Investment Casting
Investment casting is a manufacturing process in which a wax mold is coated with a refractory ceramic material. Once the ceramic coating material has dried and hardened, the wax melts and leaves the final product geometry in the internal cavity. Molten metal is poured into the cavity where the wax mold is located. The metal solidifies in the ceramic cavity, cools, and then the ceramic is removed from the metal casting. The result of this process is net-accurate to near-net-accurate metal parts that can be used in a wide range of applications in a variety of industries.
The process of investment casting
Investment casting is a manufacturing process in which a liquid material is poured into a ceramic mold that contains a cavity of the desired shape and then allowed to solidify. The solidified part is the casting, which is removed from the ceramic mold to complete the process. The steps in the investment casting process are as follows:
Step 1: Engineering Review
The first step in the manufacturing process is a complete Design for Manufacturing (DFM) review with the customer.
This will include an evaluation of the print dimensions associated with the investment casting process, wax injection pattern build considerations (e.g., gate locations), backshell material requirements and expected tolerances for part fit, form and function, and final inspection criteria to determine a mutually acceptable part.
Step 2: Mold Design and Fabrication
The process begins with a precision-designed wax injection mold to produce a wax mold representative of the final part.
These design considerations are discussed with the mold maker and a mold design is created.
Molds are designed and built to replicate millions of wax parts over their lifetime.
Shell Mold Casting
Shell casting is a metal casting process similar to sand casting, in which molten metal is poured into a disposable sand mold. However, in shell casting, the mold is a thin-walled shell made by applying a sand resin mixture around the model. The model is a piece of metal with the desired part shape that can be reused to form multiple shell molds. Reusable models increase productivity, while disposable molds allow for the casting of complex geometries.
The process offers greater dimensional accuracy, higher productivity, and lower labor requirements than sand casting, and is often used for small to medium-sized parts with high accuracy requirements.
Shell casting is suitable for ferrous and non-ferrous metals. The most commonly used are carbon steel, alloy steel, stainless steel and copper alloys. Typical parts cast using this process are small to medium in size and require high accuracy, such as gearboxes, cylinder heads, connecting rods and lever arms.
Stainless Steel Investment Casting
Stainless steel investment casting, also known as investment casting or lost wax casting, is a manufacturing process used to make complex metal parts of various shapes and sizes. The process involves pouring molten stainless steel into a ceramic shell or mold that is made by coating a wax mold with a ceramic material.
Concepts and Characteristics of Stainless Steel
Stainless steel is a chromium-containing iron alloy that provides a protective coating against fouling and corrosion. It performs well in liquid environments and is heat resistant at elevated temperatures. There are many different types of stainless steel, each containing a different chemical composition. The composition affects the mechanical properties and determines whether the material can be further strengthened by heat treatment.. They are widely used in aerospace, automotive manufacturing, chemical equipment, medical devices, and other fields.
Carbon Steel Investment Casting
Carbon steel is a steel alloy with carbon as the primary alloying element. Cast alloy steels have been developed for use in conditions requiring higher pressure, wear resistance and higher strength, as well as higher toughness and hardenability. The mechanical properties of this alloy are determined by the percentage of carbon; the higher the percentage, the harder and stronger the alloy becomes through heat treatment. Because carbon steel can be machined to obtain a variety of properties, it can be used in a variety of applications.
Both medium and low carbon steels are used in investment casting. Medium carbon steel has good ductility, strength and wear resistance. It can also be hardened and tempered by heat treatment. Mild steel is easy to form but cannot be strengthened by heat treatment. As an alternative, carburizing can be used to increase the surface hardness of the alloy.
