1.1 本规程涵盖了热固性材料注塑试样时应遵循的一般原则。它用于在描述注塑过程的各个步骤的方法和这些条件的报告中获得一致性。具体的成型条件因材料而异，如果未包含在材料规范中，则应由买方和供应商商定，或根据之前使用的特定类型材料及其塑性的经验确定。 注1: 该实践已被证明适用于表现出较低性能的热固性模塑化合物的模塑- 粘性非牛顿流。 1.2 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。 1.3 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、健康和环境实践，并确定监管限制的适用性。 1.4 本规程假设使用往复式螺杆注塑机。 注2: 本标准和ISO 10724涉及相同的主题，但技术内容不同。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 本实践以中给出的注射成型定义为准 3.1.2 进一步规定，通过直列螺杆注射，通过传导和摩擦在腔室中加热的塑料化合物通过往复螺杆的作用流动，然后强制进入热模具中固化。 以下，直列螺杆注射成型将简称为注射成型。 4.2 本节中引用的模具（参见 图1 )通常是有用的，并描述了测试热固性塑料所需的最常见样本。然而，ISO样本和测试正在获得青睐。实践 D3641 和ISO 10724描述了根据ISO对多用途试样进行注射成型的布局和做法 3167 图1 热固性塑料试样的五腔转移模（未显示蒸汽芯） 注1: 温度计套管应为8 mm( 5. / 16 英寸。）直径允许使用现成的温度计。 4.3 通常，注塑试样的周期比通过压缩制成的类似模塑件的周期短，并且该周期等于或快于转移模塑的周期。 4.4 由于气体可以从模具的通风端自由流动，因此通常不需要呼吸模具来释放截留的挥发性物质。这对耐热化合物特别有利，并减少模制试样在高暴露温度下起泡的趋势。 4.5 注射成型用于低粘度化合物。不能为所有类型的热固性材料或具有不同塑性的相同材料的样品指定一组处理参数。 4.6 含有纤维填料（如玻璃粗纱、短切布或纤维素纤维）的材料可以注塑成型，但其性能将受到影响，这取决于当化合物通过螺杆加工以及通过流道和浇口系统时，纤维分解的程度。模压试样中纤维的方向也会影响注塑性能。 4.7 模塑件中的流线和编织线通常是机械或电气薄弱部位。通过浇口的熔剂材料在进入模具型腔时会起皱和折叠。针织线在一定程度上贯穿整个模塑件； 并且会影响测试结果。模塑料中的纤维和其他增强材料与流型对齐，通常在其中心垂直于杆的轴，在其表面平行。 4.7.1 浇口和通风口的位置和尺寸可用于最小化流动和编织线，例如，当材料前沿穿过模具长度时，棒的侧浇口将最小化材料自身折叠的趋势。 4.8 含有短纤维的注塑试样的Izod冲击强度通常低于使用压缩成型方法获得的值。 由于成型参数、流型和纤维方向的不同，冲击强度也可能沿棒轴变化。 4.9 含有短纤维的模塑化合物的注塑试样的弯曲和拉伸强度通常高于使用压缩成型方法获得的值。弯曲试验对注射成型特别敏感，因为在最终填充型腔和压力累积期间，棒材表面形成了薄树脂皮。 4.10 在恒定的模具温度下，已知以下参数会导致型腔通风端出现填充不足的情况: 塑性不正确、注射压力过低、材料不足、注射时间过长、通风口堵塞、坯料温度过高或模具温度不正确。

1.1 This practice covers the general principles to be followed when injection molding test specimens of thermosetting materials. It is to be used to obtain uniformity in methods of describing the various steps of the injection molding process and in the reporting of those conditions. The exact molding conditions will vary from material to material, and if not incorporated in the material specification, shall be agreed upon between the purchaser and the supplier or determined by previous experience with the particular type of material being used and its plasticity. Note 1: The utility of this practice has been demonstrated for the molding of thermosetting molding compounds exhibiting lower-viscosity non-Newtonian flow. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.3 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. 1.4 This practice assumes the use of reciprocating screw injection molding machines. Note 2: This standard and ISO 10724 address the same subject matter, but differ in technical content. 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 This practice is subject to the definition of injection molding given in 3.1.2 with the further provision that with in-line screw injection the plastic compound, heated in a chamber by conduction and friction, is fluxed by the action of a reciprocating screw and then is forced into a hot mold where it solidifies. Hereafter, in-line screw-injection molding will be referred to simply as injection molding. 4.2 The mold referenced in this section (see Fig. 1 ) is generally useful, and describes what have been the most common specimens required for the testing of thermosets. ISO specimens and testing are gaining favor, however. Practice D3641 and ISO 10724 describe the layout and practice for injection molding the multi-purpose specimens in accordance with ISO 3167. FIG. 1 Five-Cavity Transfer Mold for Thermosetting Plastic Test Specimens (Steam Cores Not Shown) Note 1: Thermometer wells shall be 8 mm ( 5 / 16 in.) in diameter to permit use of a readily available thermometer. 4.3 Typically, injection-molded test specimens are made with shorter cycles than those used for similar moldings made by compression, and the cycle is equal to or faster than that for transfer molding. 4.4 Breathing of the mold is not usually required to release trapped volatile material as the gas is free to flow from the vent end of the mold. This is particularly advantageous for heat-resistant compounds and reduces the tendency for molded specimens to blister at high exposure temperatures. 4.5 Injection molding is intended for low-viscosity compounds. One set of processing parameters cannot be specified for all types of thermosetting materials, nor for samples of the same material having different plasticities. 4.6 Materials containing fibrous fillers such as glass roving, chopped cloth, or cellulosic fibers can be injection molded, but their properties will be affected depending upon how much fiber breakdown occurs as the compound is worked by the screw and as it passes through the system of runners and gates. The orientation of the fibers in the molded specimen will also affect injection-molded properties. 4.7 Flow and knit lines in a molded piece are often sites of mechanical or electrical weakness. The fluxed material passing through the gate wrinkles and folds as it proceeds into the mold cavity. Knit lines are found to some degree throughout the molded piece; and can affect test results. Fibers and other reinforcements in the molding compound align with the flow pattern and, generally, are perpendicular to the axis of the bar at its center and parallel at its surface. 4.7.1 Placement and size of gates and vents can be used to minimize flow and knit lines, for example, side gating of bars will minimize the tendency of the material to fold onto itself as the material front proceeds through the length of the mold. 4.8 The Izod impact strength of injection-molded specimens containing short fibers will generally be lower than the values obtained using compression molding methods. The impact strength can also vary along the axis of the bar due to molding parameters, flow patterns, and fiber orientation. 4.9 The flexural and tensile strength of injection-molded specimens of molding compounds containing short fibers will generally be higher than the values obtained using compression-molding methods. Flexural tests are particularly sensitive to injection molding due to the thin resin skin formed at the surface of the bar during final filling of the cavity and pressure buildup. 4.10 At constant mold temperature the following parameters are known to cause an underfilled condition at the vented end of the cavity: incorrect plasticity, too low an injection pressure, insufficient material, too long an injection time, blocked vents, high stock temperature, or incorrect die temperature.