SBIR Phase I: Development of a Metal Aggregate Rapid Tooling Process for Casting Aluminum Alloys

这个小企业创新第一阶段研究项目旨在开发一种新型快速模具材料，用于低成本生产小批量和原型铸件。这种快速模具材料提供了典型的砂型成型的易用性，但在性能和性能上可与金属永久模具相媲美。模具包括带有硅酸盐粘结剂的金属骨料，经过热处理以达到适当的硬度和尺寸稳定性。该项目将解决以下问题：(1)制造复杂的模具；(2)模具材料的表征；(3)用该模具生产的铸件尺寸精度和表面粗糙度分析；(4)铸铝在模具中凝固冷却速率的测定；(5)模具抗热疲劳性和耐久性评价；(6)确定用这种方法制造快速模具的交货时间；在这些模具中制造的铸件有望更快地冷却，从而获得更高的极限强度，延展性和伸长率。此外，由于枝晶臂间距更细，预计在热处理过程中均匀化时间更短。这些特性使这种材料不仅对快速模具有吸引力，而且对砂型铸造中的轮廓冷却也有吸引力。这些将用于增加从铝凝固中局部提取热量，从而改善铸件关键部分的机械性能。这个项目更广泛的（商业）影响将是金属集料模具技术，使其能够快速和廉价地形成原型开发铸件的模具。所生产的模具在重力永久模具、低压压铸和注塑塑料零件等金属模具铸造工艺中具有潜在的应用前景。金属骨料最明显的商业应用是小体积、高强度铝铸件的模具。作为永久模具，金属集料模具提供整体通风，消除了机械制造通风口的需要，从而节省了时间和成本。金属集料的另一个潜在应用是制造砂型铸造用型钢。作为一种可塑材料，金属骨料适合形成导热模具的模式，否则不容易实现。该公司的主要产品是铝制叶轮，采用永模和砂模相结合的工艺制造。在铸造过程中被永久模具困住的芯气是造成缺陷的主要原因，导致废品率超过5%。耐用、可渗透的工具可以大大降低工具成本，从而更快地实现叶轮创新，从而实现更节能的制冷设计。

This Small Business Innovation Phase I Research project aims to develop a novel rapid tooling material for inexpensive production of low volume and prototype castings. This rapid tooling material offers the ease of molding typical to sand molding yet is comparable in properties and performance to metallic permanent molds. The mold comprises a metallic aggregate with a silicate binder, thermally processed to achieve appropriate hardness and dimensional stability. The project will address the following: (1) manufacturing of a complex mold; (2) characterization of the mold material; (3) analysis of the dimensional accuracy and surface roughness of castings produced with this mold; (4) determination of the cooling rates during solidification of aluminum cast in the mold; (5) evaluation of the thermal fatigue resistance and durability of the mold; (6) determination of the lead time to fabricate rapid tooling by this method; Castings made in these molds are expected to cool faster resulting in higher ultimate strength, ductility and elongation. In addition, because of the finer dendrite arm spacing, a shorter homogenization time during heat-treating is anticipated. These attributes make this material attractive not only for rapid tooling but also for contoured chills in sand casting. These would be used to increase local extraction of heat from solidifying aluminum, thereby improving mechanical properties in critical sections of the casting.The broader (commercial) impact from this project would be a metallic aggregate mold technique that lends itself to rapid and inexpensive forming of molds for prototype development castings. The mold so produced has potential applications in metal mold casting processes such as gravity permanent mold, low pressure and die-casting and injection molded plastic parts. The most apparent commercial application for the metal aggregate is in molds for low volume, high strength aluminum castings. Used as a permanent mold the metal aggregate mold provides integral venting, eliminating the need for mechanically created vents thus saving time and cost. Another potential application of the metal aggregate material is in manufacturing of shaped chills for sand casting. As a moldable material the metal aggregate fits the pattern to form a thermally conductive mold otherwise not readily achievable. The company's principal product is aluminum impellers made by a process, which utilizes a combination of permanent and sand molds. Core gases trapped by the permanent mold during the casting process are a major cause of defects, resulting in scrap rates in excess of five percent. A durable, permeable tool could substantially reduce that tooling cost, leading to more rapid implementation of impeller innovations, hence more energy efficient refrigeration designs.