Many basic printers do not come with a heated build plate, but it is necessary to have one if you would like to print in materials with high mechanical properties.
Glass Transition Temperature
The glass transition temperature (Tg) is the temperature region where the polymer transitions from a hard, glass material to a soft, rubbery material. Prints will often deform around this temperature, but it is needed for the bed to heat to just around a materials glass transition temperature in order to have good bed adhesion. You can get away with printing PLA on a non-heated bed, but any material with a high Tg will require a heated bed.
Thermoplastics are very sensitive to temperature fluctuations, specifically when they are being rapidly extruded at temperatures well above their glass transition temperature. When there is a significant diference in temperature on one side of the HBP compared to the other, we call that a temperature gradient.
These temperature gradients and environmental fluctuations are the leading factors that lead to part failures due to warping. Temperature gradients above the HBP can also lead to an effect known as “delamination”, where the print remains adhered to the bed, but individual layers above the HBP surface begin to weaken and separate from each other. So if you want to have strong parts that print reliably, a good starting point would be to ensure your HBP is as uniform and gradient-free as possible.
Since we have been researching the effects of HBP thermal gradients for quite some time, we decided earlier this year to take a shot at fixing the issue. We incorporated a very special bed stack into our beta 3DGenie (3DG) automated FDM printer with the aim to eliminate significant gradients at the print suface (pictured to the right)