No. 47 How the measurable rotation speed is determined by the photoelectric detector?

For those who are engaging in or just starting “measurement”, we will explain as simple as possible why that measurement is necessary and which measurement equipment is used in this column.
Our sales staff will write articles in turn. From a sales perspective different from that of an engineer, we will share useful information.

We live surrounded by various sounds and vibrations. There are various sources of sounds and vibrations and different pitches of sounds (called frequency).
If we can sort out these complexly mixed sound and vibration components by frequency, we may not only understand their magnitude, but also their sources.
Decomposing such complex signals of sound and vibration into frequency components is called frequency analysis, and a measurement equipment called an FFT analyzer is generally used.
Then, in the first place, why do we need to analyze sound and vibration?

First, let’s talk about vibration.
The vibration is one of the important information that shows the state of machine. If an abnormal vibration occurs in a machine, it will not only work properly but also will cause metal fatigue, which may lead to serious accidents in aircrafts and railroads. Therefore, it is necessary to measure vibration in all situations from development and design to manufacturing, quality control, and maintenance.
Further, in vehicles such as automobiles and railroads, excessive vibration may also trigger unpleasant human reactions such as motion sickness. For workers who use tools with strong vibrations, long-term vibrations such as hand hammers and rock drills may affect their bodies. Thus, it is necessary to reduce vibrations as much as possible.
As we see, it is generally less vibrations are better, while there are some practical usages.
For example, when pouring concrete, it can be hardened more firmly by applying vibration before it hardens.
Vibration massage is effective in maintaining the health of bones, tendons and muscles. It is also used in NASA to minimize the bad influence of weightlessness on astronaut bones.
Further, vibrations help to speed up chemical processes. Powdered materials on the production line can be transported by vibrating the belt.
The dentist uses ultrasonic vibration to remove plaque.　 Vibration tools are used in many industrial processes such as concrete chipping, material drilling and cutting, and surface cleaning.

Second, let’s talk about sounds.
Like vibration, we live surrounded by various sounds. Many creatures such as animals and insects, as well as humans, use sound as a means of communication.
Hearing, unlike visual sense, detects sounds from all directions at 360 °, and it is very important function as warning system that detect danger even in the dark or during sleeping.
Sounds are waves that propagate long distances in water, thus they are essential for many sea creatures, researchers conducting seafloor mapping, divers, fishermen and the world's navy. It can be said that sound is also an important judgment factor in medical field as doctors judge the condition of our heart and lungs through a stethoscope.
In the world of music, sound is also known to have psychological and emotional effects.
While sound has many useful and excellent features, if you continue to listen to loud and unpleasant sounds, it will affect you physically and mentally.
Noise is a factor in quality of life and health, especially in densely populated areas. There are mechanical noise, environmental noise (aircraft, automobile noise, living noise, etc.) and living environment noise (conversation music, other noise in buildings, etc.).
It is necessary to measure and evaluate unwanted sounds that interfere with our daily lives, and to find approaches to reduce those sounds.

Nowadays, the demand for high efficiency, high output, light weight and low cost for various industrial products have been increasing more and more. Reducing sound and vibration while achieving the above at the same time are very difficult tasks since they are in conflict with each other.
In facing these difficult tasks, an FFT analyzer is a useful measurement instrument for accurately measuring sound and vibration.
The lineup of FFT analyzers currently available at our company is as follows. Please take a look if you would like.

【O-Solution DS-5000 Sound Vibration Analysis System】
https://www.onosokki.co.jp/English/hp_e/products/keisoku/data/os_ds/ds5000_osolution.htm

【CF-9000 series Portable FFT Analyzer】
https://www.onosokki.co.jp/English/hp_e/products/keisoku/data/cf9000.htm

(TI)

No.1 “Why we measure sound and vibration?”