Steel is vital metalwork for many industries and its casting is an important process to cater and fit it in the desired shape. Due to its less fluidness and more reactivity towards other mold materials, its casting is a difficult process. Hence, it should be done by trained metalworkers for gaining optimized performance of components.
Investment casting also called lost-wax casting or precision casting is a process used for shaping ceramic mold. A wax pattern is initially generated which has the same shape as the desired shape into which steel is to be cast. The wax pattern is covered with ceramic material. When the ceramic materials dry and solidify, it is inverted onto a heating source until it melts and gets separated. This solid shell serves as a disposable investment mold. The metal which is in the molten state is pelted into the mold and left until it dries. Finally, metal casting is broken from the used mold. This method has been used for hundreds of years hence it has a long production history. Investment casting is a useful process for the creation of complex components and parts. It involves a number of steps for designing and creating the workpieces. The workpieces are created in shelled casting, and it is removed when poured workpieces are set.
The steel investment casting process is the most widely used molding method as it produces very fine-quality products and excellent casted surfaces which can also be cast with thin well and complicated passageways. Moreover, it does not need a draft as in sand casting. It can also be used to produce net casting or near-net-shaped castings which make this method the most material, machine, and labor-saving method. It can produce the most commonly used metals including stainless steel and carbon steel. Turbine blades, firearm components, jewelry, gears, golf club heads, medical equipment, and machine components having complicated geometry are some examples of parts manufactured by the investment casting process.
Steps Involved In Steel Investment Casting:
Following steps are involved in investment casting:
Firstly, a pattern or die which is made from wax is created for the desired workpiece. Then, this wax pattern will be set up as a wax assembly for large-scale production as small-scale production at a time is not economically beneficial. After wax tree creation, a ceramic sheet is needed to be built around the wax tree. After that, the wax is removed either by using a Steam-dewax autoclave machine or flashfire ovens. Next, the shell is heated at a particular temperature to avoid the hardening or solidification of the shell during the process of injection. When the ceramic cup is melted, it is pelted into the shell. Then the shell is removed by any of these 3 methods: High-Pressure Water Blast, Vibratory Table, Hammer. After the shell has been removed from the tree, the part is cut from the sprue and gate ground. Lastly, the casting process is finished by belting, grinding, or polishing.
Advantages of investment casting method
Investment casting is a very advantageous method of metal casting as it produces a very good surface finishing, It has high accuracy in terms of dimensions. It can help in casting complicated parts very easily. Almost every metal can be cast using this method. It produces no parting lines or flash. It enables effective metal utility. It is an environment and health-friendly casting method.
Disadvantages of investment casting method
Its main disadvantage is that this method is very costly for small-scale production. It needs specialized equipment, binders, costly refractories, molding operations, and manual labor. Occasionally minor defects may occur. It is difficult to cast objects which need cores by this method. This method is suitable for holes smaller than 1.6 mm and less deep than 1.5x the diameter. It needs a long cycle for production as compared to other casting methods. Many process factors can affect the mold and casting quality, so achieving quality is a challenging task and depends on the skills of the manufacturer. The dies used for pattern making are very costly.
In this article, the steel investment casting process is discussed, Moreover, an overview of the steps involved, advantages, and disadvantages are also presented.