Tuesday 12 December 2023

PA6.6 vs. PARA - Reducing the Wall Thickness of Injection Moulded Parts (Geometry Optimization Example)

Hello and welcome to this blog post. Today we discuss the wall thickness optimization of an injection moulded part which is exposed to deflection load and is made out of Polyamide 6.6 with 50 wt% glass fiber reinforcement. We will replace the PA 6.6. with a glass fiber reinforced PolyArylAmide (PARA; MXD6) and check how much we can reduce the wall thickness. Learn about the difference between aliphatic Polyamides and PARA here and the ABC's of PARA you can find here

Background of geometry optimization: wall thickness reduction

Basis of our calculation is the deflection (Y) equation of a beam with a uniform distributed load F where both ends of the beam are fixed (Figure 1). The current part made out of PA 6.6-GF 50wt% has a thickness of 3mm and the material has a Young’s modulus of 12.5 GPa (conditioned; Ultramid(R) A3WG10). The selected PARA has a Young’s modulus of 20 GPa (conditioned; Ixef 1022). Inserting the Young’s modulus of PA 6.6. and PARA, results that by using PARA the part stiffness will be 1.6 times higher compared to PA 6.6. 

Figure 1: calculation path for part geometry optimization with PARA-GF 50wt%.

Next we want to know how thin we can make the part by using a high modulus material such as PARA with 50 wt% glass fiber reinforcement and keeping the stiffness level. In order to calculate the wall thickness reduction, we need to rearrange the equation for the moment of inertia of a rectangular shape. By inserting 3 mm as current wall thickness, we will get 2.4 mm wall thickness when using PARA. This is a 20% reduction in wall thickness and will lead to less overall material consumption and reduced cooling time (more output). 


Geometry optimization with high performance polymers allows one to have a stiffer part, a part with reduced wall thickness, and by adding ribs, it is possible to have a stiffer part with reduced wall thickness. 

Thanks and #findoutaboutplastics


Herwig Juster

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[1] https://www.findoutaboutplastics.com/2020/07/metal-replacement-with-high-performance.html

[2] https://www.albis.com/de/products/download/doc/de/SI/basf/UltramidA3WG10.pdf

[3] https://www.matweb.com/search/datasheettext.aspx?matguid=c718c0314b2b49b78f27aaa4190a53d4

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