ASTM International

Standard Test Method for Measuring Shrinkage from Mold Dimensions of Molded Thermosetting Plastics
 N D6289

Annotation

This test method is intended to measure shrinkage from mold cavity to molded dimensions of thermosetting plastics when molded by compression, injection, or transfer under specified conditions.

This test method provides for the measurement of shrinkage of thermosetting plastics from their molds both initially (within 16 to 72 h of molding) and after aging (post–shrinkage at elevated temperatures).

This method will give comparable data based on standard specimens and can not predict absolute values in actual molded parts with varying flow paths, wall thicknesses, pressure gradiants and process conditions. Differences in mold shrinkage generally is observed between the specimen geometries described in this test method.

Knowledge of the initial shrinkage of plastics is important for the construction of molds and knowledge of post molding shrinkage is important for determining the suitability of the molding material for manufacturing thermosetting plastic components with accurate dimensions.

The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

NOTE 1—This test method and ISO 2577-1984 are equivalent when bars of 120 mm length, 15 mm width, and 10 mm thickness are used for compression molding; or flat, square plaques approximately 120 by 120 by 4 mm are used for injection molding.