Satellite roller screws
"I need more performance from my ball screw." !
"My hydraulic linear actuation system is a major part of my maintenance schedule"
"My ball screw is failing prematurely due to high duty cycle". !
"I have reached the boundary of performance from my existing ball screw but have no way of increasing its dimensions within the current design" !
These are some of the questions being asked by design engineers or maintenance engineers when coming to ABSSAC in search of linear technical assistance.
Satellite roller screws are high precision linear devices, that faithfully transform rotary movement into a linear movement. By design they are similar to ball screws but with the difference that the ball bearings are replaced by threaded rollers, which are constantly engaged with the threads of the screw. The resulting higher number of contact points within the nut, means that both heavier loads can be accepted, product life is considerably elongated and extremely accurate linear positioning can be achieved.
When you combine these advantages with the capability to supply bespoke designs, opens a whole new world of linear applications to the satellite roller screw product.
Product News update : What we believe to be the smallest satellite roller screw in the world has been supplied for a medical application. Providing a repeatability of 1 micron, the satellite roller screw type RV 3.5 x 1 mm (diameter of the screw 3.5 mm, lead 1 mm). Amazingly the new miniature assembly has the capacity to move over 20'000 times its own weight.
If an application requires a high linear load to be repeatedly moved at speed but you the design constrained by space, the satellite roller screw program is ideal. A roller screw design will always transmit more load than a ball screw nut assembly size for size.
Product News Update : A great example of a high load application successfully mastered by the satellite roller screw was recently examplfied when a standard RV style screw replaced a hydraulic cylinder within an injection moulding machine. Traditionally, hydraulic cylinders initiate the pressure control required within injection moulding machines to ensure mold integrity. Pneumatic systems can not produce the necessary forces and traditional ball screw designs would have to be over-sized to achieve similar forces reliably. During injection molding, plastic material is heated until molten. A motorised auger screw forces the molten material to the end of the injection cylinder. Once enough material has accumulated in front of the screw, the injection process begins with injection pressure provided by hydraulic actuation. However, using hydraulics inevitably requires the use of hydraulic pumps, pipes, seals and control units within the machine, all of which can be bulky in design and expensive to maintain.The satellite roller screw product, delivered the same linear forces necessary for injection, but also has the advantage of being coupled to less expensive and infinitely more adjustable closed loop electric motor drive design.
Satellite roller screws are particularly suitable for applications where high axial loads, high speed, and high feed speeds are requested. Other applications to date have included flight critical aerospace apparatus, medical operating equipment and advanced machine tool operations.
The key product advantages are:
* Heavy axial loads for a small diameter screw
* Nut designs with extreme long life
* High efficiency
* No-backlash standard high stiffness linear precision up to 6 µm / 300 mm
* Can accept a high rotary speed (system RV and BRV without roller return type)
* Extremely small leads can be supplied on large diameter screws (system RVR with roller return design)
Standard sizes include;
| Roller Screws Diameter (mm) |
Leads (mm) | Material | Available in left hand |
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| Steel | Stainless | |||
| 3.5 | 1mm |  |
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| 5 | 1mm - 3mm | |
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| 7 | 1mm - 5mm | |
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| 8 | 0.25mm - 5mm | |
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| 10 | 0.5mm - 5mm | |
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| 12 | 0.5mm - 8mm | |
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| 15 | 2mm - 8mm | |
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| 16 | 0.5mm - 2mm | |
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| 18 | 2mm - 8mm | |
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| 20 | 0.5mm - 10mm | |
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| 21 | 2mm - 10mm | |
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| 23 | 2mm - 10mm | |
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| 25 | 2mm - 8mm | |
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| 27 | 2mm - 10mm | |
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| 30 | 2mm - 30mm | |
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| 32 | 1mm - 2mm | |
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| 36 | 2mm - 20mm | |
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| 39 | 2mm - 25mm | |
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| 44 | 6mm - 30mm | |
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| 48 | 5mm - 30mm | |
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| 51 | 5mm - 25mm | |
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| 60 | 6mm - 42mm | |
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| 63 | 2mm - 4mm | |
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| 64 | 6mm - 36mm | |
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| 70 | 6mm - 24mm | |
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| 75 | 5mm - 30mm | |
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| 80 | 6mm - 36mm | |
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| 92 | 12mm - 24mm | |
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| 100 | 15mm - 30mm | |
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| 120 | 15mm - 30mm | |
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| 135 | 15mm - 30mm | |
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| 150 | 15mm - 30mm | |
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| Available = | |
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Planetary roller screws : It is possible to supply planetary roller screws with smaller leads compared to ball screws. As the lead is a function of the pitch of the planetary roller screw, the lead can be very small (0.5mm and even less). The lead can be chosen and supplied without any geometrical changes of both the screw shaft and the nut body. In a ball screw the lead is limited by the dimension (Outside Diameter) of the bearing ball, which is a standard feature.
As standard, satellite screws can be supplied with outside diameters as small as 10mm and up to 200mm. Leads can be as fine as 0.25mm. The product can be finitely accurate and capable of being adapted into very specialist and demanding linear applications. (specialist satellite roller screw web page)
There are two main satellite roller screw nut designs;
Type - RV AND BRV
When the screw turns, the satellite rollers move as the lead on the screw. In this execution the rollers are in constant contact with the thread of the screw and the thread of the nut. The rollers do not move axially relative to the nut and are not recycled. Due to its design this execution is particularly suitable for applications where high axial loads, high speed, and high feed speeds are requested. RV and BRV may be distinguished from each other by the execution of the screw. The RV screw has a ground thread whereas the BRV has a precision rolled one.
Type - RVR
The RVR execution is designed for small leads and is used where a high positioning precision is required in association with high stiffness and heavier axial loads. As the rollers are recycled after each of their revolutions, this design is not suitable for high speeds.
Nut Styles : (Nuts can be preloaded to obtain zerobacklash)
- Cylindrical
- Cylindrical nut with flange at one end
- Cylindrical nut with flange in centre
- Special/Custom nut designed according to customers request
- Cylindrical nuts x 2 for preloaded purposes
The key product advantages are:
- Heavy axial loads for a small diameter screw
- Nut designs with extreme long life
- High efficiency
- No-backlash standard high stiffness linear precision up to 6 µm / 300 mm
- Can accept a high rotary speed (system RV and BRV without roller return type)
- Extremely small leads can be supplied on large diameter screws (system RVR with roller return design)
If you require further technical information, please do not hesitate to contact our sales engineers who will be more than happy to help you with your selection.