How to determine the machining accuracy of a CNC machining center?

　　It is estimated that there will be machining centers in everyone's workshop,and the accuracy of a machining center is crucial because the accuracy of the machining center affects the processing quality.Therefore,regarding the accuracy of the machining center,mechanical processing professionals have been researching methods to minimize errors as much as possible.So how to determine the accuracy of a machining center?Let's talk about four aspects below.

　　1.Positioning of vertical machining center specimens:

　　The test piece should be located in the middle of the X stroke and placed along the Y and Z axes at an appropriate position suitable for the positioning of the test piece and fixture,as well as the length of the tool.When there are special requirements for the positioning position of the test piece,it should be specified in the agreement between the manufacturer and the user.

　　2.Fixation of the test piece:

　　The test piece should be easily installed on a dedicated fixture to achieve maximum stability of the cutting tool and fixture.The installation surface of the fixture and test piece should be straight.The parallelism between the mounting surface of the test piece and the clamping surface of the fixture should be checked.Suitable clamping methods should be used to ensure that the tool can penetrate and machine the entire length of the center hole.It is recommended to use countersunk screws to fix the specimen to avoid interference between the tool and the screw,or other equivalent methods can be used.The total height of the specimen depends on the chosen fixing method.

　　3.Material,cutting tool and cutting parameters of the test piece:

　　The material,cutting tool,and cutting parameters of the test piece shall be selected according to the agreement between the manufacturer and the user,and shall be recorded.The recommended cutting parameters are as follows:

　　1)Cutting speed:about 50m/min for cast iron parts;Aluminum parts are approximately 300m/min

　　2)Feed rate:approximately(0.05-0.10)mm/tooth.

　　3)Cutting depth:All milling processes should have a radial cutting depth of 0.2mm

　　4.Size of the test piece:

　　If the specimen has been cut several times,resulting in a decrease in overall dimensions and an increase in aperture,it is recommended to use the final contour machining specimen size that is consistent with the specifications in this standard when used for acceptance inspection,in order to accurately reflect the cutting accuracy of the machining center.The test piece can be repeatedly used in cutting tests,and its specifications should be kept within 10%of the characteristic dimensions given in this standard.When the test piece is reused,a thin layer cutting should be performed before conducting a new precision cutting test to clean all surfaces before conducting the test.

　　Perhaps everyone will encounter another problem when using a machining center,why does the accuracy of the machining center deteriorate when used?Did we buy counterfeit goods?The poor machining accuracy of the parts of the machining center is generally due to the failure to adjust the feed dynamics between the shafts according to the error during installation and adjustment,or the change of the Shaft-driven bicycle transmission chain of the machine tool(such as the change of the lead screw clearance,pitch error,axial displacement,etc.)after wear.It can be resolved by readjusting and modifying the gap compensation amount.

　　When the dynamic tracking error is too large and an alarm is triggered,it can be checked whether the servo motor speed is too high;Whether the position detection component is in good condition;Check if the position feedback cable connector is in good contact;Whether the corresponding analog output latch and gain Potentiometer are in good condition;Whether the corresponding servo drive device is normal.