EXPERIMENTATION To analyze the effect the penetrating nozzle will have on the thermal properties of the hot end, Autodesk Fusion 360 was used to run an FEA analysis that simulated the lower half of the extruder during the heating process. The goal of this analysis is to replicate the heating that occurs when the extruder is moving back across the structure to the starting corner after laying down a pin layer. This analysis will allow us to see the maximum length the penetrating nozzle can be before significant cooling occurs in the nozzle. This will replicate the steady-state heating found during the printing process. The assembly of the E3D V6 All-Metal Hot End was fully modeled in 3D and meshed using Fusion 360's simulation software (Figure 6a). The mesh was generated using parabolic elements with a maximum aspect ratio of 10 and a minimum element size that is 20 % the average (Figure 6b). The heatsink and heatbreak (Figure 7a and b) was omitted from testing due to not affecting the nozzle's heating properties and so that the meshing done to it won't affect the meshing of more critical components (such as the nozzle and heatblock). The heatbreak and heatsink are designed to ensure that the filament doesn't heat up and melt outside of the melt zone of the nozzle and heatblock. Which, for this study is above the zone of interest and would only negatively impact the meshing size due to having to introduce larger elements that would skew the average size of elements. Material assignments are described in Table 2. Boundary conditions were also assigned to allow heat transmission from the heating element through to the filament by convection and radiation. Convection was set at the heatblock and nozzle at convection values of 10.00 W / (m2 / (m2 K), while an applied temperature was set at the thermocouple housing at 225°C (Figure 8)13,30 . This temperature was selected due to it being the printing temperature during the Z-pinning process. Radiation emissivity values were also applied for all materials involved in the study (Table 2). Accuracy of the model and simulations was experimentally verified by performing an analysis at 110°C while monitoring the temperature at the nozzle tip of a Prusa i3 MK3S+, which utilizes the same extruder modeled. To study what the effect of an extended nozzle would have on filament heating a FEA model was created based on the needle of McMaster-Carr's 22 Gauge reusable stainless steel dispensing needles31 . This was chosen due to its identical inner diameter compared to the stock nozzle exit. As well having a bass material of nickel-plated brass and www. sampe.org JULY AUGUST 2022 | cp Location Heaterblock (A) Material Aluminum Thermal Properties a = 2.36 x 10-5 cp Stock Nozzle (B) Brass K = 0.239 W / (mm °C) m / (m °C) = 897 J / (kg °C) a = 0.048 a = 2.05 x 10-5 cp Filament (C) PLA Plastic K = 1.3 x 10-4 a = 4.1 x 10-5 K = 0.115 W / (mm °C) m / (m °C) = 380 J / (kg °C) e = 0.03 W / (mm °C) m / (m °C) = 1800 J / (kg °C) a = 0.935 Figure 6. Model of meshed stock extruder with boundary conditions (A) and mesh settings (B). Figure 7. Full extruder assembly: heat sink (A), heatbreak (B), heaterblock (C), and nozzle (D). K) and 100.00 W Table 2. Material assignments for stock nozzle analysis (see Figure 8 for locations). SAMPE JOURNAL | 33http://www.sampe.org