How to set the upper and lower limits of the online dynamic checkweigher?1
The dynamic weighing characteristics of the checkweigher conform to the normal distribution curve. The same product will have different values u200bu200bwhen measured multiple times. These values u200bu200bwill be distributed in the interval of the normal distribution curve. The user requires a smaller range of upper and lower limits for rejection, that is to say, the upper and lower limits of rejection requested by customers cannot be used as the upper and lower limits for checkweigher rejection. If this is done, many unqualified products will enter the qualified range. Specific settings The test data can be obtained through the blind zone test and then set. 1. The usual setting method is to add or subtract 3 times the standard deviation from the nominal weight range of the product as the upper and lower limit values. This setting method has an inaccuracy rate of 0.3%. A nonconforming product range of 6 times the standard deviation will also be included. This setting can allow most of the qualified products to pass, ensuring the continuity of production, but there may be unqualified products entering the qualified range (depending on the position of the critical point of unqualified products). 2. If 100% of qualified products are not rejected, then the standard deviation of 3 times needs to be enlarged to 4-6 times of standard deviation. Although this setting meets the requirement of 100% of qualified products not rejected, there will be more unqualified products. The product enters the qualified range. 3. To meet 100% rejection of unqualified products to meet this requirement, you have to use the heaviest product in the ultra-light unqualified products plus 4-6 times the standard deviation as the lower limit of qualified products, and use the overweight unqualified product The product with the lightest product minus 4-6 times the standard deviation is used as the upper limit of the qualified product. If the user's product distribution range is relatively concentrated near the average range, fewer qualified products will be mistakenly rejected, and it can be guaranteed that 100% of the products in the unqualified range will be rejected. 4. Ideal condition The picture below is the interval setting condition under ideal condition, which is related to the uniformity of the user's product and the application of rejecting unqualified products required by the customer. In this state, 100% of unqualified products can be rejected, and 100% of qualified products can be passed. In summary, the upper and lower limit settings of the checkweigher need to be determined according to the specific requirements of the customer and the accuracy of the checkweigher machine. Zhongshan Kenwei is a professional checkweigher manufacturer with many years of experience in weighing instrument manufacturing. The products are sold at home and abroad. We tailor-made online checkweigher solutions for your production line. You are welcome to contact us at any time for more details!
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