Aktek AT300 Panduan Pengguna - Halaman 6

Jelajahi secara online atau unduh pdf Panduan Pengguna untuk Alat Ukur Aktek AT300. Aktek AT300 16 halaman. Ultrasonic thickness gauge

energy into the material being measured such that a strong, stable echo is received by the

gauge. Several factors affect the strength of ultrasound as it travels. These are outlined

below:

Initial Signal Strength. The stronger a signal is to begin with, the stronger its return echo

will be. Initial signal strength is largely a factor of the size of the ultrasound emitter in the

transducer. A large emitting area will send more energy into the material being measured

than a small emitting area. Thus, a so-called "1/2 inch" transducer will emit a stronger signal

than a "1/4 inch" transducer.

Absorption and Scattering. As ultrasound travels through any material, it is partly

absorbed. If the material through which the sound travels has any grain structure, the sound

waves will experience scattering. Both of these effects reduce the strength of the waves,

and thus, the gauge's ability to detect the returning echo. Higher frequency ultrasound is

absorbed and scattered more than ultrasound of a lower frequency. While it may seem that

using a lower frequency transducer might be better in every instance, low frequencies are

less directional than high frequencies. Thus, a higher frequency transducer would be a

better choice for detecting the exact location of small pits or flaws in the material being

measured.

Geometry of the transducer. The physical constraints of the measuring environment

sometimes determine a transducer's suitability for a given job. Some transducers may

simply be too large to be used in tightly confined areas. Also, the surface area available for

contacting with the transducer may be limited, requiring the use of a transducer with a small

wearface. Measuring on a curved surface, such as an engine cylinder wall, may require the

use of a transducer with a matching curved wearface.

Temperature of the material. When it is necessary to measure on surfaces that are

exceedingly hot, high temperature transducers must be used. These transducers are built

using special materials and techniques that allow them to withstand high temperatures

without damage. Additionally, care must be taken when performing a "Probe-Zero" or

"Calibration to Known Thickness" with a high temperature transducer.

Selection of the proper transducer is often a matter of tradeoffs between various

characteristics. It may be necessary to experiment with a variety of transducers in order to

find one that works well for a given job.

The transducer is the "business end" of the instrument. It transmits and receives

ultrasonic sound waves that the instrument uses to calculate the thickness of the material

being measured. The transducer connects to the instrument via the attached cable, and two

coaxial connectors. When using transducers, the orientation of the dual coaxial connectors

is not critical: either plug may be fitted to either socket in the instrument.

The transducer must be used correctly in order for the instrument to produce accurate,

reliable measurements. Below is a short description of the transducer, followed by

instructions for its use.

Left figure is a bottom view of a typical transducer. The two semicircles of the wearface