precautionary methods of measurement errors on the ultrasonic thickness gauge

Ultra-thin material

When it is measuring ultra-thin materials, sometimes an erroneous result called "double refraction" occurs. The result that the display reading is twice the actual thickness. Another error result is called "pulse envelope, loop jump." The result is that the measuring value is greater than the actual thickness. To prevent such errors, the measurement check should be repeated when is measuring the critical thin material.

Rust spots, corrosion pits
The rust pits on the other surface of the material to be tested will cause the reading change irregularly. In extreme cases, there is no reading, and small rust spots are sometimes difficult to find. When pits are found or suspected, the measurement of this area is very careful, and the probe of coating thickness measurement gauge can be selected at the different angles for multiple tests.

Material identification error
When the instrument is calibrated with one material and another material tested, an erroneous result will occur and care should be taken to select the correct speed of sound.

Probe wear
The surface of the probe is made of acrylic resin. The long-term use will increase the roughness, resulting in the decreasing of sensitivity. In the case where the user determines the error caused by the cause, the surface of the probe can be polished with a small amount of sandpaper or whetstone to smooth and ensure the parallelism. If it is still unstable, you need to replace the probe.
 
Laminated material
It is impossible to measure the uncoupled laminated material because the ultrasonic waves cannot penetrate the uncoupled space. Since ultrasonic waves cannot propagate at a uniform velocity in the composite material, instruments that measure thickness using the ultrasonic reflection principle are not suitable for measuring laminated materials and composite materials.

Effect of metal surface oxide layer
Some metals can produce a dense oxide layer on the surface, such as aluminum. This layer is tightly bonded to the substrate without obvious interface, but the propagation speed of ultrasonic waves in these two substances is different, which will cause errors. The thickness of the oxide layer varies greatly. Please pay attention to the user's use. You can select a piece of the same material to be sampled with a micrometer or caliper to calibrate the ultrasonic thickness measurement equipment.

Abnormal thickness reading
The operator should have the ability to discern abnormal readings, usually rust spots, corrosion pits, and internal defects in the material being tested will cause anomalous readings.

It is important to select the right type of couplant, and low viscosi

ty couplants (such as randomly configured couplants, light motor oils, etc.) which are suitable when using smooth material surfaces. When used on rough surfaces, or vertical and top surfaces, higher viscosity couplants (such as glycerin cream, butter, grease, etc.) can be used.

Cleaning of the test block
When using a random test block to test the paint thickness measurement gauge, it is necessary to apply a coupling agent, so please pay attention to rust prevention. Wipe the random test block after use. Do not get the Chinese liquid when the temperature is high. If it is not used for a long time, a small amount of grease should be applied to the surface of the random test block to prevent rust. When it is used again, the grease can be wiped clean and normal work can be performed.

Case cleaning
Alcohol, dilution, etc.they have a corrosive effect on the casing (especially in the window), so when it is cleaning, gently wipe with a small amount of water.

Probe protection
The surface of the probe is made of acrylic resin, which is sensitive to the redrawing of rough surfaces, so it should be lightly pressed during use. When measuring rough surfaces, minimize the scratching of the probe on the work surface.

When it is measuring at room temperature, the surface of the object to be tested should not exceed 60 ° C, otherwise the probe can no longer be used.Dust adhesion will cause the probe wire to age and break, and the dirt on the cable should be removed after use.