How to accurately detect black incoming materials when there is only a 4mm gap at the bottom of the assembly line?
How to accurately detect black incoming materials when there is only a 4mm gap at the bottom of the assembly line?
A certain component assembly line, the customer needs to install sensors at the bottom of the line to detect whether there are workpieces passing above.In industrial automation production lines, the selection of sensors often determines the success or failure of the entire detection process. Especially when faced with the triple challenges of black workpieces, narrow installation spaces, and fixed mechanical structures, many engineers will encounter difficulties.
Today, we will take a real case to see how Akusense Sensing EFL-30NM ultra-thin photoelectric sensor cleverly solves problems.
Application scenario
This is an assembly line for a certain component, and the customer needs to install sensors at the bottom of the assembly line to detect whether there are workpieces passing above. The detection distance between the sensor and the workpiece is strictly limited to 11.3mm - this is determined by the existing mechanical structure, and the customer clearly stated, "The structure has been finalized and cannot be changed
At first, the customer attempted to use a regular mini red diffuse reflectance photoelectric sensor. However, a fatal issue was discovered during actual testing: the incoming workpieces were black. The black surface absorbs a large amount of light, causing the detection distance of ordinary red light sensors to sharply shrink from the nominal value, and the actual stable detection distance is only about 8mm.
This means that at an installation distance of 11.3mm, the sensor cannot reliably sense the "presence" of the workpiece, resulting in frequent missed detections and false alarms, greatly affecting the efficiency of the production line.
The working principle of a regular diffuse reflectance photoelectric sensor relies on emitting red light and receiving the light intensity reflected back by an object to determine its presence or absence. The darker the color of an object (especially black), the higher the light absorption rate and the lower the reflectivity. Therefore, if the intensity of the reflected light signal is insufficient, the sensor will "mistakenly believe" that there is no object, resulting in a significant attenuation of the detection distance.
Customers are unable to change the color of the workpiece (which is a property of the product itself), nor can they adjust the mechanical structure (which is a predetermined design), as if they have entered a dead end.
Solution - Ultra Thin Optoelectronic EFL
After on-site investigation and technical evaluation, we recommend Meiji Sensing EFL-30NM ultra-thin background suppression photoelectric sensor to the customer. Its appearance happened to hit all the pain points:
1. BGS background suppression technology - specializing in "black attenuation"
EFL-30NM has built-in BGS (Background Suppression) function, which does not rely on the strength of reflected light, but detects the landing position or energy distribution difference of reflected light through two internal receiving elements. When the distance of an object changes, the reflected light returns to the position of the receiver, and the sensor compares these signals to determine whether the object is within the set distance. Therefore, both black and white workpieces can be stably detected while effectively shielding against background interference.
2. 4mm ultra-thin size - a "pass" that does not change the mechanical structure
The thickness of EFL-30NM is only 4mm, and its external dimensions are only 20mm × 14mm × 4mm. Such a slim body allows it to easily fit into the customer's originally compact installation gap without any mechanical modifications to the bottom structure of the assembly line, perfectly meeting the customer's rigid requirement of "unchanged structure".
3. 30mm detection distance -11.3mm is more than enough
The standard detection distance of this sensor is 30mm, which is much larger than the customer's required installation spacing of 11.3mm. Not only is it fully covered, but there is also sufficient margin to ensure stable response even if there are slight fluctuations in the position of the workpiece.
4. Precise spot, high-speed response
At 30mm, the spot size of EFL-30NM is only 0.5mm × 0.5mm, which can achieve precise positioning; At the same time, the response time is ≤ 1ms, which can meet the rhythm of high-speed assembly lines and achieve "not missing one, not bad one".
Application Effect
After switching to EFL-30NM, the problem was easily solved:
At an installation distance of 11.3mm, the sensor's detection of black workpieces is stable and reliable, with no missed detections or misoperations; No need to modify any mechanical components, installation time is reduced to a few minutes; The production line has resumed efficient operation, and customers highly recognize the selection plan.
Summary of Technical Selection Experience:
Selection should be targeted: When facing color sensitive and distance limited working conditions, we should not only focus on ordinary diffuse reflectance sensors, but should give priority to products that are more compatible with principles such as background suppression (BGS) or laser displacement.
Size often determines feasibility: in a compact space, ultra-thin design is the "hard currency", and the EFL-30NM 4mm thickness becomes a key advantage.
Respecting the existing structure of customers: In industrial sites, making drastic structural changes often incurs high costs and takes a long time, but through clever sensor selection "subtraction", it is simpler and more efficient.
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Akusense Technology Co., Ltd.