14 Jul 2026
The Star SR-20RIV Type E offers simultaneous 4-axis control, programmable B-axis, guide bush flexibility, and up to 41 tools in a single setup. One machine, remarkable capability.
But what does all of that really mean in practice?
If you are an OEM and looking for an AS9100-established supplier and want to understand what this class of machine could do for your components, you’re in the right place.
Here’s a thorough look at the Star SR-20RIV Type E and why R E Thompson has added it to our Andover facility.
What is the Star SR-20RIV Type E?
The SR-20RIV Type E is a CNC sliding head lathe, also known as a Swiss-type automatic lathe, manufactured by Star Micronics. The Japanese precision machine tool maker’s SR-20RIV platform has accumulated sales of over 2,400 machines since its 2012 launch.
The Type E is the latest evolution of that series, developed to serve a broader range of industries and machining requirements than its predecessors.
At its heart, a sliding head lathe works by moving the bar stock through a guide bush rather than moving the cutting tool along a fixed workpiece. This approach provides exceptional support close to the cutting point, which dramatically reduces deflection, enabling tight tolerances to be held on long, slender components that would challenge a conventional fixed-head turning centre.
The Type E extends this proven platform with a programmable B-axis tool post, simultaneous 4-axis control, and a switchable guide-bush/non-guide-bush configuration.
The result is a machine capable of handling genuinely complex, multi-feature components within a single setup.
The engineering behind the Type E
The B-axis tool post
The defining feature of the SR-20RIV Type E is its programmable B-axis. Unlike the Type A, where the power-driven tool unit angle must be adjusted, the Type E allows the cutting angle to be set and changed via a CNC programme.
This enables compound-angle machining, 3D milling, and the generation of complex features that would otherwise require secondary operations or a more elaborate setup.
It’s a distinction that matters. Manually adjusting a tool angle mid-run requires operator intervention and introduces setup time.
Programmable control means those angles are part of the part programme itself, repeatable to the exact same standard every time. The B-axis tool post accommodates six tools, and the machine carries up to 41 tools in total across its 27-position station.
Giving you enough flexibility for genuinely complex, multi-feature components.
The cross guide structure
High tool post rigidity is often taken for granted, but it has a direct bearing on surface finish, dimensional accuracy, and tool life. The SR-20RVI Type E employs Star’s proprietary uniform load cross guide structure on the gang-type tool post.
In a conventional arrangement, the X and Y slide tables are each supported by four linear guide bearings, for a total of eight. The cross-guide structure positions all eight bearings symmetrically around the guide bush, where the load is generated during cutting.
By distributing cutting forces evenly across all eight bearings, no single bearing carries a disproportionate share of the load. The practical result is sustained rigidity over long production runs, consistent accuracy, and prolonged service life of the guide components.
For manufacturers running high volumes of precision components, this isn’t a marginal benefit; it’s the difference between a machine that holds tolerance at hour one and one that holds it at hour five hundred.
Guide bush/non-guide bush switching
One of the more commercially useful features of the Type E is its ability to switch between guide-bush and non-guide-bush configurations without requiring separate machining.
In guide-bush mode, the classic Swiss-type setup, the material is supported very close to the cutting point, allowing long, slender parts to be machined with minimal deflection. This is the configuration of choice for components where the length-to-diameter ratio would otherwise compromise accuracy.
In non-guide bush mode, the guide bush is removed. This is less suited to long, thin parts, but for shorter components it offers a significant material saving.
The remnant bar left over at the end of each bar is reduced by approximately one-third compared to guide bush operation. On high-volume runs using expensive material, that reduction in waste can represent a meaningful cost saving.
Having both options available in a single machine gives production planners the flexibility to optimise for the component at hand rather than accepting a compromise.
Spindle performance
Both the main and sub-spindles on the Type E run to 10,000 rpm, with 3.7kW of power available. The sub-spindle carries its own independent 8-station platen with Y2-axis control, allowing power-driven tools to be used in either cross or front-facing orientations from any station.
