Common Inspection Methods for High Speed Steel Rolls

The commonly used methods for detecting high-speed steel rollers include:
1、 Eddy current automatic inspection
Advantages: It belongs to automatic flaw detection and has an automatic recording system, which can accurately determine the axial position of defects on the roller. The detection sensitivity is high, and it can detect some small surface or near surface defects, which is incomparable to other detection methods such as ultrasound.
Disadvantage: Unable to determine the type, shape, and depth of cracks, and unable to determine the true equivalent of defects. Sometimes it is influenced by various factors, such as the distance between the probe coil and the tested drum, the material, size, shape, conductivity, permeability, defect type, etc. of the drum. Regular calibration of eddy current sensitivity and assistance with other detection methods are important means to ensure the effectiveness of testing.
2、 Rolling eddy current testing
In recent years, the automatic ultrasonic testing system for coil materials has been popularized and combined with eddy current testing.
Advantages: It has good penetration and directionality, making it easy to detect defects inside and outside the roller. Capable of locating, quantifying, and limiting defects. For defects such as cracks and internal layering, the sound beam is perpendicular to the defect to obtain high reflection echoes. It is easy to detect various defects and determine the nature of defects using waveform conversion and frequency conversion.
Disadvantages: Good coupling agents are required; Require well-trained and experienced operators; Operators have a broad understanding of defects
The ultrasonic testing method can be manual or automatic. Although manual ultrasonic testing methods can be used to detect surface and subsurface defects, as well as internal defects and voids, the emergence of automated roller detection systems means that manual ultrasonic testing is now mainly used to detect internal defects, as well as to detect the crack depth at the fillet of the roller neck. Most rolling workshops use pulse echo ultrasonic flaw detectors with fluorescent screen display for manual inspection.
Ultrasound is usually used to determine the integrity of the roll. Most roller manufacturers conduct this type of inspection as part of the production process, but based on experience, it is necessary for users to conduct ultrasonic testing of internal defects in the rollers.
3、 Magnetic particle inspection
Magnetic particle inspection technology is mainly used to detect cracks on the surface of roller bodies and fatigue cracks in the roller neck area, excessive cyclic loads, or subsequent normal corrosion.
Advantages: Convenient and fast, capable of detecting metal surface opening defects and subcutaneous defects, and able to clearly display the shape of defects. Disadvantage: The defect cannot be quantified. In addition, the cleanliness and smoothness of the roller surface can also affect the results of magnetic particle inspection.
4、 Penetrant dye inspection
Due to its simple use, penetrant dye testing is widely used for detecting surface cracks on rolling rolls.
Advantages: No power supply required; It can detect complex shapes and indicate the shape and size of defects; Can display fewer but more dense defects; Can detect ferrous and non-ferrous metals.
Disadvantage: Unable to detect subsurface defects; The surface is clean, oil-free, and dry.
Precautions for testing defects in high-speed steel rollers:
1. The bulk inspection of the surface quality of high-speed steel rollers mainly relies on automatic eddy current testing of grinding machines, supplemented by other inspection methods.
2. In eddy current testing, when the signal is abnormal, the authenticity and location of defects are the main tasks for grinder operators and flaw detection personnel to judge.
3. If the amplitude of the wave far exceeds the set sensitivity value, a visual inspection is required. In this case, the defect is visible to the naked eye. If there are no visible defects, the area shall be subjected to secondary flaw detection and re inspection after demagnetization treatment based on the positions displayed on the X-axis and Y-axis.
4. If there are abnormal signals, magnetic particle or infiltration and ultrasonic assisted testing shall be conducted in this area to distinguish the authenticity of defects, and the defects shall be quantified through ultrasound.
5. Compared with several auxiliary methods, magnetic particle testing combined with ultrasonic testing is more practical, reliable, and fast.
The above is the commonly used detection methods for high-speed steel rollers. If you are interested in learning more, please feel free to contact us!