FFT Comparator
CF-4700A
For customers who are about to start using frequency spectrum for pass/fail determination
The CF-4700A FFT comparator is an ideal line judgment machine for precise quality inspection of products based on sound and vibration. By incorporating our long-cultivated frequency analysis technology using FFT, it extracts characteristic frequency components that may be problematic and makes pass/fail judgment.
In addition to the frequency component magnitude and waveform shape judgment functions found in the previous model, the CF-4500, this model features a variable component extraction function that extracts the amount of fluctuation in periodically fluctuating sounds and vibrations and makes judgments based on that fluctuation amount. This function judges based on the amount of fluctuation in sounds and vibrations that fluctuate periodically, rather than the frequency level. This function allows for pass/fail judgments regarding noises such as "squeaking" and rattling sounds that occur when motor-driven equipment is in operation. Furthermore, it enables vibration monitoring of bearings using the bandpass filter and envelope functions included in the variable component extraction function, and auditory confirmation by making vibrations audible through the monitoring function (headphone output).
We have added a new judgment assist function that allows you to set the judgment range with simple operations.
The system reads the difference in sound and vibration levels from the respective pass/fail measurement data files and sets the judgment block, making it easy for even customers who are trying to determine pass/fail status using frequency spectra for the first time to set up the blocks.
The block comparator is a function that performs judgments based on blocks (regions) defined by arbitrary frequency and level. It determines whether the peak value, level, etc., of the signal of interest match the set conditions. There are six types of signal judgment methods: level, peak level, peak max, inside max, partial overall, and area coverage. Judgment blocks can be set by dragging while touching the screen on the waveform, or by entering numerical values in the list display.
Related Features
Block comparator function (standard function)
Judgment criterion calculation assist function (standard function)
The shape comparator is a function that determines pass/fail status based on the shape of the waveform. It can set judgment lines to detect subtle changes in the time waveform and differences in the shape of the spectrum. In the time waveform, to prevent false judgments due to instantaneous noise, if the number of data points exceeding the judgment level is below a set value, they can be considered noise and excluded from the judgment.
Related Features
CF-0472 Shape Comparator Function (Optional)
In vibration and noise control for rotating machinery, it is crucial to measure and analyze at what rotational speed vibrations and noises become significant, and which components of the rotating machinery are causing them. The CF-4700A FFT comparator tracks fluctuations in rotational speed, extracts vibration and noise components caused by rotation, and can determine the quality of the equipment based on the level values or the patterns of change.
Related Features
CF-0472 Shape Comparator Function (Optional)
CF-0471 Tracking function (optional)
The variable component extraction function is a preprocessing function that extracts the "amount of variation" in the magnitude of a signal within a specific frequency band. It is effective in determining abnormal noises and vibrations caused by magnitude fluctuations, and can be used as preprocessing for pass/fail judgments regarding noises such as a "squeak" or rattle that occur when motor-driven equipment is in operation. In addition, the bandpass filter and envelope functions included in the variable component extraction function can be used for vibration monitoring of bearings, and vibrations can be made audible through the monitoring function (headphone output).
Related Features
CF-0473A Variable component extraction function (optional)
In production environments, unexpected momentary power outages or significant voltage drops can occur in the main line power supply. By installing this option, the device can secure sufficient power to shut down normally even if the main line power supply goes down, eliminating the need for a separate uninterruptible power supply. Furthermore, by pre-setting the startup conditions, there is no need to reconfigure the measurement conditions upon power restoration. This function also enables centralized power management via the main line power ON/OFF, eliminating the need to manually turn the device on and off.
Related Features
CF-0478A Power backup function (optional)
When opening and closing the door mirrors, if there are irregularities in the motor's rotation, a muffled noise with periodic fluctuations may occur. Therefore, the sound of the door mirrors opening and closing is measured using an MI-1235 1/2-inch measuring microphone + MI-3111 microphone preamplifier, and periodic fluctuations are extracted using the fluctuation component extraction function. The presence or absence of abnormal noise is then determined based on the amount of these fluctuations. By using the fluctuation component extraction function, it is sometimes possible to detect sounds that cannot be judged simply by the magnitude of the level.
Functions used
CF-0473A Variable component extraction function
Damage to a bearing causes abnormal vibrations. The signal from an acceleration sensor attached to the rolling bearing is input to the CF-4700A FFT comparator. The bandpass filter included in the optional fluctuation component extraction function filters the frequency band of vibrations caused by the damage, and the envelope function analyzes the fundamental frequency corresponding to the damaged area. The amplitude of that frequency is used to monitor the bearing condition and determine when maintenance is needed. In addition, the filter can be set by listening to the sound via the headphone output.
Functions used
CF-0473A Variable component extraction function
We perform quality control at the level of tracking analysis of the transmission's vibration signals. We receive rotational pulses from the rotation control controller of the transmission testing machine and perform tracking analysis. Vibrations are measured using the NP-3000 series preamplifier-integrated acceleration detector when the rotational speed is varied from idling to maximum output, and rotational tracking analysis is performed at the meshing order. An arbitrary judgment line is set on the analyzed tracking data to determine whether the transmission is OK/NG.
