1.1本试验方法旨在测量热固性塑料在规定条件下通过压缩、注射或转移成型时从模腔到成型尺寸的收缩率。 1.2本试验方法提供了热固性塑料从其模具开始（成型后16至72小时内）和老化后（高温下的后收缩）的收缩测量。 1.3该方法将给出基于标准试样的可比数据，并且无法预测具有不同流动路径、壁厚、压力梯度和工艺条件的实际模制零件中的绝对值。本试验方法中描述的试样几何形状之间通常观察到模具收缩的差异。 1.4塑料初始收缩的知识对于模具的建造很重要，而模塑后收缩的知识对于确定模塑材料是否适合制造尺寸精确的热固性塑料部件很重要。 1.5以国际单位制表示的数值应视为标准值。括号中给出的值仅供参考。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 注1 — 本试验方法和ISO 2577-1984 当使用长度为120 mm、宽度为15 mm、厚度为10 mm的棒材进行压缩成型时，其等效性相当；或约120×120×4 mm的扁平方形板用于注塑成型。 ====意义和用途====== 4.1 压缩成型- 在压缩模塑中，模具尺寸与由给定材料在其中生产的模塑制品尺寸之间的差异因模具的设计和操作而异。当设计和操作使得最大材料被牢固地压入模具型腔或其部分时，或者当模塑制品在仍承受压力的情况下（尤其是通过冷却）硬化到最大时，收缩率很可能会接近最小值。 相反，当电荷必须在模腔中流动，但没有接收和传递足够的压力以牢固地压入其所有凹槽，或者当释放时模塑制品未完全硬化时，收缩率较高。所用材料的塑性会影响收缩，因为它会影响装料的保留和压缩。 4.2 注塑成型- 在注射成型中，与在压缩成型中一样，根据模具的设计和操作，模具和由给定材料在其中生产的模制品的尺寸之间的差异会有所不同。这些差异取决于成型机的类型和尺寸、成型截面的厚度、模具中材料的流动或移动程度和方向、喷嘴、浇口、流道和浇口的大小、机器运行的周期、模具的温度以及随后的时间长度- 保持上升压力。在压缩成型的情况下，收缩将接近最小值，在设计和操作中，最大限度的材料被牢固地压入模腔，并且由于使用了适当尺寸的流道、浇口和喷嘴以及适当的停留时间，模压制品在仍然承受压力的情况下被硬化到最大值。与压缩成型一样，当填充料必须在模具型腔中流动，但无法接收和传递足够的压力以牢固地压入模具的所有凹槽时，收缩率更高。所用材料的塑性间接影响收缩，因为更容易塑化的材料将需要较低的成型温度。 4.3 转移模塑- 在转移模塑中，如在压缩或注射模塑中，根据模具的设计和操作，模具和由给定材料在其中生产的模塑制品的尺寸之间的差异不同。 它受锅或圆筒的尺寸和温度、压力以及模具温度和成型周期的影响。流动方向不是一个重要的因素。 4.4 材料标准- 成型前的特殊处理、成型条件和成型后试样的特殊处理始终参考材料标准。如果材料标准不可用，请联系制造商以获取这些建议。 4.5 实用程序- 测量从模具到模压尺寸的初始收缩的批次间一致性有助于评估热固性塑料的质量。

1.1 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. 1.2 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). 1.3 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. 1.4 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. 1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.6 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. ====== Significance And Use ====== 4.1 Compression Molding— In compression molding, the difference between the dimensions of a mold and of the molded article produced therein from a given material vary according to the design and operation of the mold. It is probable that shrinkage will approach a minimum where design and operation are such that a maximum of material is forced solidly into the mold cavity or some part of it, or where the molded article is hardened to a maximum while still under pressure, particularly by cooling. In contrast, shrinkages are higher where the charge must flow in the mold cavity but does not receive and transmit enough pressure to be forced firmly into all its recesses, or where the molded article is not fully hardened when discharged. The plasticity of the material used affects shrinkage insofar as it affects the retention and compression of the charge. 4.2 Injection Molding— In injection molding, as in compression molding, the differences between the dimensions of the mold and of the molded article produced therein from a given material vary according to the design and operation of the mold. The differences vary with the type and size of molding machine, the thickness of molded sections, the degree and direction of flow or movement of material in the mold, the size of the nozzle, sprue, runner, and gate, the cycle on which the machine is operated, the temperature of the mold, and the length of time that follow-up pressure is maintained. As in the case of compression molding, shrinkages will approach a minimum where design and operation are such that a maximum of material is forced solidly into the mold cavity and where the molded article is hardened to a maximum while still under pressure as a result of the use of a runner, sprue, and nozzle of proper size, along with proper dwell. As in compression molding, shrinkages are higher where the charge must flow in the mold cavity but does not receive and transmit enough pressure to be forced firmly into all of the recesses of the mold. The plasticity of the material used affects shrinkage indirectly, in that the more readily plasticized material will require a lower molding temperature. 4.3 Transfer Molding— In transfer molding, as in compression or injection molding, the difference between the dimensions of the mold and of the molded article produced therein from a given material vary according to the design and operation of the mold. It is affected by the size and temperature of the pot or cylinder and the pressure on it, as well as on mold temperature and molding cycle. Direction of flow is not as important a factor. 4.4 Materials Standards— Always refer to material standards for special treatment prior to molding, molding conditions and special handling of the test specimens after molding. In the event the material standard is unavailable, contact the manufacturer for these recommendations. 4.5 Utility— Measurement of batch-to-batch consistency in initial shrinkage from mold to molded dimensions is useful for evaluating the quality of thermosetting plastics.