CNC machine tools "positioning accuracy" of the smaller better?

Published on 2016-08-25
CNC machine tool accuracy is an important indicator of the performance of the machine, which is an important factor affecting the accuracy of the workpiece. Precision CNC machine tools can be divided into static and dynamic precision accuracy. Static accuracy is without cutting the state test, which comprises two elements geometric accuracy and positioning accuracy of machine tools, machine tools reflects the original accuracy. Dynamic accuracy is achieved by means of the workpiece in the machine under actual conditions of cutting machining accuracy.
I saw the show two similar models of CNC machine tools, "positioning accuracy" of a machine are marked as 0.004mm, another one of "positioning accuracy" marked 0.006mm. From the size of the figures, the smaller the higher the precision is not it? How to understand the accuracy of the machine? 
Both machines "positioning accuracy" is different from the data point of view, we will naturally consider numeric precision is higher. However, the fact that large numbers of precision is likely to be high, the problem is how the accuracy of these two machines is defined. So, when we talk about the accuracy of CNC machine tools, it is important to clarify the definition of different types of machine accuracy criteria and indicators.
CNC machine tools "positioning accuracy" of the smaller better? 
In general, the precision is the tool tip positioning point to the ability to program the target point. However, the measurement of such positioning capability in many ways, more importantly, different countries have different regulations. For example, the German machine tool manufacturers, the general VDI / DCQ3441 standards. When a marked precision CNC machine tools when it is necessary to adopt a standard together marked out. Also a machine, due to the use of different criteria will display different data. 
We are confusing: the same index name in different accuracy standards represents a different meaning, a different index names but have the same meaning. Most CNC machine tools are standard in the machine tool CNC multi-axis target point multi-round measurements, mathematical statistics calculated. The main difference is that: 
1, the target number of points 2, 3 measured the number of rounds, precision index calculation methods and other indicators of 4, from one-way or one-way close to the target point in the near future, I hope that all the machine manufacturer can comply with a unified standard.