Queendom Tools

Polymer Cooling Time Estimator

Introduction

For process engineers sizing a cycle before they tie up a press — a thicker wall or a colder mold changes cooling time by the 1D conduction relation `t = (h²/(π²·α))·ln((4/π)·(Tm − Tc)/(Te − Tc))`, and this estimator gives that number in seconds from five inputs. This tool helps you quickly estimate the cooling time for a molded polymer wall, considering its thickness, thermal diffusivity, and relevant temperatures. Understanding these factors is crucial for optimizing cycle times and ensuring product quality in injection molding processes. The formula used here is `t = (h^2 / (pi^2 * alpha)) * ln((4/pi) * (Tm - Tc)/(Te - Tc)) for 1D heat conduction`.

How to Use This Tool

  1. Enter wall thickness h in mm — the thickest nominal wall of the part, since h is squared in the formula.
  2. Enter thermal diffusivity α in mm²/s for the resin, taken from its material datasheet.
  3. Enter melt temperature Tm and mold temperature Tc in °C for the run you are planning.
  4. Enter eject temperature Te in °C — it must be below Tm, or the estimator reports an invalid input.
  5. Read the cooling time in seconds (minutes shown beneath) and the formula with your values substituted.

FAQ

Q: What formula does this polymer cooling time estimator use?

A: The 1D heat conduction solution t = (h^2 / (pi^2 * alpha)) * ln((4/pi) * (Tm - Tc)/(Te - Tc)), with h in mm, α in mm²/s and all three temperatures in °C, giving t in seconds.

Q: What units does the estimator expect?

A: Wall thickness in mm, thermal diffusivity in mm²/s, melt, mold and eject temperatures in °C; the result is in seconds, and α must be in mm²/s for the seconds to come out right.

Q: Why does doubling the wall thickness quadruple the cooling time?

A: Because h appears only in the h²/(π²·α) term — halving or doubling h scales the result by four, while the logarithmic temperature term is untouched.

Q: What happens if my eject temperature is above the melt temperature?

A: The estimator treats it as invalid and shows an error instead of a time, because the formula requires Te below Tm.