I. Direct Judgment Basis: Exceeding Standards in Test Data
When flatness error detected by professional instruments exceeds the factory standard, adjustment is necessary. The judgment thresholds for common accuracy levels are as follows:
Ordinary Level Platform: Flatness ≤ 0.15mm/1000mm
Precision Level Platform: Flatness ≤ 0.10mm/1000mm
High-Precision Level Platform: Flatness ≤ 0.05mm/1000mm
If the measured value exceeds the corresponding level standard, or the single-season change compared to the previous test data is > 0.02mm/1000mm, it indicates that the platform is continuously deforming and requires timely intervention.
II. Abnormal Signals in the Production Process (Indirect Judgment)
Even if the regular inspection cycle has not yet arrived, the following process abnormalities indicate that the flatness may be inaccurate:
1. Workpiece Positioning Misalignment
After the fixture or positioning pin is inserted, the workpiece position does not match the design, and repeated corrections cannot reliably reproduce the error.
2. Weld misalignment or uneven gaps: If workpieces from the same batch are welded under the same fixture and exhibit regular misalignment or poor overlap, after ruling out program and fixture issues, platform deformation should be suspected.
3. Difficulty or looseness in fixture insertion/removal: If the locating pins are stuck or wobble noticeably when inserted, it may be due to relative displacement of the hole system caused by platform warping.
4. Increased gaps at the joints of multiple platforms: Significant height differences or misalignments at the joints result in discontinuity in the overall reference surface after assembly.
⚠️ Special reminder: If similar problems occur simultaneously at multiple workstations, prioritize checking whether the main reference platform is deformed.
III. Simple on-site screening methods (no professional equipment required): When high-precision instruments are unavailable, the following methods can be used for quick preliminary judgment:
1. Knife-edge ruler + feeler gauge method: Place a knife-edge ruler against the platform and use a feeler gauge to measure the gap. If the gap is >0.05mm within a 250mm length, it indicates significant local bulges or depressions.
2. Standard Square Measurement: Use a precision square against the side and a feeler gauge to check the verticality. If the gap is >0.1mm within a 200mm height, it indicates the reference surface is tilted.
3. Red Lead Lapping Method: Apply red lead to a standard flat surface and lap it against the working surface. If the contact points are sparse or concentrated at the edges, it indicates poor flatness.
✅ Recommendation: Include these methods in the daily inspection checklist as the first line of defense for preventative maintenance.
IV. Adjustment Needs Triggered by Environmental and Usage Factors
The following situations require proactive retesting and adjustment even if no abnormalities are found:
Platform experiencing a concentrated period of high-temperature welding operations (e.g., continuous full-load operation for several days);
Impact from heavy objects or improper hoisting causing localized stress on the platform;
Floor repairs or equipment relocation in the workshop, which may affect foundation stability;
Reactivation after long-term disuse, requiring confirmation that the reference condition has been maintained.
📌 Friendly reminder: Conduct a systematic inspection every quarter to establish a "flatness trend file" and realize the transformation from passive maintenance to proactive control.
