Heated bed - Does it have to be ON throughout the printing session?

A very Happy New Year to all forum users and moderators!

After a (very) long pause to my printing sessions, I came back to print a tunnel portal for my train model layout.
As I watched my design come to life, the question just hit me:
Do we need to keep the heated bed ON throughout the print?
I mean, the heated bed has a very specific purpose: to keep the first layer(s) of the filament in such a state that they stick well to the build plate so that as printing progresses, everything stays in place and you get a solid object in the end.
However, as the print head moves a way from the first layers, do we still need to keep the heating on? Will the part(s) run the risk of getting detached from the printing surface?
If this is not the case, it would be interesting to add a few lines of G-code to gradually reduce the temperature of the heating bed to a full shutdown thus preserving electronics and saving a few watts during printing...

I would be more than grateful if anyone of the experts out there could answer this (possibly silly) question....

Many thanks in advance,

Nikolas

P.S. I am using a Wanhao di3 v.2 with no mods and am printing mostly in PLA

If you don't mind the first layer disengaging from the bed after it cools, it's okay to turn the heated bed off. Unfortunately, if the first layer disengages, the rest of the model will follow.

When printing on a heated bed, the first step to getting the model free is to let the bed cool. If it cools during the print, you'll have a mess on all the layers after the model starts to slip and slide. Jams and broken parts could also result, depending on the severity of the mess created. The latter is unlikely but not impossible. Another possibility, much more likely is that the extruder nozzle will accumulate a huge blob of filament that is very difficult to remove and CAN result in broken parts.

Thank you very much for the explanation.
Trust me, I would never like to have a part moving while it is printed!
My (foolish-looking) suggestion was triggered from the fact that I always struggle to remove the prints from the bedplate after completion, even well after the bedplate has cooled down to room temperature, so I just imagined that it would make no difference if we turn it off sooner...
FYI, I'm only using the standard issue sticker that came with my printer with no other additions whatsoever...

Kind Regards,

Nikolas

If you are having trouble removing the prints after cooling, then there is a much stronger chance your suggestion would work. With glass beds, once the print has cooled, with no other adhesive involved, the part is a simple lift removal. Some users/printers have no heated bed and use blue painters tape or spray on adhesive on a cold surface.

I should have considered to ask if you were using adhesive. You may get away with a cooled bed after all.

get a sheet of pei.
prints stik when hot and not when cold. Sounds like magic - but really works :-)

What happend when you turn the bed off is that the plastic shrinks - just a tiny bit with pla and a lot with abs - but that shrinkage is often sufficient to dislodge the part.

It seems that Nikolas wants to stop the heat before the print is done. Using PEI, which I agree, is a great coating, would most certainly release the build prematurely.

For the rather minimal cost savings of turning off the heat, it simply does not seem worth the risk of losing a print that releases and shifts on you.

At best, you might be able to gradually reduce the heat when its near 80% complete and rely on the residual heat of the build plate to hold the part down, but then the electricity savings would be even far less with still the risk of a print releasing.

just keep it on :-)