This parameter also influences how prone a material will be to suffer from warping and cracking. The higher the Tg of a material, the higher the temperature that will have to be melted, and likewise, the greater the difference between the Tg temperature of a material, compared to the temperature of the environment and the bed, the greater the chances of suffering from warping and/or cracking.Īs an example, we can mention the two materials commonly used in 3D printing, the PLA that has an approximate Tg of 52☌ (125☏), and the ABS that has an approximate Tg of 98☌ (208☏).Īnd finally, Young’s modulus or longitudinal modulus of elasticity is a parameter that characterizes the elastic behavior of a material. But when the material solidifies and it is at a temperature lower than Tg, it is when thermal contractions begin to cause thermal stress. When the material is molten is not affected by thermal contraction. This value is known as glass transition temperature ( Tg). There is another value that tells us at what temperature a polymer decreases its density, hardness, stiffness and its percentage of elongation. In addition, with a closed 3D printer, the flow of air currents that can suddenly and drastically vary the temperature of the filament when leaving the nozzle, or the 3D printed model is prevented. Is important to have a closed 3D printer so the air temperature inside the 3D printer’s working area is kept as constant as possible and at higher than normal temperatures. We are talking about how big the temperature change will be in the filament when leaving the extruder and coming into contact with the air and the heatbed.Īll this translates into that the filaments that require higher temperatures to be melted will be more prone to warping and cracking, this due to the greater the temperature difference that will be between the three variables mentioned (the extruder temperature, the temperature of the environment and the temperature of the heated bed), therefore, the greater the dimensional changes that this material will undergo.ĭue to the aforementioned, when 3D printing with filaments that require high temperatures to melt (for example, PC), it is advisable to have a heated bed capable of reaching higher temperatures, and also a closed printer. It is extremely important to know this because it indicates that there is another variable that affects to a greater or lesser extent the possibility that our 3D print suffers from warping and/or cracking. The filaments that we commonly use in 3D printing (PLA, ABS, PETG, TPU, Nylon, ASA, PC) are made from materials that behave in the first way we mentioned (they expand by supplying heat and contract by exposing them to lower temperatures).Īs we already know, materials contract or expand depending on the temperature to which they are exposed, so the greater the temperature changes, the greater the dimensional changes. These materials are said to possess negative thermal expansion. The CLTE is the slope of the expansion curveįor general culture, we would like to mention that most materials tend to expand as we supply heat and otherwise contract, but there are materials that behave in reverse, that is, they contract as we supply heat and expand otherwise. NOTE: The CLTE values are expressed in 1×10 -5/☌ On the other hand, we have ABS with an CLTE of 11, which we know is quite prone to deformations and cracks. On the one hand, we have PLA with a linear coefficient of thermal expansion (CLTE) of 7.5, a material that does not suffer deformations or cracks. To give you an example that shows that this is true, we will use two materials that are widely used and known in the world of 3D printing.
It is important to know this because in this way we can conclude that a filament with a higher coefficient of thermal expansion will be more likely to suffer from warping and cracking than a filament with a lower coefficient of thermal expansion.
The coefficient of thermal expansion is the value that explains how pronounced this effect is in a certain material and is the quotient of the relative longitudinal or volumetric change between the temperature variation.
In materials science, there is a physical property that numerically represents how much a material contract or expand as a function of the temperature changes to which we expose said material, it is known as thermal expansion. In general, both drawbacks occur due to the same factors, what usually differentiates one from the other is that in the case of warping we will observe that the problem occurs with reference to the printing bed, and cracking will be observed between the layers of the 3D printed piece.
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