Recently moved to a gym that uses padlocks for locking your stuff, they sell them too for an inflated price of 3.5$, jokingly I tried my key on a friend’s lock, and one more random one, of course it didn’t work and it made me curious.
My question is how do factories make all keys/locks different even at these cheap mass produced kinds that are probably sold for 0.5-2$, how is it worth for a factory to “use different patterns” at that price, or how do they do it?
In: Engineering
You are getting told that there aren’t a lot of different permutations for each lock model produced, but there still are maybe 100-200 per model. I think you’re still asking about the manufacturing process though, which I don’t think anyone has answered.
I don’t have direct insight into this, and I’m sure each manufacturer does it differently anyways. But this type of system can be automated. Lock manufacturers don’t have a separate mold for each key. They can either buy key blanks from another company, or make their own. Then they mill down those blanks themselves (or even have that process done by someone else).
Say they have 200 combinations and they want to make a manufacturing run of 10,000 locks. (Made up numbers.) Thats a run of 50 keys per combination. They set up the machine for combination number 001, run it through 50 times, and put all those keys into bin number 001, to get bundled with locks in lock bin number 001. Then they change the milling instructions slightly and move on to bin number 002.
This process can be automated. The instructions for the machine to mill position X on the key down to setting number 1 are trivially different than milling position X down to setting number 2. For example, you could tell the milling machine to increase the value for position A by 1 every 50 keys, position B by 1 every 150 keys, position C every 450, and so on. If you had 5 positions with 3 values each, and 50 keys per combination, this would lead to 50 x 3^5 = 12150 keys you could make. You would probably skip every combination that results in the key looking like a straight line though, because your customers wouldn’t trust that key.
Again I don’t have direct insight into this process, and every company would do it differently depending on their manufacturing processes and capabilities. But unless the runs are really big, they probably aren’t stamping them — like you said, it wouldn’t be worth it to set up that many patterns. But a milling machine in a tool and die shop can whip through thousands of pieces pretty quick (way quicker than a regular key making machine can), so they don’t need to have separate patterns.
Back before you could computerize the milling machines, the ones used in key manufacturing were probably a little more specialized, and someone may have manually increased the milling value after every 50 keys or whatever. Maybe just a series of knobs on the machine and a counter that would tell you how many have went through. But again, I don’t have first hand experience — I’ve just seen a few tool and die shops running, and I’m going based on that very loose knowledge to extrapolate into key making. There’s probably some video somewhere on YouTube that shows how one of those companies makes their keys. Keys are typically brass, so milling them isn’t as hard on your machines as something like stainless steel.
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