Tornos Sigma 20 Multi-Spindle Automatic
Key Specifications
Number of Spindles
Max Bar Diameter
Max Spindle Speed
Spindle Motor Power
Bar Feed Capacity
Cross Slides
Overview
The Tornos Sigma 20 Multi-Spindle is a 6-spindle CNC multi-spindle automatic bar machine targeting high-volume production of precision components up to 20mm bar diameter. As the smaller-capacity sibling to the Sigma 32 in the Tornos multi-spindle lineup, the Sigma 20 is optimized for the large class of rotational parts in the 6mm to 20mm diameter range: connector bodies, miniature valves, medical implant hardware, watch components, and small automotive turned parts that require multi-feature machining at maximum throughput.
The Sigma 20 shares the cam-less CNC architecture that defines the Tornos multi-spindle platform. With no mechanical cams to change, job transitions are achieved through control parameter upload and tooling changeover — a significant operational advantage over legacy cam-driven multi-spindles in mixed-production environments. Each of the six spindle positions operates with independently controlled CNC slides, enabling complex operation sequences to be distributed across positions to minimize drum cycle time. Tornos C-More control manages all axis synchronization across positions with graphical simulation for pre-production verification.
At the 20mm bar diameter range, the Sigma 20 competes with Schutte 20mm multi-spindles, Index MS16-6 and MS22-6 platforms, and Star Micronics' multi-spindle offerings. The machine's Swiss design heritage places particular emphasis on dimensional precision and repeatability across high-volume production runs — a differentiator in precision markets where part-to-part consistency over millions of cycles matters as much as raw throughput.
The Sigma 20 is well-suited for lights-out production environments. Integrated bar feed compatibility, automatic parts conveyance, and the C-More control's production monitoring capabilities allow the machine to run extended unmanned cycles with minimal operator intervention. For precision component manufacturers producing high-mix, high-volume parts in the sub-20mm range, the Sigma 20 multi-spindle represents one of the most capable and flexible platforms available.
Full Specifications
| Parameter | Value |
|---|---|
| Number Of Spindles | 6 |
| Max Bar Diameter | 20 mm |
| Max Spindle Speed | 8,000 rpm |
| Spindle Motor Power | 15 kW (total installed) |
| Bar Feed Capacity | Front-loaded, 3.5 m bar standard |
| Cross Slides | 6 cross slides (one per position) + end-working slides |
| Control System | Tornos C-More CNC (proprietary multi-spindle CNC) |
| Machine Weight | Approx. 12,000 kg |
| Manufacturer | Star |
| Model | SR-32J |
| Spindle Bore | 78.74 mm |
| Phase Type | Three-phase |
Specifications sourced from machinio.com — verified 2026-03-28
Strengths & Limitations
Strengths
- CNC cam-less design enables fast job changeover compared to legacy mechanical multi-spindles
- 6-spindle simultaneous cutting delivers seconds-per-part cycle times for high-volume production
- 20mm capacity covers connector bodies, miniature hydraulics, medical hardware, and automotive small parts
- Higher spindle speed (8,000 rpm) than the Sigma 32 supports smaller diameter high-speed cutting
- Tornos global service and support network — well-established in European and North American precision shops
Limitations
- Capital cost requires high-volume, sustained production runs to justify investment
- Multi-spindle programming expertise is scarce — staffing trained operators is a real constraint
- 20mm capacity limits the machine to smaller part families; larger-diameter jobs require the Sigma 32
- Machine mass and foundation requirements make relocation difficult once installed
Best For
Frequently Asked Questions
01
The primary difference is bar capacity: the Sigma 20 handles bar stock up to 20mm diameter while the Sigma 32 extends to 32mm. The Sigma 20 also runs at higher maximum spindle speed (8,000 rpm vs 6,000 rpm), which benefits the smaller-diameter, higher-speed cutting applications in its size range. Both share the CNC cam-less C-More control architecture.
02
Tornos C-More is a proprietary multi-spindle CNC purpose-built for simultaneous multi-position machining. Rather than programming each axis independently, C-More allows programmers to define operations at each spindle position and then synchronize them to optimize the overall drum cycle. Graphical simulation shows all positions cutting simultaneously, allowing identification of bottleneck positions before first production.
03
Yes. The Sigma 20 is well-established in medical device manufacturing for high-volume production of bone screws, spinal implant fasteners, and small instrument components. The machine's precision heritage (built to Swiss standards), C-More control repeatability, and compatibility with stainless steel and titanium machining make it a recognized platform in the medical contract manufacturing sector.
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