Investment casting, also known as lost wax casting, has been successful in creating near net shapes for thousands of years. While the process has significant advantages in its ability to create complex geometry with relatively tight tolerances, it requires that a tool be created to mold wax patterns. The substantial cost and time required to generate wax pattern tooling limits the range of applications for which investment casting is economically competitive.
In recent history, “Direct Cast Patterns,” produced with Rapid Prototyping (RP) technology, have afforded the investment casting industry a boost by allowing more designs to be cast without the initial expense and time to fabricate wax pattern tooling. Direct Cast
Patterns may be defined as investment casting patterns created without the use of tooling to create the pattern shape. Many RP technologies are capable of creating a direct cast pattern. However, only Stereolithography provides the dimensional accuracy and surface finish required for the majority of production investment castings. Consequently, direct casting patterns made with stereolithography are the most common and most widely accepted in the investment casting industry. SL produces a mostly hollow style pattern with an internal honeycomb structure. Can be used in place of a wax pattern. This hollow build style is important, as it allows the pattern to collapse inward during the autoclave and shell burnout phases of the casting process and thus prevents expansion forces from cracking the shell. The mostly hollow build style also reduces the amount of material necessary to burnout.
The purpose of this guide is to assist foundries to successfully cast QuickCast patterns. While earlier guides from Express Pattern provided general recommendations, recent improvements in both SL technology and resins have made it possible to minimize the number of specialized processing steps required to successfully cast QuickCast patterns. This guide includes the most recent information on processing QuickCast patterns and will be updated frequently as new information becomes available.
Please note that the recommendations put forth in this document are guidelines and may need to be modified by the individual foundry based on their processes and equipment.