Product category:
Ballscrews, Linear Guides, Jacks, Dampers
News Release from: SKF UK | Subject: ACS precision rail guides
Edited by the Engineeringtalk Editorial
Team on 21 August 2001
No more 'cage-creep' in precision rail
guides
SKF's new ACS precision rail guides offer consistent positioning of the cage, no need for cage resynchronisation and non-uniform preload, and the elimination of end-stops
Precision rail guides are used in machine components, where a compact design and high levels of accuracy are required Cage-creep is the term given to the action of the cage as it progressively edges along the vee of the guideway
This article was originally published on Engineeringtalk on 1 Aug 2008 at 8.00am (UK)
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Caused by uneven pre-loading and poor rail alignment, the problem tends to be exaggerated, through the effect of gravity, when the guide is mounted vertically.
This problem can lead to unreliable performance or, in more severe cases, premature failure.
When cage-creep occurs, the cage housing, which contains the rolling elements, contacts the end stops of the guideway.
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This causes the elements to begin to skid, rather than roll, thus reducing the effective working operation and lifespan of the rail guide assembly.
SKF's new ACS completely eliminates this problem.
The revolutionary design synchronizes the movement of the cage and roller assembly.
With ACS, the plastic moulding that forms the cage also encloses a small plastic sprocket in its centre.
Corresponding tiny notches are machined in the bottom of each of the guideway vees in order to mesh with the sprocket.
This arrangement creates a low-duty rack and pinion drive as the guideway moves.
A synchronized movement is therefore created that optimises the cage position throughout the stroke of the rail.
The results are consistent positioning of the cage, no need for cage resynchronisation and non-uniform preload.
In addition ACS eliminates the need for end stops, removes the influence on cage creep under extreme loads and facilitates an integrated design, with no influence on boundary dimensions.
ACS has been developed around the SKF modular range of LWRE precision linear guideways to provide the option of direct interchangeability within the three standard cross-section dimensions of 18 x 8 mm, 31 x 15 mm and 44 x 22 mm.
The LWRE Cross Roller Series has already achieved considerable application success.
When compared to a traditional linear rail design that utilises only about 40% of the roller length, the LWRE optimises internal geometry in conjunction with larger rollers to enable a 100 per cent increase in stiffness with a five-fold increase in load carrying capacity, while maintaining the same cross-sectional dimensions.
These higher performance characteristics not only ensure better performance with increased wear resistance, but also provide the designer with the choice to upgrade the specification and capability, or downsize the assembly to a more compact unit. Request a free brochure from SKF UK ...
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