Functions used
CF-0471 Tracking function + CF-0472 Shape comparator function
The frequency spectrum of sound produced when metal parts (such as cast parts) are struck changes due to cracks and fractures. Therefore, metal parts are inspected by suspending them from a string to induce free vibration and measuring the sound radiated when struck. The sound produced when the part is vibrated with a hammer is collected using an LA-4440 integral-averaging precision sound level meter, and the AC output is input to a CF-4700A FFT comparator for frequency analysis. Based on the different spectral shapes of good and defective parts, the shape of the shape comparator is set to determine whether the part is OK or NG.
Functions used
CF-0472 Shape Comparator Function
Electronic components on the power supply board can emit sounds at power supply frequencies and high frequencies. Therefore, to avoid the influence of ambient noise, a simple anechoic chamber is used to measure abnormal sounds emitted from the power supply board. An MI-1235 1/2-inch measurement microphone and an MI-3111 microphone preamplifier are installed inside the anechoic chamber to capture the sound from the board, and the signal is input to a CF-4700A FFT comparator for frequency analysis. A judgment block is set with a shape that includes the frequencies where abnormalities occur, and OK/NG is determined by the area content of the spectrum.
Functions used
Block comparator function
Mechanical components, such as the harness devices built into the sliding door mechanisms of automobiles, can sometimes produce abnormal noises during operation. Therefore, we measure the noise generated when the harness is wound up by driving the motor of the harness device, which is set up in a simple soundproof box. We check the noise level using an LA-1410 integral average type general-purpose sound level meter inside the soundproof box, and input the AC output signal from the sound level meter into a CF-4700A FFT comparator for frequency analysis. A comparative judgment is then made based on the partial overall level in a specific frequency band.
Functions used
Block comparator function
When an imbalance occurs in the turbo fan, the signal from the vibration sensor increases. Therefore, we measure the vibration while the turbo fan is rotating. Using the signal from the NP-3000 series preamplifier-integrated acceleration detector, we determine the frequency band and judgment level to focus on using the CF-4700A FFT comparator, and set the judgment block. For the judgment method, we select peak max, and if the maximum value (maximum value) of the waveform exists within the set block area, it is judged as OK; otherwise, it is judged as NG.
Functions used
Block comparator function
| Digital I/O | Recommended connection circuit / specifications | |
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| DIGITAL INPUT Assign and use the following functions:
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Input type: Driven by contact or open collector (common isolation) Logic: Negative logic (Lo=1, Hi=0) |
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STATUS OUTPUT
This is a contact terminal that outputs [something]. |
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| Output type: Open collector (4 independent points, each signal isolated) Output voltage rating: 30 V Output current: Maximum 25 mA (sink) Collector saturation voltage: 1.0 V or less Logic: Negative logic (Lo=1, Hi=0) Compatible connector: FK-MC 0.5/8-ST-2.5 (Standard accessory from Phoenix Contact) |
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| COMP OUTPUT Select any 5 from the 20 judgment settings. This is the contact terminal that outputs the result. |
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| Output type: Open collector (5 points + common, all isolated) Output voltage rating: 30 V Output current: Maximum 25 mA (sink) Collector saturation voltage: 1.0 V or less Logic: Negative logic (Lo=1, Hi=0) Compatible connector: FK-MC 0.5/6-ST-2.5 (Standard accessory from Phoenix Contact) |
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| Power supply rating | DC 16V 3.3A |
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| AC adapter | Power rating: AC 100-240V 50/60Hz Power consumption: 65 VA or less / 150 VA or less (CF-0478A with power backup function: when charging battery) |
| Operating temperature range | 0 to 40°C (humidity 20 to 80% RH, non-condensing) |
| Storage temperature range | -10 to +50 °C (humidity 20 to 80 %RH, non-condensing) |
| Outline drawings | 220 (W) x 185 (H) x 220 (D) mm (excluding handle, stand, and protrusions)
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| Weight | Approximately 2.8 kg without options installed. Approximately 3.3 kg with optional equipment installed. (When equipped with CF-0473A variable component extraction function or CF-0478A power backup function, including battery pack) |
| Main unit cooling | Natural air cooling (fanless) |
| Applicable standards | CE marking |
| Vibration resistance | 9.8 m/s 2 (frequency 10 to 150 Hz, each direction of XYZ) |
| Shockproof | 400 m/s 2 (action time 11 ms) |
| Accessories | • AC adapter x 1 (PS-P20023, VM1391-VM1700 (2 m)) • Instruction manual x 1 • CD-ROM x 1 (Reference guide, utilities, DLLs for external controls, etc.) • SD card x 1 (512 MB, for updates only) • Terminal block connectors: 3 types x 1 each (FK-MC 0.5/10-ST-2.5, FK-MC 0.5/8-ST-2.5, FK-MC 0.5/6-ST-2.5) • Ferrite core x 1 (Seiwa Electric Co., Ltd.: E04SR301334) |
