Runner sizing.(Optimized Runner Systems for Multicavity Injection Molds, part 1): An article from: Polymer Engineering and Science

This digital document is an article from Polymer Engineering and Science, published by Society of Plastics Engineers, Inc. on February 1, 1999. The length of the article is 5584 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

From the author: A strategy has been developed for optimizing the design of runners in injection molds with multiple identical cavities. This approach is based on mathematically rigorous derivations using the power-law viscosity model under conditions where the pressure drop in runners is not significantly influenced by temperature variation. The design rule to minimize runner volume for specified injection pressure and rate is simple: The diameter of any runner downstream from a junction is determined by dividing the diameter of the upstream runner by the cube root of the number of downstream branches at the junction. This rule has been extended to noncircular runners using the hydraulic radius approximation and the requirement of equal velocities in the circular and noncircular runners. Minimum volume cross-sectional shapes have been determined for U-shaped and trapezoidal shaped runners. For circular runners a method for estimating the pressure drop for nonisothermal flow quantifies the deviation from the pressure drop for isothermal flow at the melt temperature. As runner size decreases, the trend is for viscous heating to dominate over cooling and for the estimated nonisothermal pressure drop to be lower than the isothermal pressure drop.

Citation Details
Title: Runner sizing.(Optimized Runner Systems for Multicavity Injection Molds, part 1)
Author: Ching-Chih Lee
Publication:Polymer Engineering and Science (Refereed)
Date: February 1, 1999
Publisher: Society of Plastics Engineers, Inc.
Volume: 39 Issue: 2 Page: 375(1)

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