Why do we have to check the accuracy? Because during the operation of the CNC machining center, the problem of accuracy inspection is very important, which will directly affect the standardization of our manufactured parts. Whether a machine tool is good or not depends on its high accuracy. If the accuracy is not high enough, resulting in deviations in the size of the workpiece, then directly affect the precision of your machine.
How do we check the accuracy?
- 1. Positioning the test piece 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 and the length of the tool. When there are special requirements for the location 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 special fixture to achieve maximum stability of the tool and fixture. The mounting 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 shall be checked. Appropriate clamping methods should be used to allow the tool to penetrate and machine the full length of the center hole. It is recommended to use countersunk screws to fix the test piece to avoid interference between the tool and the screw, and other equivalent methods can also be used. The total height of the test piece depends on the fixing method chosen.
- 3. The material of the test piece, the cutter and the cutting parameters The material of the test piece, the cutting tool and the cutting parameters are selected according to the agreement between the manufacturer and the user, and should be recorded. The recommended cutting parameters are as follows:
Cutting speed: about 50m / min for cast iron parts; about 300m / min for aluminum parts.
Feed: about (0.05 ~ 0.10) mm / tooth.
Depth of cut: All milling processes should have a depth of cut of 0.2 mm in the radial direction.
- 4. The size of the test piece. If the test piece is cut several times, the external dimensions decrease, and the aperture increases. When used for acceptance inspection, it is recommended to select the final contour processing test piece size consistent with that specified in this standard in order to faithfully reflect the machine tool Cutting accuracy. The test piece can be used repeatedly in the cutting test, and its specification should be kept within 10% of the characteristic size taxi given in this standard. When the test piece is used again, before the new precision cutting test, a thin layer cutting should be performed to clean all the surfaces.
In many places, people often use accuracy to measure product error. The smaller the error, the larger the limit value will be. This is often the most fancy question in the CNC machining center industry.