In this issue, we will take the industry-leading Makino five-axis machining center as an example to introduce you to the main factors that need to be considered when choosing a five-axis machining center.
Structure determines equipment performance
The five-axis machining center has a variety of structures. The structural design of the machine tool determines the performance of the equipment on the basis of the machine tool’s rigidity, machining accuracy, stability, operability, and so on.
The following aspects should be considered:
1) The linear axis does not merge and overlap when moving
2) Equipment with short cutting circuit has good rigidity
3) Whether the tilt rotation axis is a DD motor
4) Whether it is 5-axis linkage
5) 5-axis proximity
Makino’s D200Z/D800Z/a500Z series five-axis machining center adopts a “Z” high-rigidity table structure. As shown in the figure below, the table does not need to be supported at both ends, large-diameter tilt bearings, and the center of gravity B of the workpiece is within A. Compared with the traditional single support structure, the bending amount d is extremely small, and the moment arm L is shorter.
This inclined axis structure can achieve high-precision machining comparable to that of a 3-axis machining center. Even if a heavy workpiece is loaded and rotated, the deflection of the table can be controlled to a minimum. At the same time, the high-rigidity bearing and direct drive motor can also achieve high-precision and smooth rotation with less vibration. In addition, there is excellent spatial proximity.
Excellent spatial proximity with tilted shaft structure
Tilt rotation axis accuracy
The machining accuracy of the machine tool is directly affected by the accuracy of the rotation axis. The Makino D800Z machine tool is used to understand the actual impact of the accuracy of the tilt rotation axis on the machining accuracy.
The minimum resolution of the B/C axis of the D800Z machine tool is 0.0001 degrees, which is 0.36″, and the positioning accuracy is ±3″. Through the following calculation diagram, we can know the resulting accuracy error.
Interference avoidance is a problem that cannot be ignored in 5-axis machining. In addition to the software interference check on the computer side, Makino’s 5-axis machining center is equipped with the machine tool online real-time simulation CSG function as standard, which can prevent interference even in manual mode.
Online real-time simulation CSG function, you can check possible tooling errors or tool length setting errors before processing, so as to reduce the emergency stop during operation to a minimum. During operation, the position information is read based on the pre-calibrated and adjusted data, as well as the coordinates and offset values in the CNC control device, and the possibility of interference is predicted. Once the machine is stopped, the status screen can be displayed in real time, and the predicted interference location and axis movement direction can be confirmed.
Rotation center correction
Changes in the rotation center caused by environmental and temperature changes will affect the five-axis machining accuracy. It should be automatically corrected by the probe. The 3-axis/index/5-axis machining accuracy is verified and processed, and the tool connection error is <±4μm.
Use the probe to automatically correct the 5-axis rotation center
3-axis/index/5-axis machining accuracy verification machining
The linkage accuracy of the five-axis machining center is a manifestation of multi-factor results. Take Makino D200Z as an example, and list processing cases to provide a reference for linkage accuracy.
Processing equipment: D200Z
Workpiece material: NAK80 (40HRC)
Workpiece size: 140x140x35mm
Cavity: clear angle R0.22mm, depth 20mm
Processing time: 1H35min/pocket
Knives: 7 handles and 6 types
Linkage accuracy: position accuracy ±2μm, shape accuracy ±3μm
The processing technology of the five-axis machining center determines whether the performance of the equipment can be maximized. For example, the use of special-shaped tools can greatly improve the processing efficiency.
Processing case: efficiency increased by 6 times!
Shape and size: as shown below, depth 30mm, draft angle 2°, clear angle R3mm