1.What is the testing principle of a platform + feeler gauge/dial indicator?
Principle: Place the steel plate sample on a horizontal inspection platform. Observe with the naked eye or measure the gap between the steel plate and the platform using a feeler gauge, or measure the height difference at grid points using a dial indicator.
Advantages: Extremely low cost, simple and intuitive operation.
Disadvantages: Completely dependent on manual labor, highly subjective, low efficiency, can only obtain local and discrete data, and cannot comprehensively quantify plate shape defects (such as edge waves, center waves, rib waves, etc.). Suitable for applications with low requirements or for quick and rough judgment.
2.What are the principles, advantages, and disadvantages of electronic flat panel analyzers/plate shape testers?
Principle: This is an integrated testing platform with a dense array of displacement sensors (usually inductive or capacitive) distributed beneath the platform. When a steel plate is laid flat on the platform, the sensor array measures the distance between the lower surface of the steel plate and the ideal plane in real time. Software generates color contour maps, topographic maps, and quantitative data (such as flatness I-Units or waveform peak values).
Advantages:
Full-area measurement: Acquires the three-dimensional topography of the entire steel plate surface in a single measurement.
Objective quantification: Results are presented in data form with good repeatability.
Powerful functionality: The software can analyze various plate shape parameters and generate testing reports.
Disadvantages: High equipment investment; requires sampling for testing; cannot be used for 100% monitoring of continuous production processes.
Typical applications: Steel enterprise laboratories, quality inspection centers, incoming material inspection, new product process verification, etc. This is currently the mainstream and standard equipment for offline testing.
3.What are the principles, advantages, and disadvantages of handheld laser flatness testers?
Principle: Employs laser triangulation or linear laser scanning technology. The instrument moves across the steel plate surface, scanning the surface with a laser line. A camera captures the deformation of the laser line to calculate the surface's undulations.
Advantages: Portable and flexible, suitable for on-site inspection of finished steel coils or large components without the need for cutting and sampling.
Disadvantages: Measurement range and accuracy are generally inferior to fixed electronic plane meters; it is also limited to random sampling.
4.What are the principles, advantages, and disadvantages of laser scanning plate shape analyzers?
Principle: A laser displacement sensor scanning head is installed across the entire width of the strip, scanning at high speed, or a row of fixed multi-point lasers is used. It measures the surface profile (relative height) of the strip under tension. Combined with a tension measurement model, the "relative length difference" of the strip can be calculated, thus accurately characterizing the strip shape (e.g., I-Units).
Advantages:
Real-time and continuous: Dozens of full-width scans can be performed per second, reflecting changes in strip shape in real time.
High precision and high resolution: Accuracy down to the micrometer level, capable of identifying minute waviness and rib waves.
Integration with control systems: Detection data is directly fed back to the control system of the rolling mill or tension leveler, achieving automatic closed-loop control (AFC) of strip shape.
Disadvantages: The system is extremely complex and expensive, with high installation and commissioning requirements, and needs to be integrated into the production line.
5.How to choose?
For final product quality assessment, laboratory analysis, or incoming material inspection: an electronic flat panel analyzer should be selected, as it is currently the most scientific and authoritative tool for offline testing.
For real-time monitoring and automatic control during the production process: an online laser shape analyzer must be installed; this is essential equipment for achieving high-quality shape production.
For limited budgets and only a basic understanding required: the traditional platform method can be used as a supplementary method.