How padlocks are made
The classic padlock body is a stack of punched steel plates riveted together like a deck of cards.
- stations
- 7
- things upstream
- 76
- raw sources
- 25
- steps from the ground
- 11
The short version
A laminated padlock body is built from sheets of steel punched into plates, stacked and riveted so that a hollow in the middle holds the lock mechanism. The riveted body is electroplated against rust. The shackle is a hardened steel bar bent into a U, and a brass cylinder with pins and springs goes in last.
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Punch the plates
A press cuts plates from steel sheet, each with a hole in the middle. When the plates are stacked, the holes line up to make the cavity for the lock.
Goes in -
Stack and rivet
Workers collect the plates in order and rivet them together. Those rivets must clamp hard without squeezing the bores out of shape.
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Electroplate the body
The whole riveted casing goes into a plating bath, which puts on a metal skin against rust. Plating the casing as one piece saves doing every plate singly.
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Bend and harden the shackle
Steel rod is bent into a U and heat-treated until it is hard enough to resist bolt cutters and saws.
Goes in -
Make the lock cylinder
Brass bar is machined into a cylinder with holes for pins and springs, and the keyway is cut.
Goes in -
Fit the mechanism
Pins and springs are loaded into the cylinder, which is slid into the cavity, and the shackle is latched into place.
Goes in -
Cycle the key
The key is turned to check that the lock engages and releases.
Worth repeating
- Padlocks have been used in China since the late Eastern Han dynasty, 25 to 220 AD.
- A padlock with spring tines, dated to 850 AD, was found at the Jorvik Viking settlement in York, England.
- Harry Soref started Master Lock in the early 1920s with the first laminated padlock.
Back to the ground
Follow every input upstream and padlock starts as these 25 raw sources.
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Sources
Cite this page: "How padlocks are made." Assembly Line, 2026-11-03. https://assemblyline.org/make/padlock