I have just upgraded my 3D printer.
The heated bed on my printer have been taking some time heating up. I've been guessing this is because the long and flat heating element looses a lot of heat downwards, with only a fraction of the heat going upwards towards the print zone. This is to be expected because the heating element is long, flat, and very thin. This means that the element has a huge surface area with very little mass.
This was the problem I wanted to solve. My thinking was to insulate the underside of the heating element. Most people know of the insulating properties of cork. It is very common to use circular cork mats to insulate heated pans from a kitchen bench. It's exactly the same thinking I brought to insulating the printer.
I bought cork mats from IKEA. These mats were meant to be kept under plates while eating to reduce mess. They are thinner than usual cork mats used for heat insulation, but they are thick enough for my purpose. The price for four of these are 29 NOK, I only needed one so I have a few for other projects. The description can be found here.
It was super simple to install. What I did was unscrew the print bed and then I used this to make a cut out of the cork mat. Then it was simply a matter of poking holes for the screws in the corners of the mat, and sandwiching everything back together.
I haven't analyzed the heat up difference with and without the insulation yet, but I will at a later time.
The heated bed does seem to heat up faster. I also imagine the printer uses less power during printing, because the heating element wont have to work as hard to maintain a stable temperature.
This is how the final product looks: