Accuracy maintained under misalignment

Though other one-piece couplings outwardly resemble the Reli-a-Flex, but the vital difference is the patented slot design. That on the Reli-a-Flex maintains a constant pivot length which minimises stress variations. On the Reli-a-Flex, the pivot points travel back and forward without changing the centrepiece angle, resulting in uniform stress levels and accurate angular rotation. Similar-looking couplings on the market can actually have a slot pattern where the pivot points move in and out, and the centrepiece angle varies. This causes stress variations and less uniform rotation.

In tests performed by Reliance on typical applications, the bi-directional error produced by a Reli-a-Flex coupling used to drive a 3600 line encoder is claimed to be a quarter that produced by a four-beam spiral coupling. When used to drive a 6.35mm lead leadscrew, the bi-directional error from the Reli-a-Flex is claimed to be a sixth that of the four-beam spiral.

The original range includes outside diameters from 13 to 40mm and the additional micro sizes now available are 6, 8 and 10mm. These couplings retain all the advantages of the original patented design, and are aimed at miniature motion control applications, such as those seen in the printing, medical and scientific instrument markets. Reli-a-Flex has been tested for 50,000,000 cycles at its rated torque and 80% maximum offset.

More accuracy

With the latest advances in digital optical scanning speed, professional flatbed scanner manufacturers are requiring more accuracy from their drive systems. One European manufacturer of drum and flatbed scanners, image setting and integrated media processor products is using Reli-a-Flex couplings in all its flatbed products. With XY technology, speeds of up to 50 scans per hour and resolutions of up to 5400dpi, the accuracy and reliability of the Reli-a-Flex coupling has eliminated errors caused by slight variations in the speed of the CCD element when trying to capture high resolution images. These errors manifest themselves as a colour registration defect, which resulted in an unacceptable banding effect across the image. Although these errors were small (typically 3.0 microns) they could easily be detected by the naked eye. The cause of these errors was identified as the flatbed drive system. Introduction of a Reli-a-Flex coupling manufactured from low inertia Grade 7075-T6 aluminium helped bring these registration defects under control.

During development of a new generation of micro plate analysis machines, engineers at a leading European scientific instrument supplier selected the Reli-a-Flex coupling as a critical part of the drive and positioning system. In line with the industry trend to achieve more accurate, faster machines, this particular machine features handling plate formats from 96 up to 1536 wells, and the capability to read 1536 wells in less than one minute. Analytical techniques include fluorescence intensity, absorption fluorescence, polarised time delayed fluorescence, and glow luminescence.

Accuracy and speed of operation of the transport mechanism are critical, this meant that the correct selection of coupling was essential. The Reli-a-Flex coupling was chosen as the link between the drive motor and the transport mechanism. High torsional stiffness, low inertia and accurate transmission of motion between the motor and the leadscrew drive were provided by a size 16 Reli-a-Flex coupling.

Available as a standard catalogue product and manufactured from aircraft grade aluminium alloy, Reli-a-Flex flexible shaft couplings can also be selected by visiting the online store where a custom coupling can be created to match specific design applications. The coupling selector enables the designers to create their own unique Reli-a-Flex coupling with exact specifications for the application in hand, rather than using a coupling with a similar specification which could potentially compromise the design. A selected "preferred range" is available ex-stock on short lead times.