This page contains a Flash digital edition of a book.
Management of Permanent Molds


Thermal


Metalcasters have a suite of devices and resources available to achieve proper thermal management and control of permanent mold tooling. AFS INSTITUTE


A


casting cell in the permanent mold process cycles through five


process steps to make a part: mold preparation, metal pouring, solidifica- tion, mold opening and casting ejec- tion. Te majority of the cycle time is dedicated to solidification. Properly managing the solidification and tem- perature of the mold is required to achieve the quality and productivity goals of the casting cell. Casting geometry, material and


process determine solidification time. Molding with a metal die or tool, as in permanent mold, is a heat extraction process. Te mold’s job is to provide shape information and extract heat. The rate you can extract heat


drives the production rate. High speed sand molding releases heat quickly by producing new molds on a rapid basis. With metallic molds used in high pressure diecasting and permanent mold, a single mold must do all the heat extraction while peri- odically having hot metal poured or injected into it.


Several factors can affect solidi-


fication rate, such as mold materi- als, alloy type, and the geometry of the casting, but in this article, the focus will be on methods and prac- tices used to control the tempera- ture of the mold when those other


variables have already been set. Mold temperature can be managed


using thermal management tools such as inserts, water coolant and forced air


Two kinds of mold coatings are used on permanent molds: refractory and lubricating.


Bubblers provide targeted cooling in tight regions, such as deep metal cores.


February 2017 MODERN CASTING | 27


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60