　Aluminum foil is very thin aluminum, as defined by the International Standards Organization: the thickness ranges from 0.2mm to the extreme 0.006 mm. The manufacturing process of aluminum foil involves rolling from 2mm and 4mm plates. In this process, the aluminum blanks are cold rolled in sequence until the coil reaches the required thickness. Aluminum foil has good insulation properties against light, oxygen, taste, moisture, and bacteria. It is widely used in food and pharmaceutical packaging. In the twin mill process, two foils are separated simultaneously, allowing very thin foils (thickness ranging from 6 to 30µm) to be obtained.

　　Due to the micro-penetration of thin foil, production environment and other reasons, pinholes will inevitably be caused during the production process. The traditional approach is to arrange manual inspection of these pinholes during the rewinding process; however, due to human eye fatigue, limited human eye resolution, and high labor costs, 100% visual inspection of the foil cannot be performed. In order to detect these defects, many aluminum foil manufacturers use automatic detectors. As a professional aluminum foil inspection instrument, Thermo Fisher's MVI has an aluminum foil defect detection rate of 98% on the rewinding line.

【Detection Principle】

　　Based on the use of high-brightness LEDs and high-speed industrial cameras, the high-brightness LED beam is used as a light source. When a pinhole appears on the aluminum foil, the light beam penetrates the aluminum foil. The high-speed industrial camera serves as a light sensor and receives the light passing through the pinhole on the aluminum foil. . This very small light generates a signal telling the system that there is a hole, and based on the pinhole's size, shape, brightness and other information, it can calculate the pinhole's type, area and actual coordinate position.

　　Due to reasons such as detection accuracy and the size of the camera's photosensitive element, the detection range of industrial cameras is limited. For example, if the pinhole detection accuracy requirement is 0.1 mm, then the detection range of a 4K industrial camera does not cover more than 400 mm; when the width of the aluminum foil is greater than 400 mm, this means that multiple industrial cameras need to be used for detection. Generally, For adjacent industrial cameras, we will design a 15mm overlap area to ensure a 100% detection rate. The diagram below represents the arrangement of light sources and optical sensors as seen from the front, with overlap between each optical sensor. The number of cameras required is related to the width of the foil.

　　Advantages of using bright LED light sources: The beam is focused in one direction instead of in all directions. This avoids the impact of light reflection on the metal foil and ambient light on the product, greatly reducing the risk of false alarms.

【Technical Parameters】

Detection Object	Aluminum Foil, Copper Foil, Etc.
Typical Defects	Pinholes, Dents, Oil Spots, Stains, Scratches, Streaks, Bubbles, Inclusions, Etc.
Detection Speed	Max:500m/min
Detection Width	Adapt to any width (customized according to the production line)
Detection Accuracy	0.2mm~1mm(Depends on the number of cameras, production line width and vehicle speed)
Defect Identification	Automatic sound and light alarm, interception of current defect pictures and real-time X, Y coordinate defect distribution map display
History Record	Automatically record the picture, size, distribution location and other information of each roll of aluminum foil defects based on the batch number

【Defect Pictures】

【System Functions】

　　(1) Accurate defect map (X, Y coordinates) positioning display module;

　　(2) Automatic sound and light alarm, and display the current and previous 10 defect images;

　　(3) Real-time defect information display, recording the current defect type, area (diameter), horizontal and vertical position and other information;

　　(4) Basic product information module, which records product batch number, model, specification, shift number, operator and other information (the user can modify it according to the production situation);

　　(5) Real-time detection of meters and alarm information display;

　　(6) Automatic classification of defects based on characteristics such as defect area size, shape, grayscale difference;

　　(7) Automatic alarm for periodic and continuous defects;

　　(8) Automatically generate product defect records for each roll of products, and users can directly query according to the batch number;

　　(9) Automatically change rolls and automatically print a quality report of product information for each roll;

　　(10) Functions such as automatic statistics, saving, querying, calling and printing of detection history records;

　　(11) Long-term, large-capacity historical record storage;

　　(12) Automated linkage of production lines, remote technical services, etc.;

　　Note: The software functions can be customized and developed with special functions according to the different requirements of users.

【Field Application】