Gate Size Calculator

Gate Width is calculated from an empirical relationship (Gate Width = square root of (Part Weight x 0.6 / Gate Thickness)), so heavier parts require proportionally more melt volume to flow through the gate in a reasonable time. Without widening the gate, the melt would have to travel through the same narrow opening at a much higher velocity, increasing shear heating and the risk of jetting or burn marks near the gate. Treat this output as a practical starting-point index rather than a precise physical derivation -- confirm gate width against your material supplier's or moldmaker's guidelines before cutting steel.

Gate Thickness is a percentage of Nominal Wall Thickness that scales with material viscosity -- 50% for easy-flow resins, 62.5% for medium-flow, and 75% for stiff-flow -- with a 90%-of-wall clamp as a safety net and a 0.3mm floor, neither of which is hit in normal use. Thicker-walled parts hold more heat and need a proportionally thicker gate to stay open long enough to pack the cavity properly before freezing off; thin-walled parts need a thinner gate to avoid an oversized, hard-to-trim vestige.

Estimated Fill Time increases with Flow Length -- the farther the melt has to travel from the gate to the last point of the cavity to fill, the longer it takes at a given flow rate and gate size. Very long flow paths (over roughly 300mm on this calculator) also push the Recommended Gate Type toward a Hot tip or Valve gate, since a simple edge gate may not deliver enough melt fast enough over that distance.

Material Viscosity is a three-way select (Easy flow like PE/PP/PS, Medium flow like ABS/SAN, or Stiff flow like PC/POM/PA) because flow behavior is a category property of the resin, not a continuous number. Stiffer-flowing materials need a thicker gate and take longer to fill for the same part geometry, which is why this input feeds directly into both the Gate Thickness and Estimated Fill Time calculations.