What is the mutual opening rate of keys?
During the production of anti-theft door locks, based on the processing accuracy and the number of beads, the manufacturer knows the maximum combination quantity in advance. According to this arrangement, the combination is continuously produced in cycles, and there is a mutual opening rate. Mutual opening rate refers to the proportion of a certain number of locks in the same batch that are mutually opened within a specified time (the percentage of the quotient of the number of times they are opened and the total number of attempts).
The fewer locks a key opens, the stronger the safety and reliability of the lock. The powerful and well-known lock brands is strong, with a mutual opening rate of only tens of thousands of times, while some informal and powerless manufacturers may have a mutual opening rate of tens of times, which means that these manufacturers may only have dozens of sets of molds for producing locks.
At present, China divides the anti-theft door lock cylinder into three levels: A level, B level, and super B level. According to the corresponding national standards, the mutual opening rate of Class A locks should be ≤ 0.03%, meaning that three out of ten thousand locks are the same; the mutual opening rate of B-level lock is ≤ 0.01%; The mutual opening rate of super B-level locks is lower, about ≤ 0.0004%, which means that 4 out of 1 million locks are the same.
The principle is actually very simple. The lock in the above picture has five pairs of marbles (namely five upper and five lower marbles), which can slide up and down in the corresponding marble holes. When the correct key is inserted, the five upper marbles return from the lock cylinder to the lock body, exactly flush with the contact surface between the lock cylinder and the lock body. At this point, the key drives the lock cylinder to rotate and unlock. If the keys do not match, the marbles will get stuck at the joint between the two, and the key will naturally not open.
The number of teeth in the corresponding key of the same set of locks is determined by two factors, one is the number of marble holes, and the other is the number of marble levels. As mentioned above, the number of marble holes refers to the number of marble lengths (the sum of the lengths of the upper and lower marbles is determined), and their lengths are not arbitrary, but have a certain level difference. So it's easy to calculate the number of different teeth on the key.
For example, when the number of pinhole is 4 and the number of marble hole stages is 5, there are 5 ^ 4=625 types of teeth; when the number of marble holes is 6 and the number of bullet stages is 5, there are 5 ^ 6=15625 types of teeth (in actual production, the number of teeth is smaller than the theoretical value because some special teeth need to be removed).
*Originally from Intelligent Door Lock Research Pro, if involved in copyright issues, please contact us for prompt deletion.