screw technology - backlash

It's a common knowledge that a good and precise machinery must be one that has as little backlash as possible. Backlash is any non-movement that occurs during axis reversals. For example, the X axis is commanded to move 10mm to the positive direction. Immediately after this X movement, the X axis is commanded to move 10mm to the negative direction. If any backlash exists in the X axis, then it will not immediately start moving in the negative direction, and the motion departure will not be precisely 1 inch.

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screw technology - ballscrew vs. leadscrew

Ballscrews and lead screws are the workhorses of today's motion-centric automation environment. In that light, making the correct choice for an application is extremely important.

Ballscrew technology allows balls to roll between the screw shaft and the nut to achieve high efficiency, usually above 90%, depending on lead angle. Its required driving torque is only one third of a conventional lead screw. As a result, ballscrews are capable of converting rotational motion to straight motion and vice versa. This screw type is suitable when smooth motion, efficiency, accuracy, and precision are a priority. The rolling elements eliminate sliding friction, so smaller motors can be used to drive ballscrews. And, because rolling motion is easier to control, accuracy and precision are also easier.

Lead screws are different in that there are no recirculating elements, and they are often used for simple transfer applications when speed, accuracy, and precision, are not as critical as rigidity and the load. On a positive note, more surface contact of the threads can make for a higher load rating of the nut over ballscrews. However, their metal-to-metal contact and high friction makes lead screws more suited to applications that do not require prolonged continuous movement or high speed.
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