How to control the accuracy of CNC milling machines

The accuracy of CNC machining parts depends on many factors, including part design, tool selection, tool path programming, fixture fixation, and so on. Different industries have different requirements for the accuracy of parts, such as medical, aerospace, automotive, chemical, and other industries. Of course, there are many other industries that also have high requirements for the accuracy of parts, and some industries that do not have such high requirements for the accuracy of parts pay more attention to the stability of the accuracy of parts, that is, to minimize the dimensional differences between parts.


How does a CNC machining factory ensure the accuracy of parts?


1. CNC milling machine accuracy: 3 measurements


The overall accuracy of a milling machine is determined by three different measurements: positional accuracy, repeatability accuracy, and tolerance.


2. Position accuracy


The positional accuracy is equal to the difference between the distance between the specified points on the part and the actual measured distance of these points after milling. For CNC milling machines, accuracy depends on the ability to follow the programming path. The processing plant determines the positional accuracy of the milling machine by repeatedly measuring and calculating the statistical average of the deviations.


3. Repetition accuracy


Define the accuracy of the milling machine by accurately repeating the same commands in order to achieve the same results one after another. Similar to accuracy, the accuracy of a CNC milling machine is calculated through multiple measurements when setting the cutting path. The measure of accuracy is the repeatability of cutting the same precise path, resulting in repeated and accurate replication of parts.


4. Tolerances


The goal of CNC milling machines is to keep them within specified tolerances by repeatedly maintaining high positioning accuracy. For example, imagine shooting an arrow at a target. The distance between the arrow and the bull's eye measures accuracy.


How to judge the accuracy of CNC machining


In order to maintain the required accuracy of parts, good machining plants prioritize the following in their processes and procedures:


1. Working environment


Accuracy depends on the working environment that provides stable conditions, such as temperature and humidity.


2. Device Status


The accuracy of CNC milling machines requires continuous preventive maintenance to maintain all equipment in perfect working condition.


3. Machine Calibration


The machine periodically recalibrates all precision milling machines to maintain factory settings.


4. Tool monitoring


Monitor cutting tools, maintain and replace them based on their status.


5. Fixture


In order to minimize the impact of vibration, it is necessary to use suitable clamps to secure the workpiece.


6. Mechanic experience


Experienced mechanics are more likely to understand the subtle differences that lead to the manufacture of precise parts.


7. Programming


Experienced manufacturing engineers understand how to effectively manufacture accurate CNC milling machine parts using different tools in different methods and speeds.