On the glass plate, measure a metal "sesame seed"
On the glass plate, measure a metal "sesame seed"
When serving equipment integrators in the precision manufacturing industry, we frequently hear similar demands: can we detect metal particles on glass plates? The particles are very small, smaller than sesame seeds; the internal space of the equipment is very crowded, and the sensor is very small; mobile phone lens assembly, semiconductor packaging, medical equipment, lithium battery equipment ...... In these industries, similar scenes are increasing.
In the last year or two, Xiaoming frequently heard similar needs when serving equipment integrators in the precision manufacturing industry:
Can you detect metal particles on the glass plate?
The particles are very small, smaller than sesame seeds.
The internal space of the equipment is very crowded, and the sensor should be very small.
At first, we thought this was just a special requirement of individual customers. Later, we found that mobile phone lens assembly, semiconductor packaging, medical equipment, lithium battery equipment... In these industries, there are more and more similar scenes.
A precision equipment manufacturer came to us this year.
Their equipment needs to complete a self-test before leaving the factory: the presence of metal particles on the glass plate.
Analysis of Difficulties
The particle diameter is less than 0.5mm, smaller than sesame, almost invisible to the naked eye.
The glass plate is transparent, the sensor beam hits it, and the reflected signal is extremely weak.
Behind the glass panels is a complex set of mechanical structures with a cluttered background.
What is more troublesome is that the installation position of the sensor inside the device is only the thickness of the finger.
The customer said that they have tried several photoelectric sensors:
Ordinary diffuse reflection type: the light spot is too large, small particles are not covered at all, and often missed detection.
The opposite type: the installation space is not enough, the two sides are not right.
Background suppression type: For the combination of small transparent glass particles, the signal fluctuates greatly and false alarms are frequent.
Selection Recommendations
After receiving the demand, we did not directly recommend a certain product, but did one thing first: to reproduce the customer's on-site conditions.
We built a simulation platform in the lab:
Transparent glass plate customer sent over metal particles.
Then test several possible applicable sensors one by one.
The test found that there are two core difficulties:
Insufficient signal contrast: the glass reflection is weak, the difference between the particle reflection signal and the background is too small, and the sensor is difficult to judge stably.
Contradiction between spot size and installation distance: installation distance must be ≥ 80mm (limited by equipment structure), but at this distance, most sensor spots on the market have diverged to about 5mm and cannot be focused on 0.5mm particles.
Finally let us decide to chooseAkusense This mini photoelectric sensor: PDL-C series
Why does it work?
Don't blow the parameters, just say the difference we actually saw in the test:
First, the light spot is really small.
Laser light source, at a distance of 100mm, the measured spot diameter is about 2mm.
This means that the energy is highly concentrated, hitting the 0.5mm metal particles, and the reflected signal intensity is much higher than the glass background.
Small goals can finally be seen.
Second, the size is small.
The Mini size of the PDL-C is shorter than a finger.
The inside of the customer's device was very crowded, but the sensor found its place with little effort.
There is no need to change the structure and reopen the mold.
Third, the metal and glass background has been optimized.
Its light source has been adjusted to capture the diffuse reflection of the metal surface is more sensitive; at the same time, the receiving circuit has a better ability to suppress the stray light of the glass light transmission and irregular background.
Application effect
The sensor was mounted vertically about 80mm above the glass plate, and the light beam was directed perpendicularly to the surface of the glass plate.
With the sensitivity fine adjustment knob, the threshold is set above the reference reflection when there are no particles, ensuring that the ON signal is output only when metal particles appear in the spot area.
Key parameter information
If you also face similar detection problems, welcome to communicate with us! We will provide you with solutions to help your production line achieve intelligent upgrades!
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Akusense Technology Co., Ltd.