HARD SPOT INSPECTION TROLLEY - English -
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Operating and Maintenance Instructions
adaptaed from: https://app.box.com/s/c6qfgtuhfg1yd2ottrfum98x8jmg7rn3
| Hard spot inspection trolley • PLAMAT-M •
18201 |
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| Operating and
Maintenance Instructions • V2.0 |
Fundamental principles
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Usually materials with high mechanical hardness have also a high magnetic hardness, that
means these materials need a high magnetic energy for magnetization and in reverse soft
materials can be magnetized with few energy. Figure 2 shows the hysteresis curve of a soft
and a hard material. The shape of the hysteresis curve of the soft material narrow and high
and the one of hard materials is wide and low. A characteristic parameter of the hysteresis
loop is the coercivity HC, which is smaller for soft materials than for hard material.
Figure 2: Hysteresis for magnetic hard (Martensitic) and soft (Ferrite) materials
The precise method for measuring a hysteresis curve makes
high demands on the measurement set up and the sample geometry. So the
shape of the sample must be a long rod which must be magnetized very homogenously with very low frequencies. The measurement of the magnetization is taken with a coil enveloping the rod shaped sample. As this measurement set-up is not useful for practical applications, the 3MA-X8 has been developed to measure the hysteresis behavior indirectly by using sensors which can be put onto the surface of nearly any sample geometry.
The following three testing methodologies are used for the trolley:
- Eddy current impedance analysis
- Incremental permeability analysis
- Upper harmonics analysis
Figure 3: Methodologies applied for material characterization
From these methods testing statistics are derived which correlate with material properties. They satisfy special requirements for recording magnetic hysteresis (e.g., stepwise increasing H, sample geometry, …) and offer a real-time characterization of heavy plates under harsh conditions in steel mills.
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