The following plot shows the pvT diagram of PA 66. Assume the melt is injected at...

 

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The following plot shows the pvT diagram of PA 66. Assume the melt is injected at 275 °C to a maximum pack/hold pressure of 800 bars. The 800-bar pack/hold pressure is maintained until the gate freezes off, at which point the part is at an average temperature of 175 °C. Then, the pressure drops to 1 bar as the part cools inside the cavity until the part is ejected from the mold and cooled to 25 °C. (a) Trace the process cycle on the plot below and estimate the final part thickness if the mold thickness is 3 mm. Assume all the shrinkage leads to part thickness reduction due to mold constraints. (b) What would be the final part thickness if the part is allowed to shrink in all directions? Specific volume, V (cm³/g) 1.05 1.00 0.95 0.90 0.85 0 PA 66 100 200 Temperature, T (°C) Pressure, P (bar) 1 200 400 800 1200 1600 300 The following plot shows the pvT diagram of PA 66. Assume the melt is injected at 275 °C to a maximum pack/hold pressure of 800 bars. The 800-bar pack/hold pressure is maintained until the gate freezes off, at which point the part is at an average temperature of 175 °C. Then, the pressure drops to 1 bar as the part cools inside the cavity until the part is ejected from the mold and cooled to 25 °C. (a) Trace the process cycle on the plot below and estimate the final part thickness if the mold thickness is 3 mm. Assume all the shrinkage leads to part thickness reduction due to mold constraints. (b) What would be the final part thickness if the part is allowed to shrink in all directions? Specific volume, V (cm³/g) 1.05 1.00 0.95 0.90 0.85 0 PA 66 100 200 Temperature, T (°C) Pressure, P (bar) 1 200 400 800 1200 1600 300

Answer rating: 100% (QA)

Solutions Step 1 a To trace the process cycle on the plot we start at point A which is the initial s... View the full answer