Several factors can affect the accuracy of castings produced by investment casting which include:
Wax injection molding: Wax injection molding is a critical process for creating the desired shape of the casting. The proper injection molding process must create a wax pattern with the exact dimensional accuracy needed for the final casting. If the wax pattern is inaccurate, it will cause problems in the final casting.
Shell building: The shell building process is significant as it creates the mold that holds the metal that forms the finished casting. It is necessary to ensure that the shell thickness, coverage, and surface properties of the mold, are kept at an optimal level, and free from cracks or defects.
Casting Temperature: Maintaining the correct casting temperature ensures the metal alloys used in investment casting remain sufficiently liquid, and that metal is distributed accurately throughout the mold cavity.
Pouring Process: The pouring of the molten metal into the mold must be done with precision to produce high-precision castings. If not done with precision, it can also lead to other defects such as misalignment of the core, variation of wall thickness, among others.
Cooling Process: The casting mold must be steadily cooled after the casting process. This should be done at the right rate to minimize any residual stresses that can lead to casting deformations or warping.
Post-Casting Processing: Post-casting processing such as cutting, grinding, and polishing of the casting to achieve the final dimensions may lead to dimensional variations if not carried out with precision. The casting's surface finish may also be compromised if the process is not well controlled.
Overall, investment casting requires strict control, adherence, and precision in each production step to produce high accurate castings. Investment casting foundries must deliver the best overall process control using modern equipment, technology, and quality assurance to maintain high-quality specifications that facilitate high precision castings.