Examples | Cyclones and risers | Carbon electrodes | Slates | Pre-cast refractory blocks | Cast-iron products for the mining industry | Accessories for the aluminum industry cast-houses
Slates
Use of SonciByteTM for in-process slates quality control
Slates
Slates are commonly used in Europe to cover the houses' roof. They are extracted from the ore by shearing. The major types of defects contained in slates are delamination cracks as well as quartz and pyrite veins.
Slates quality control
Traditionally, slates quality control has always been achieved by visual inspection and with the use of the hammer test. The application of these techniques requires high amount of manpower. More recently, artificial vision techniques have been developed. Although efficient in identifying the presence of surface defects, such techniques do not allow the detection of internal delamination cracks.
Delamination cracs detection with SonicByteTM
The SonicByteTM has been used in a factory for the detection of delamination cracks in slates. The procedure used was consisting to make each slate vibrating under a symmetrical flexural mode using an electric hammer (see Fig. 1). The acoustic signal generated after impact was collected by a microphone located under the slate.
The SonicByteTM was then proceeding to the treatment of the acoustic signal by means of a method allowing to quantify its attenuation and dispersion inside the slate. The attenuation quantification was based on the total number of wavelengths (or acoustic waves) generated by the slate. The dispersion of the signal was quantified from the periods average value (in microseconds) and their standard deviation between the 100th and the 300th generated acoustic wave.
The example of the acoustic signal generated by a slate very slightly damaged by delamination cracks is shown on Figure 2. The case of a highly damaged slate by such cracks is shown on Figure 3. Note that the blue dots on these figures correspond to the choosen waves by SonicByteTM for the determination of the average resonance period in the interval considered.
Fig. 1: View of a slate on a conveyor and the electric hammer.
Fig. 2: Case of a very slightly damaged slate.
Fig. 3: Case of a highly damaged slate.
Following this work, it could have been concluded that SonicByteTM is perfectly suited for quantifying the damage level of slates caused by the presence of delamination cracks.