Direct Drive Air Bearing Linear Slideways Enable Ultra Precision Motion


Precision Air Bearing SlidewaysSwindon, UK - A new range of direct drive, linear air bearing slideways from Loadpoint Bearings provides straightness of motion better than 0.1 um in 100 mm of travel, and resolution on position accuracy better than 0.1 um. Developed for use on ultra precision machine tools, the slideways are also highly suited for applications on test or measuring equipment and on machinery used in clean environments.

The direct drive slideways provide a simple, neat and highly effective answer to the requirements for ultra-precise linear motion and positional accuracy. They employ inherently accurate air bearings as machine elements; these units being virtually frictionless at the relatively low surface speeds at which linear slideways are used. In addition, when driven directly by a DC Brushless linear motor, the slideways are completely free from the backlash, mechanical noise and hysteresis associated with other types of bearing and drive. These performance advantages are further complemented by wear-free operation and an indefinite operating life, provided that the slideways are kept clean.

The design of the slideways incorporates a simple dovetail bearing arrangement that ensures good stability against yaw and roll of the carriage, and also provides a low overall height to aid machine integration. Two additional benefits of the design are that that both carriage and rail are manufactured from corrosion resistant stainless steel, to maintain a high structural rigidity; and a three point mounting arrangement is provided, to minimize the distortions arising from attachment to out-of- flat surfaces.

The DC linear drive motor used with the bearings motor is fully optimised for use with precision slideways. It has an ironless U channel construction that minimises magnetic noise and cogging and balances out magnetic forces to avoid parasitic loading of the bearings. As a result, heat generation from the motor and bearings is negligible, under normal duty cycles.

Loadpoint Bearings is producing the new slideways in a range of sizes up to a maximum overall length of 1.0 m. These units can be supplied with or without drives to suit different application requirements. A typical integrated slideway unit and drive is shown in the image provided. The slideway has an overall length 350 mm with a 200 x 200 mm carriage. It has a vertical stiffness of 70 N/um and can support a load of 300 N. The DC drive motor is capable of generating a force of 85 N continuous and 240 N peak.

Posted in Loadpoint News

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