The effects of random noise shrinkage on rapid tooling accuracy

✍ Scribed by Paul Jacobs

• Book ID: 104314302
• Publisher: Elsevier Science
• Year: 2000
• Weight: 375 KB
• Volume: 21
• Category: Article
• ISSN: 0261-3069
• DOI: 10.1016/s0261-3069(99)00060-6

✦ Synopsis

This paper describes the effects of shrinkage variation on the accuracy of rapid tooling inserts. For processes involving a phase change, such as sand casting, investment casting, die casting, plastic injection molding, blow molding, and stereolithography, available data indicate that a component of 'random noise shrinkage' is superimposed on the mean process shrinkage. Analysis of data indicated that the standard deviation , of the random noise shrinkage, is directly proportional to the mean process s shrinkage, S. Assuming the noise is Gaussian, the maximum linear dimension, L satisfying a given tolerance, is shown to be max Ž . inversely proportional to S. A plot of L S is shown for various tolerance levels. A conclusion of this work is that tooling max concepts based on sintering metal powders must achieve S -0.1% to satisfy production tooling tolerances for dimensions up to 20 inches.