1.1 本规范涵盖热塑性塑料（例如颗粒、丸粒）和用于制备试样的研磨原料的压缩成型。 2 附注1: 某些ASTM标准要求在 附件A1 用于聚乙烯试样的压缩成型。 1.2 虽然给出了某些材料的条件，但具体条件的主要来源应是每种材料的材料规格标准。 1.3 单位- 以SI单位表示的值将被视为标准值。 1.4 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。附注2: ISO 293:2023已更新，不再等同于ASTM D4703。该做法被认为在技术上类似于ISO 293:2023，但在细节上有所不同。 列出了ISO 293-1986和ASTM的区别 D4703 -16:主体 D4703 -16相当于ISO 293-1986。附录A1和ISO 293-1986在一些细节上有所不同；然而，使用 附件A1 程序A应等同于使用ISO 293-1986，冷却方法D制备的样品 附件A1 程序C应等同于使用ISO 293-1986，冷却方法B制备的程序。然而，由于ISO标准的冷却速率公差较大，根据ISO冷却方法B制备的样品可能不等同于 附件A1 ，程序C。 1.5 本国际标准是根据《关于制定国际标准的原则的决定》中确立的国际公认的标准化原则制定的des和世界贸易组织技术性贸易壁垒(TBT)委员会发布的建议。 ======意义和用途====== 4.1 制备和模制样品材料的方法影响样品的机械性能。与注射成型不同，压缩成型的目的是生产既均匀又各向同性的试样或片材。样品可以由粉末或粒料(例如直接从材料制造商接收)、在再循环回收操作中产生的颗粒、或由在双辊研磨机上制备的研磨的预成型件或片材成型。粉末、粒料、颗粒、预成型件或片材在设计用于生产给定几何形状、尺寸和厚度的成品样品的模具中熔融和模制，或者熔融和模制为均匀厚度的光滑板或片材，从中切割、冲压或机加工所需样品。在模制之前在双辊轧机上加工化合物将以影响化合物物理性质的方式分散和分布化合物添加剂。应咨询相关材料规范或材料制造商，以确定在压缩成型前是否需要铣削样品。以相同的方式处理相同类型材料的不同样品是很重要的:如果在将用作比较标准的材料上模制之前进行了铣削，则应以类似的方式制备和模制所有根据该实践进行测试的新材料。 4.2 制备足够样品所需的设备和确切条件通常会因每种塑料材料而异。在本实施例中分节给出了用于模制许多不同塑料材料的令人满意的设备和程序 5和 6 附录中给出了已被发现对某些特定材料的成型令人满意的设备和程序。在任何情况下，用于生产给定材料的压缩成型样品的具体设备和程序应参考相关材料规范或通过买方和供应商之间的协议获得。

1.1 This practice covers the compression molding of thermoplastics (for example, granules, pellets) and milled stock for the preparation of test specimens. 2 Note 1: Certain ASTM standards require the use of Procedure C in Annex A1 for compression molding of polyethylene test specimens. 1.2 While conditions for certain materials are given, the primary source of specific conditions shall be the material specification standards for each type of material. 1.3 Units— The values stated in SI units are to be regarded as standard. 1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Note 2: ISO 293:2023 has been updated and is no longer equivalent to ASTM D4703. The practice is considered technically similar to ISO 293:2023 but differs in detail. Listed are the differences between ISO 293-1986 and ASTM D4703 -16: The main body of D4703 -16 is equivalent to ISO 293-1986. Annex A1 and ISO 293-1986 differ in some details; however, specimens prepared using Annex A1 , Procedure A should be equivalent to those prepared using ISO 293-1986, Cooling Method D. Specimens prepared using Annex A1 , Procedure C should be equivalent to those prepared using ISO 293-1986, Cooling Method B. However, due to the greater cooling rate tolerances of the ISO standard, specimens prepared in accordance with ISO Cooling Method B may not be equivalent to Annex A1 , Procedure C. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 The methods by which sample materials are prepared and molded influence the mechanical properties of the specimen. Unlike injection molding, the objective of compression molding is to produce test specimens or sheets that are both homogeneous and isotropic. Specimens can be molded from powder or pellets such as are received directly from a material manufacturer, particles produced in a recycle recovery operation, or from a milled preform or sheet prepared on a two-roll mill. The powder, pellets, particles, preform, or sheet are melted and molded in a mold designed to produce a finished specimen of a given geometry, size, and thickness, or melted and molded in the form of a smooth plaque or sheet of uniform thickness from which desired specimens are cut, punched, or machined. Working a compound on a two-roll mill prior to molding will disperse and distribute the compound additives in a manner that will affect the physical properties of the compound. The relevant material specification or the material manufacturer shall be consulted to determine the need for milling a sample prior to compression molding. It is important to treat different samples of the same type of material in the same way: if milling was done prior to molding on a material which is to be used as a standard for comparison, all new materials to be tested against this practice shall be prepared and molded in a similar manner. 4.2 The apparatus and exact conditions required to prepare adequate specimens will usually vary for each plastic material. Apparatus and procedures satisfactory for molding many different plastic materials are given in this practice in Sections 5 and 6 . The apparatus and procedures which have been found satisfactory for molding certain specific materials are given in the Appendixes. In any case, the specific apparatus and procedures to be used in producing compression-molded specimens of a given material shall be obtained by reference to the relevant material specification or by agreement between the purchaser and the supplier.