Micro-Leakage Helium Detector for EOE
eoe helium testing bench
helium Detecting Bench
Easy-open end helium testing
Micro-Leakage Helium Detector
Micro-Leakage Helium Detector for EOE
Leakage-free is a most basic and important requirement of EOE quality. Even small leakage may lead to great scrapping at user ends, generating costly compensation. Therefore, it is an important quality issue for almost all EOE manufacturers to reduce leakage during EOE production and avoid or stop such products from flowing to user ends.
However, during the forming of EOE, various procedures may result in leakage. For example, basic shell thimbles may be ripped during the forming process, score leak in the process, crackles appear at rivet tops and bends, rupture of rivet roots due to burr of pull ring holes and leakage points formed by the impress of aluminum scraps on rivet surface, etc. Modern production lines of EOE are mostly of multi channels and high speed and it is nearly impossible to eliminating the production of easy-open with leak. Therefore, besides controlling various parameters during production, it is almost the final method to carry out sampling detections of product leakage to avoid and prevent products with leakage from flowing to user ends.
It is necessary to choose appropriate detecting methods and means according to the leakage situation of easy-open lids. For example:
1. Ripping of thimbles of base covers As the cracks are big and can be found with naked eyes, air-pressure or hydraulic-pressure detections can be adopted, which is fast, reliable and economic. Such defects can be found easily at customers during filling without large-area spreading of defect products.
2. Crackles at rivet and tangents Usually cracks are tiny. The omission factor is high while air-pressure or hydraulic-pressure detections are applied, even tiny leakage cannot be detected. Crack detection at these areas requires very precise detecting means.
Among manufacturers of easy-open lids, leakage at rivets/tangents occurs most often. Such leakage has such features. 1. It can hardly be found from the online appearance detection; 2. The leakage is small; 3. When leakage is found at user ends, often beverage or food has been filled and stored for a period and even has sent to terminal markets. Therefore, the spreading area of defect products is very large and the control of the situation is very difficult and costly. It is the most important thing for easy-open EOE manufacturers to control product quality by preventing products with rivet/tangent leakage from flowing to user ends.
So far, there have been two successful detecting means for the leakage at rivets/tangents, which are fluorescence detection and helium gas detection. A detailed comparison between these two detection methods is given as below.
Fluorescence detection: Smear fluorescer on a detected position of EOE (usually on the rivet and neighboring area) to stay for 20~30 minutes. Use an ultraviolet lamp to irradiate the back of the detected position. If leakage exists on the back, the fluorescer will penetrate the leakage point to gives out brilliant yellow-green fluorescence under the irradiation of the ultraviolet lamp to identify the leak.
Helium gas detection: Put the detected EOE on a testing bench and separate the external environment and the detected area inside the equipment using very high vacuum. Discharge helium gas in the external environment, meanwhile exert high-pressure electrode in the detected area inside the equipment. In case leakage appears at any position of the lid, helium molecules in the external environment will enter the detected area inside the equipment through the leakage point, be ionized into helium ions and enter helium ion inspection room through a specific magnetic deflection field. The existence and quantity of helium ions will be detected and alarms will be given to indicate the leakage existence and its severity.
2. Detection Precision
Fluorescence detection: As enough penetrating time (20~30 minutes) is given, fluorescer usually penetrates at even tiny leakage point, indicating the leakage situation of the lid. It has high precision and reliability.
Helium gas detection: In normal temperatures and pressures, helium is in gaseous state and the helium molecules have nearly the smallest structure. It can be said that helium molecules can penetrate any macroscopically solid matter with structural gaps. Therefore, the helium gas detection has very high precision. In real equipment, the detection precision has reached 10＾(-7) milliliter/second, that is 3.15 millimeter/year. This precision has far exceeded the real requirement of the industry of easy-open lids. The helium gas detection has the highest detection precision so far.
3. Detection Speed (Feedback Speed of Detection Results)
Fluorescence detection: In consideration of the required time of fluorescer penetration, manual fluorescer smearing on every EOE and irradiating it with an ultraviolet lamp will be time-consuming. In usual, one surveyor needs about 3~4 hours to detect 1,000 easy-open lids.
Helium gas detection: It enables multiple batches detection and time required for every batch detection is very short. In usual, one surveyor needs about 0.4 hour (about 20~30 minutes to detect 1,000 easy-open lids).