Differentiation between the precision of positioning when selecting a linear platform and the precision of repeated positioning
time：2017/8/30 click：5764
When our customers select linear Motors, some of them do not know much about the positioning accuracy and the repeated positioning precision. Let Tongmao linear Motors explain the main differences between them for you.
Positioning precision: The accuracy of the actual position achieved by the NC workbench parts at the required end point, the error between the actual position and the ideal position is called the positioning error. The positioning accuracy is the precision that can be achieved by the motion of each moving part of the machine tool under the control of the CNC device. Based on the measured positioning accuracy, we can judge the better workpiece machining precision that can be achieved during automatic machining. Repeated positioning accuracy refers to the consistency of position accuracy obtained by repeatedly running the same program code on a CNC machine tool. Cutting precision is a comprehensive inspection of the machine tool's geometric precision and positioning precision under cutting conditions. The above precision is mainly guaranteed by the CNC system and the machine tool manufacturer in the production and manufacturing process and the machine tool installation and commissioning process.
Repeated positioning accuracy refers to the accuracy of the 7 times of reciprocating motion meter or laser interferometer measured by a machine tool skateboard or a large drag plate within a fixed distance(usually 200-300mm). Repeated positioning accuracy is affected by factors such as servo system characteristics, gap and stiffness of feed system, and friction characteristics. Under normal circumstances, repeated positioning accuracy is an accidental error that is normally distributed, which affects the consistency of processing of a batch of parts. It is a very important precision indicator.
In order to give you a better understanding of the difference between positioning precision and repeated positioning precision, we give you an example:
Positioning accuracy refers to the actual position you reach when your CNC device stops and the location error you require. For example, you require a shaft to go 100 mm. As a result, it actually goes 100.01. The additional 0.01 is the positioning accuracy. Repeated positioning accuracy refers to the error generated by the same location twice in the past. For example, if you ask a shaft to walk 100 mm, he actually walks 100.01, repeats the same action and he walks 99.99. The error between these is 0.02, which is the repeated positioning accuracy.
From the feedback of the linear motor, the calibration accuracy of the grating or magnetic ruler is generally 10-30um, and the repeated positioning accuracy is often as long as there is no problem with the servo PID, and the static PE can easily achieve 1-2 counts., so, Repeated positioning accuracy can generally be relatively easy to achieve a higher degree(within a few um)
Kunshan Tongmao Electronics Co., Ltd., the main products are linear Motors, coil motors and high-precision linear platforms. The company produces linear platforms with high positioning accuracy(after the linear error correction): ± 1 μm(Travel ≤ 200mm); The stable and excellent shaft provides a good smooth motion, and a very small dynamic following error can be obtained by algorithm optimization. The grating feedback system with excellent linear performance can obtain accurate point-to-point position accuracy and submicron level repeatability.
The article is provided by Tongmao Linear Motor. Welcome new and old friends to pay more attention to Tongmao Linear Motor: www.tmemotion.com
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