Investment Casting: how does it work and develop?

Mar 2022

Investment Casting: how does it work and develop?

   How Does Investment Casting Work?

investment casting

If you are stuck in taking an investment casting decision, then this article is for you.


Several manufacturers use the casting process to produce sustainable products. These products are then used in various applications.


As compared to other casting processes like sand casting, investment casting includes the manufacturing of highly accurate and intricate products.


According to Global investment casting market research, casting will grow around 5% during 2022-2026.


This means more and more companies are going to manufacture casting products and thus the market will grow eventually.


Now, before we move to the main topic, let’s get an idea of what investment casting is?


What is Investment Casting?


Lost wax casting, also known as investment casting, is the method of producing precise products. The products will then use in the military, medical, and various other applications.


The term investment comes from investing which means surrounding. So, this method involves a manufacturing process in which a ceramic mold surrounds a wax pattern.


The wax pattern has a coating of refractory material and it obtains the shape which needs to be cast for the final product. The shell becomes hard which is then melted and converted into a mold. Mold breaks and you will get the final product successfully.


Why is the Investment Casting Method Better than Others?


Various other cast manufacturing processes such as sand casting can also make the mold or final product. However, lost wax casting or investment casting methods are most commonly used. The reason lies in its unique features which are as follows:


  • Unlike other methods, it produces highly accurate and precise components hence also known as precision casting.


  • The casting of extremely complex and intricate products are achieved easily with this method.


  • Its short length and highly in-depth features can cast objects of even 0.40mm thickness.


  • With a high tolerance of 0.075mm, it provides excellent dimensional precision of the objects.


As if that’s not enough, so let’s break down the investment casting production process into the following steps for your better understanding:-


How Does Investment Casting Work?

For thousands of years, investment casting prepared different near-net shapes and precise objects.


Moreover, with the invention of the latest technology and new manufacturing tricks, lost wax casting has improved a lot and involves the following steps of production:-


1- Creation of Master Pattern


First of all, prepare a master pattern to initiate the process. Wax, clay, steel, or any other material can create a master pattern.


Then, according to the desired shape of the final product, finalize a pattern. You can create it manually or with the help of mold maker machinery.


After omitting the errors and malfunctions, a final shape of the product will form successfully.


2- Preparation of Mold


To produce copies of the wax pattern, you need to create a mold also known as a master die. You can produce this die with machining tools easily.


However, if your wax pattern is of steel material, then you should prepare the mold directly from the steel master. The number of molds depends on the number of casting products you need.


Then, align the prepared molds in two halves, so that precise parts produce without separating the lines.


3- Pouring and Hardening


The produced mold pattern is then poured into the ceramic shell. After pouring the molten wax into the master pattern, cover it with sand stucco and allowed to dry.


The coating process repeats until you get the required thickness ranging about 3mm. The dimensions and configuration of the final product are then adjusted following this thickness.


4- Assembly of the Pattern


The shell is then heated, the wax pattern melts away and the hard shell turns into a hollow ceramic shell.


Onto a wax sprue, these wax patterns are then assembled. With the help of heating tools, all the wax patterns are then attached with a central sprue. This makes a tree-like arrangement or an assembly of wax patterns.


5- Dipping the Wax


The main purpose of dipping the wax pattern is to produce a prime coat. For this, dip the pattern into a refractory material so a uniform coating surface forms.


This involves the production of a very thin and smooth layer so a delicate and accurate final product forms, and this is the key to precision casting.


At this stage of investment casting, you’ll get the layers, then dry the first or initial layer so the strength will enhance further.


This will increase the hardness and strength of the final product and then the leftover will dry completely.


6- De-waxing


After the wax material has dried completely, it puts into a de-waxing autoclave or simply in an oven to initiate the melting process.


Just after you put the wax material into the autoclave, it starts melting and the residues begin to vaporize quickly. This is the de-waxing of the prepared wax material.


The most important thing to note down is, this is the most crucial stage of the investment casting process. This is because any error in it will affect your yield production.



7- Heating the Mold


Once the dewaxing process completes, heat the mold at about 90oC to 175oC so it heats effectively. This preheating process may take up to 3-4 hours.


Then an elevated temperature is maintained and the residual wax is burnt off. Pre-heating of the mold is done to increase the accuracy of the casting product and smooth the production method.

8- Solidification and knock-out


With the help of hammering, and different techniques, solidify the metal, break it down and cut down the excess material.


Sprue the sprue and the final product obtains successfully with accurate shape, and size.




In the end, investment casting or precision casting is a simple method that completes with the following discussed 8 steps.


However, recent advancements in the field of casting and the latest technologies make the casting process easier.


3D printing technologies, laser jetting, modeling technologies, and various other technical methods are now used to create patterns with a good surface finish.