ECTFE can be found in centrifuges, fluid processing components, and chemical storage tanks and ductwork. ECTFE’s exceptionally smooth surfaces and excellent fire resistance make it ideal for high purity applications in the pharmaceutical and semiconductor industries. ECTFE (Halar®) – With outstanding mechanical properties and dimensional stability, ECTFE has greater strength, abrasion resistance, stiffness, and creep resistance than softer fluoropolymers such as PTFE (Teflon®).Vespel® is commonly used in valve seats and sealing applications, high performance bearings and bushings, semiconductor and material handling machinery, and aerospace components. It has outstanding creep resistance and doesn’t lose its mechanical properties in extremely high temperatures (up to 500✯). Vespel® – Vespel® is a highly durable polyimide typically used in demanding applications that require excellent strength and impact resistance, low wear and/or low friction rates, and thermal resistance.Permanent deformation is known as creep rupture: the failure of a material due to continuous stress. It can occur as a result of long-term exposure to mechanical stress – including tensile, compressive, shear, or flexural loading – and is more severe in materials that are subjected to heat for long periods. What is Creep?Ĭreep is the tendency of a solid material to deform permanently under the influence of constant stress, even if the stress is below the yield strength of the material.
As experts in tight tolerances, Reading Plastic is well acquainted with creep-resistant plastics and can machine parts that will hold up under stress. Choose your infill to contribute to the strength, and use plenty of it, or design the part so that the infill is not intended to contribute to the strength.Applications that require tight tolerances and resistance to mechanical stress call for creep-resistant plastics that maintain their shape and integrity under load for long periods of time.
Be sure to print the parts so that the major stresses are along the strongest axes, typically X and Y, and not along the weaker Z asis. PET-G is a little better than PLA, but it softens at a lower temperature than ABS.Īs important as the material itself is the anisotrophy of the printer parts.
#Plastic creep calculation Pc#
I don't have experience with this.ĭepending on your printer, you can also consider using a higher temperature filament, such as ABS or PC (polycarbonate). This is claimed to allow the PLA to slowly recrystalize and become both stronger and usable at higher temperatures. There are PLA formulations which are annealed after printing. That temperature is hotter than your room, but a hot summer day in the sunshine could soften the part to the point of failure.įor anything load bearing, I would want a material with a higher plastic temperature. I have used this for force-fitting PLA parts by warming a pot of water and placing parts in it for a few moments. Raising the temperature of a normal PLA printed object to 160☏ (70☌) softens it to the point of nearly being limp. The problem with typical PLA may be the low temperature. It is also impossible to fully translate material specifications into component behavior without a really good model that includes the details of the infill, adhesion to peripheries, and all the microscopic detail of a real 3D-printed part. The problem is that creep involves both compression and tension, and the behavior may be different. The question is: under what conditions should you test them?
#Plastic creep calculation trial#
You need to print some trial brackets with materials of interest and measure them. Your question can not be answered theoretically - only empirically. I will of course add a safety factor and I could even fix the planks to the wall (in hidden places), but ideally the 3D printed material should have NO creep. Information: it's a living room shelf which will hold books and other stuff and is supposed to last a decade.
#Plastic creep calculation iso#
I found that the phenomenon is called "creep" and is related to ISO 899, but I couldn't find any data for the common filament plastics and I don't know the theory behind it, so I'm not sure whether it's unavoidable or it appears after a threshold stress is reached. Which material suffers the least from plasticity/non elastic deformation under stress?Īnswers with data for multiple materials are welcome. Still, this doesn't stop the author of the article from using PLA for a hanging shelf, which obviously is subjected to constant negative pressure. However, I read that PLA flows under constant stress/pressure. I would like to build a standing shelf where the supports which hold each successive plank are 3D printed (to obtain special shapes).