What are the reasons for the poor accuracy of vertical machining centers?

A machining center with a spindle axis perpendicular to the worktable refers to a machining center that can be used for processing complex parts such as plates, disks, molds, and small shells. However, batch processing of vertical machining centers can achieve high consistency in workpiece dimensions, which is relatively difficult to operate manually. Even if a certain error value is allowed, assuming that improper reference data settings or operational errors can indirectly affect the machining accuracy of workpieces, what are the reasons for the poor accuracy of vertical machining centers? Let's take a brief look below:

1. Due to high cutting speed, inappropriate cutting fluid, excessive wear of the reamer, excessive main rake angle or clearance of the reamer, etc., the machining roughness of the vertical machining center can be high.

Due to the many factors that cause high roughness, it is difficult to solve the problem. It is possible to reduce the cutting speed, select cutting fluid based on the machining material, reduce the reaming allowance and improve the accuracy and quality of the bottom hole position before reaming, increase the reaming allowance, increase the space of the chip groove or use a reamer with a blade inclination angle to ensure smooth chip removal, regularly replace the reamer, and choose the appropriate tool.

2. Due to the wear of the guide sleeve on the vertical machining center, or the distance between the lower end of the guide sleeve and the workpiece being too far, the length of the guide sleeve being short, or poor accuracy, the accuracy of the hinge hole position is poor.

Regularly inspect and replace the guide sleeve, lengthen the guide sleeve, strengthen the fit accuracy between the guide sleeve and the reamer clearance, and adjust the spindle bearing clearance in a timely manner.

3. Loose spindle bearings, sand holes or air holes on the hole surface, or excessive rigidity of the reamer can cause the inner hole of the vertical machining center to be non-circular.

The problem can be solved by using rigid connections for installation of reamers, selecting qualified reamers, controlling the hole position tolerance of the pre-processing process, using reamers with unequal tooth pitch, selecting qualified blanks, and regularly adjusting the spindle clearance.

4. The cutting speed of the vertical machining center is too high, the feed rate is inappropriate or the machining allowance is too large, or the aperture of the vertical machining center itself gradually increases due to it.

It can be handled according to the actual situation by appropriately reducing the outer diameter of the reamer, lowering the cutting speed, reducing the main deviation angle, selecting cutting fluid with good cooling performance, adjusting or replacing the spindle bearing, or replacing the entire spindle, all of which can effectively solve the problem of increased aperture.