The biggest advantage of Investment Casting is that because of the high dimensional accuracy and surface finish of the investment casting, it can reduce the machining work, but only a small amount of machining allowance is required on the parts, even some castings only Leave the grinding and polishing allowance and use it without machining. The investment casting method can save a lot of working time of machining equipment and greatly save metal raw materials.
There are many factors affecting the dimensional accuracy of castings, such as shrinkage of the molding material, deformation of the investment mold, variation in the amount of the shell during heating and cooling, shrinkage of the alloy, and deformation of the casting during solidification, plus Casting large-size products is prone to fission problems, and investment casting is a technique + experience.
Headquartered in the United States, Alliant Casting is a long-established foundry that recently challenged the printing of ABS materials for large-scale investment casting through FDM technology. This opens up the imagination for ABS, an economical and popular engineering plastic, to enter into industrial-scale large-scale parts by 3D printing.
Image: Castings without any thermal cracking defects
Solve thermal expansion and thermal cracking defects
Founded in 1885, Alliant foundry has long provided its customers with excellent castings thanks to Alliant Casting's continuous innovation in casting technology. Recently, this century-old foundry introduced 3D printing technology into the casting process, which significantly reduced the cost of casting and significantly shortened the casting cycle.
In order to solve the investment casting needs of large parts, the 3D printer used by Alliant is the Altas 2.0 FDM 3D printer of Tian 3D Robotics. The main task of this 3D printer is to perform 3D printing of the investment mold. The Altas 2.0 3D printer has a build space of 915 x 915 x 1220mm.
Image source: 3ders
Prior to the purchase of the Altas 2.0 3D printer, Titan 3D printed an ABS investment mold for the Alliant foundry 3D, which took 12 hours. The 3D printed ABS investment mold will be used as the investment master in the Lost Wax Casting process after being delivered to the foundry. The foundry will coat the refractory material for the master mold and obtain the shell after burning the mold, and finally pass the sand mold. Casting of metal parts. The total time taken from molding to the completion of casting of metal parts is 2 working days, and the loss of wax casting by the conventional process requires first to manufacture a welding mold through a mold, and merely the manufacture of the investment mold is a cumbersome process.
Of course, we know that the ABS thermal expansion rate is 0.35% at 100 degrees Celsius, and then remains stable, starting to liquefy at 125 degrees. How to ensure the problem of rising shells in the investment casting process, which also needs to be considered in the process of 3D printing modeling. Through 3D printing technology, Alliant was able to complete the casting work that took two weeks to complete in less than 24 hours, and the casting cost dropped from $35,00 to $1,300.
Image source: 3ders
In addition to the thermal expansion of the material, the investment mold is prone to thermal cracking defects in the casting applications of large parts. Alliant foundries face the same challenge when using large-size investment castings for casting, and with the know how many years of accumulation, Alliant successfully overcome this problem. Therefore, the application of driving 3D printing technology is not only the 3D printing technology itself, but also the deep integration of experience in the application field to realize its commercial value.
In addition, Alliant has gradually developed more applications in the field of casting for FDM 3D printing technology, such as the application of ABS 3D printing parts with good mechanical properties and heat resistance to the die casting process of large parts, 3D The printed PLA parts are used in the lost foam casting process and in the self-hardening molding process for small parts.
(Editor)