Overlapping main and sub-spindle operations, machining the front and back of a component simultaneously, is central to achieving short cycle times on complex parts, and the Type E is well configured for it.
The maximum machining diameter is 20mm as standard, with a 22.2 mm option available in guide bush mode; the Z1 stroke reaches 205mm.
What can it produce?
The SR-20RIV Type E is aimed squarely at precision components in the sub-20mm diameter range where complexity, accuracy, and cycle time all matter simultaneously.
The industries that tend to need exactly that combination include:
Aerospace & defence
Hydraulic connectors, actuator components, fasteners, and precision pins that require tight tolerances across multiple features. The single-setup capability is particularly valuable here, where material traceability and dimensional integrity across operations are non-negotiable.
Automotive & Motorsport
Fuel system components, sensor housings, valve parts, and transmission components. High volume, consistent quality, and short cycle times are the priorities, and the Type E’s overlapping spindle capabilities and extensive tooling capacity are designed with exactly that in mind.
Medical Devices
Bone screws, implant components, cannulas, and surgical instrument parts, where surface finish and dimensional consistency are as important as the geometry itself. The machine’s rigidity and ability to maintain accuracy over long production runs are well suited to these requirements.
Fluid power & industrial
Precision fittings, valve bodies, and hydraulic components that combine turned diameters with cross-drilled features and milled faces. The B-axis and simultaneous 4-axis capability handle compound geometry without the need for subsequent operations.
How R E Thompson uses the SR-20RIV Type E
At R E Thompson, we’ve been delivering precision-engineered components for over 78 years. Our facility in Andover, Hampshire, serves customers across aerospace, defence, medical, and industrial sectors where getting it right the first time, every time, is the baseline expectation.
The addition of the Star SR-20RIV Type E to our sliding head turning capability reflects a straightforward principle. The right machine for the component, not a compromise between machines.
When components in the sub-20mm range demand complex geometry, tight tolerances, and short cycle times, the Type E is the answer.
Practically speaking, this means that work that previously occupied other machines on our floor or required additional operations can now be completed on a single platform. That frees up capacity across our wider machining capability and allows us to take on more complex sliding-head work without the setup overhead that multi-operation production demands.
It also means shorter lead times for our customers on components that fit this profile.
Training was completed at installation, and production work was lined up and ready to run from day one. That’s not unusual when a machine integrates into an experienced team’s workflow; it contributes quickly.
Our engineers are already working with customers to identify components that could benefit from the Type E’s capabilities and, in some cases, making small design suggestions that unlock better cycle times without affecting function.
Is the SR-20RIV Type E the right machine for your components?
If you’re an engineer or buyer specifying components in the precision sliding head space, the honest answer is that it depends on your geometry.
For sub-20mm-diameter components that combine turned features with cross-drilling, milling, angular faces, or compound geometry, produced in volume, Type E’s combination of B-axis control, extensive tooling capacity, and switching flexibility makes a strong case.
The cross guide structure means you’re not trading rigidity for versatility.
If your components are simply turned parts, straightforward and without compound features, a less complex machine may serve you better and more economically.
If you’re not sure, that’s entirely fine. Part of what R E Thompson does is look at component drawings and work out the most efficient manufacturing route. We’re not tied to a single approach, and we don’t have a reason to overcomplicate production. If the SR-20RIV Type E is the right tool, we’ll tell you why.
If it isn’t, we’ll tell you that too.
Investing in capability for the long term
The SR-20RIV platform has over 2,400 machines in service globally and has been in continuous production since 2012. The Type E is an evolution, not a departure; it improves on the platform customers already trust, adding B-axis programmability and a cross-guide structure to a machine with a long record of reliability in demanding production environments.
For R E Thompson, investing in this machine is part of a broader commitment to keeping our manufacturing capability ahead of our customers’ requirements. We’ve been doing that for over 75 years, and it’s not a strategy we’re changing.
If you have components that would benefit from sliding head turning, whether you know exactly what you need or you’re still working it out, we’re here to help.
Get in touch with our team to discuss your precision engineering requirements.
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