configuration, hours, and condition.

02 What is Star's Motion Control System (MCS)?

MCS is Star's proprietary axis management technology that optimizes cycle times by intelligently coordinating simultaneous multi-path operations. It reduces non-cutting time by overlapping tool movements, synchronizing front and back operations, and minimizing idle time between operations. MCS can reduce cycle times by 10-30% on complex parts.

03 How does the SR-20J compare to the Citizen L20?

Both are premium 20mm Swiss lathes. The SR-20J offers hydraulic-free design, MCS, and up to 27 tools. The Citizen L20 offers LFV chip-breaking technology and up to 8 model variants. The SR-20J's hydraulic-free design reduces maintenance, while the L20's LFV excels in gummy materials. Both deliver excellent precision and are widely used in medical and aerospace.

04 What does hydraulic-free mean?

Star's hydraulic-free design uses electric servos for all clamping, guide bushing, and auxiliary functions that traditionally required hydraulic power. This eliminates hydraulic oil, filters, pumps, and hoses—reducing maintenance costs, eliminating oil disposal, reducing heat generation, and lowering environmental impact.

05 Can the SR-20J switch between guide bushing and NGB?

Yes, the SR-20J is available in configurations that support both guide bushing and non-guide bushing operation. Switching between modes requires some changeover time to add or remove the guide bushing assembly, but it gives shops the flexibility to optimize for precision (guide bushing) or material savings (NGB) based on part requirements.

06 What industries use the Star SR-20J most?

Medical devices is the single largest market for the SR-20J, followed by aerospace, automotive, electronics, and general precision manufacturing. The machine's versatility and precision make it a natural fit for any industry producing complex small parts in the 5-20mm range.