In the field of industrial non-destructive testing, magnetic particle flaw Detector is a key equipment for detecting surface and near-surface defects of ferromagnetic materials, which realizes defect visualization through the principle of magnetic field distortion and magnetic particle aggregation, and is widely used in aerospace, automobile manufacturing, petrochemical and other industries with strict safety performance requirements. According to the differences in usage scenarios and structural design, this type of equipment has formed a diversified classification and precise composition system.
Classification of magnetic particle flaw Detectors
According to different usage conditions, magnetic particle flaw Detectors are mainly divided into three types: fixed, mobile and portable, which have their own emphasis on structural characteristics and application scenarios.
Fixed magnetic particle flaw Detector
The distinctive feature of this type of equipment is that the size and weight of the whole machine are large, and most of them adopt a horizontal structure and need to be installed in a fixed testing station. As a full-featured mainstream model, it can apply circumferential, longitudinal and composite magnetization to the workpiece, and achieve multi-directional defect detection through multi-directional magnetic field coverage. Its magnetization current can be flexibly adjusted, adapting to different materials and sizes of workpieces, and is equipped with AC or DC demagnetization function, which can effectively eliminate the residual magnetism effect of the inspected workpiece. In large-scale production scenarios such as batch inspection of automobile engine crankshafts and quality screening of pressure vessel welds, fixed magnetic particle flaw Detectors have become core equipment with stable performance and efficient testing capabilities.
Mobile magnetic particle flaw Detector
In response to the pain points of difficult handling of large machine parts, mobile magnetic particle flaw Detectors came into being. It has the characteristics of free movement and can directly arrive at the inspection site to carry out operations, such as local inspection of bridge load-bearing structures and large generator set casings. The equipment is equipped with a pair of magnetic cones, which locally magnetize each part of the machine through the electrode contact method, and has a large magnetization current output, which can enhance the magnetic trace display effect in the defect area and ensure that cracks, slag inclusions and other defects can be accurately captured on the complex surface of large workpieces.
Portable magnetic particle flaw Detector
The portable model has the core advantages of small size and light weight, and can be carried by operators, especially suitable for the inspection of special environments such as high-altitude pipelines, underground tunnel steel structures, and field work equipment. Its design focuses on portability, typically powered by rechargeable batteries that can work continuously for more than 6 hours on a single charge. However, due to the limited size, the magnetized magnetic field strength generated by this type of equipment is relatively weak, and the detection range is small, which is generally used for local detection of small parts or supplementary flaw detection of large workpieces.
Structural composition of magnetic particle flaw Detector
The magnetic particle flaw Detector is composed of six core devices: magnetization, demagnetization, workpiece clamping, magnetic particle (magnetic suspension) spraying, observation and lighting, and control, and each device has a clear division of labor and works together. Among them, the magnetization device is the core, which establishes a magnetic field for the workpiece through direct powering, electromagnets and other ways, mostly using 220V/380V AC power supply, and the step-down transformer power supply is the most widely used due to its stability. The demagnetization device eliminates the remagnetization of the workpiece, and the method matches the magnetization, and there are three common types of AC coil, AC step-down and DC demagnetization. The clamping device has both the function of clamping the workpiece and conduction current, and is divided into electric, pneumatic and other types according to the driving force, and the pneumatic type is commonly used in welded parts flaw detection. The spraying device evenly applies magnetic powder or magnetic suspension (kerosene as the carrier liquid, magnetic powder at 10-20 g/liter) on the surface of the workpiece; The illumination device provides a light source for magnetic trace observation, and a black light lamp is required for fluorescent magnetic particle detection (intensity > 800μW/cm² at 380mm); The control device acts as the "center" to coordinate the process of adjusting the current and switching the magnetization mode to ensure the efficiency and safety of the detection.
summary
The magnetic particle flaw Detector is a key equipment for ferromagnetic material defect detection, with three types of fixed, mobile and portable models accurately adapting to different industrial scenarios, and the six core devices work together to ensure the accuracy of detection. It strictly follows industry standards to escort product quality in many fields, and will also upgrade to intelligence and high sensitivity in the future to continue to help industrial quality and safety.
