I. Electronic Level Method: Quick On-Site Assessment (Suitable for Medium to Large Platforms)
Suitable for daily inspections and quarterly retests. Simple operation, low cost, and accuracy up to ±0.005mm/m.
1. Measurement Principle: Measure the tilt angle at different positions using a level. Calculate the relative height difference between points using the data, and then calculate the flatness error (range method).
2. Operation Procedure:
Clean the table surface, removing oil, welding slag, and other debris.
Arrange points at equal intervals along a "米" (rice) shaped path (two diagonals + four side midlines) (pitch recommended 200~500mm).
Place the level at each point and record the reading (unit: divisions) after the bubble stabilizes.
Convert the number of divisions to the height difference (e.g., sensitivity 0.02mm/m, pitch L=0.3m, then each division corresponds to 0.006mm).
Calculate the difference between the maximum and minimum values among all points; this is the flatness error.
3. Anomaly Judgment Criteria
If the measured value > 0.10mm/1000mm (precision grade), it is judged as an anomaly; A single-season change > 0.02mm/1000mm indicates active internal stress, requiring a warning.
✅ It is recommended to use a digital electronic level, which supports automatic data recording and trend analysis, improving efficiency.
II. Coordinate Measuring Instrument Method: High-Precision Quantitative Detection (Suitable for Acceptance and Verification)
Suitable for scenarios with high precision requirements, such as robotic welding and benchmark confirmation before mass production.
1. Measurement Principle
The system collects the coordinates of multiple points on the table by moving a stylus along the X, Y, and Z axes. The software fits an ideal plane (least square method) and calculates the maximum deviation between the actual surface and the ideal plane.
2. Operational Points
Calibrate the probe before measurement to ensure system accuracy; Distribute at least 50 measurement points evenly on the table (grid method); Avoid interference from environmental vibration and temperature fluctuations; Use professional software (such as PC-DMIS) for data processing.
3. Abnormality Judgment Criteria
Flatness = Maximum Positive Deviation - Maximum Negative Deviation; Any deviation exceeding factory standards (e.g., precision grade > 0.10mm/1000mm) is considered abnormal; A 3D topographic map can be generated, visually displaying protruding, concave, or distorted areas.
📌 Advantages: Precisely locates deformation positions, providing data support for subsequent repairs.
III. Laser Interferometer Method: Ultra-high precision non-contact inspection (suitable for high-precision platform acceptance)
Suitable for high-precision platforms with flatness requirements ≤ 0.05mm/1000mm, such as aerospace and precision mold assembly worktables.
1. Measurement Principle
Utilizing the working surface of an optical flat as an ideal planar reference, a laser beam illuminates the measured surface, forming interference fringes. The curvature of the fringes reflects the flatness error; each closed fringe represents a height difference of λ/2 (approximately 0.3μm under white light).
2. Operating Procedures
Gently place the optical flat onto the cleaned table;
Turn on the laser interferometer and adjust the optical path alignment;
Observe the interference image and analyze the shape and number of fringes;
If the fringes are curved into closed loops, the flatness error = number of interference fringes × λ/2.
3. Anomaly Judgment
If the interference fringes are obviously curved or closed, it indicates the presence of local convexity/concavity;
If the fringes move from the center to the edge → the surface is convex; otherwise, it is concave;
An error value exceeding 0.05mm/1000mm is considered out of tolerance.
⚠️ Note: Only applicable to smooth small flat surfaces (usually <500mm). Large-area inspections need to be performed in segments.
