There are many types of materials that can be used for 3D printing. For the fused filament fabrication (FFF) 3D printers, plastic is the main printing material.
Plastics are polymeric materials that come in many different formulations. Some of the most popular plastic filaments you can buy are:
Filaments are typically in 1.75mm nominal diameter and in a kg or less rolls. They are available in various colours. Some of the filaments may also contain fillers to enhance properties such as their stiffness, strength, appearance etc.
PLA material is a low cost and easy to print with material especially for enthusiasts that use open printer designs and basic desktop printing technology.
PLA has a high stiffness, for example compared with ABS. It has also low warping that makes it straightforward to print with.
PLA also produces less odours than ABS. It is derived from plants meaning it is biodegradable.
A heat bed certainly helps adhesion of the first layer and reduces the warping and lifting of the edges of a print.
Materials with a higher melting point such as ABS and materials with fillers will definitely need a heat bed that can achieve uniformly high temperature on the printing surface.
Most failed prints are due to adhesion problems and due to surfaces that are not uniformly heated which can be the case with basic low power heat bed designs.
Using either glass or aluminium print surface provides different textures to the print.
Typically a glass surface gives a gloss finish whereas the aluminium surface gives a matte finish to the printed object on the side facing the heat bed. This will depend on the surface roughness and texture of the printing surface.
3D printing enthusiasts may also find that it is difficult to separate the print from the surface. In many cases leaving the print to cool down is enough to let them separate without even touching the object!
So what happens during cooling period? The fused filament and glass are at the same temperature during printing process. But when the printing completes, both the print and the print surface begin to cool down. Each of them have a different thermal expansion characteristic. This means that cooling process effect causes differential shrinking of each surface. As a result a shearing force occurs between the print surface and the print. This helps to separate the surfaces.
If you are in a hurry to print your next object, it is a good idea to use another spare printing surface on your heat bed.