Most washing machines have a timer that prevents you from opening the hatch just after the washing cycle ends. Instad you must wait for the timer to go off, usually a minute or two, before you can open the hatch.
Why? Would letting the user open the hatch immediately after washing ends pose any safety or other issues?
Well, imagine someone opening the door if the water hasn’t fully drained out and the ensuing mess. If you’re wondering if someone is stupid enough to do that, then the answer is unequivocally yes. There is a reason the door locks for that amount of time - so somebody doesn’t brain fart, open the door, and flood the laundry room.
So why not make the washing cycle end when the water has fully drained? I get the impression the timer starts after the drain.
Maybe that’s your machine being oddly programmed. Every machine I’ve seen unlocks right after it finishes it’s cycle. It can also be stopped and unlocked anywhere halfway, but it takes some time to drain the water (usually a few seconds, not a full minute like you mentioned originally).
It’s not a component aware system. The last phase is generally the spin cycle. The controller knows to trigger the spin cycle, it knows to stop the spin cycle after a period of time. What it doesn’t know is whether those things actually happened. Particularly, it doesn’t know that the drum has actually stopped spinning. So, it just wait a predetermined amount of time before unlocking the door.
In the case of my own device the door actuator uses a wax motor. Put simply, current is changed to heat which melts the wax, pushing a pin the locks the door. To open the door, current is removed, the wax cools, hardens and shrinks and the pin slides back. Now the door can open. So, even if I remove power during a cycle the door will eventually unlock as the wax cools.
Many machines use a bimetal to lock the door, a stupidly simple design. Metal heats up, bends and triggers the lock. It takes a while to cool down which is why it’ll take a while to unlock even if you unplug the machine.
In case you’d like to see bigclive explain it in detail: https://www.youtube.com/watch?v=PIm7q_U3UEM
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My bet would be it’s waiting for temperature to drop.
Edit for the downvoting folk: Some of the profiles of my washing machine have temperatures of up to 90°C
It checks if the water is really truly out so opening the hatch is safe (as in no water coming out causing water damage). And for that it waits a time so the water has time to gather in the bottom.
But why not just beep after that? What’s the point of beeping before the door is unlocked?
Mine beeps when the door unlocks, but I’ve seen many that beep before the final check. Either to satisfy some “1 hour wash cycle” target or perhaps they expect people to walk to the machine when it beeps and the check isn’t that long so it’s probably going to be unlocked when you get there?
