How to determine the precision of a vertical lathe?

I. Core Items of Precision Testing

1. Geometric Accuracy: Checking the straightness, parallelism, and perpendicularity of key components such as guideways and spindles.

2. Positioning Accuracy and Repeatability: Evaluating the accuracy and consistency of each coordinate axis moving to a specified position under the control of the CNC system.

3. Spindle Accuracy: Detecting the radial runout and axial movement of the spindle to ensure rotational stability.

4. Working Accuracy (Cutting Accuracy): Measuring the dimensions, shape, and surface roughness of standard test pieces to comprehensively reflect the actual accuracy of the machine tool under cutting conditions.

II. Commonly Used Testing Tools and Methods

1. Laser Interferometer: High-precision measurement of linear motion positioning accuracy.

2. Level, Dial Indicator, Straight Edge: Detecting the geometric tolerances (such as perpendicularity and parallelism) of guideways and spindles.

3. Spindle Check Bar: A specialized inspection tool for measuring the radial runout and axial movement of the spindle.

4. Standard Specimens and Coordinate Measuring Machine: After machining the specimens, measure their geometric parameters using precision instruments such as a coordinate measuring machine.

III. Industry Standards and Specifications

1. General Standards: Such as GB/T 17421 series, ISO 230-1, etc.

2. Specialized Standards: Such as "CNC Precision Single-Column Vertical Lathe - Part 1: Accuracy Inspection" (T/CMTBA 1005.1-2019), applicable to machine tools with a maximum machining diameter of 1000mm to 2500mm.

IV. Recommended Testing Process

1. Installation and Commissioning Stage: Conduct comprehensive geometric accuracy, positioning accuracy, and spindle accuracy tests.

2. Daily Use: Regularly perform working accuracy tests (such as machining standard specimens) to monitor accuracy stability.

3. When Accuracy is Abnormal: Combine geometric accuracy and positioning accuracy tests to troubleshoot the root cause of the problem.

V. Precision Grade Reference

1. Standard Grade: Roundness approximately 0.02mm, Cylindricity approximately 0.01mm/150mm, Flatness approximately 0.03mm.

2. Precision Grade: Higher precision specifications; tolerance values ​​need to be determined according to specific standards (such as T/CMTBA 1005.1).