Stainless steel casting is often used in situations where other materials would not last for long. This is because it resists corrosion. Making a new shape of metal can be challenging. You have to heat the metal up and then pour it into a mold that has been designed for that shape. Castings are usually made from stainless steel, which is heated until it melts and then poured into a mold with the right shape. This article is about how to make steel. We will focus on the process of stainless steel casting.
- Mould Preparing
Mould for stainless steel casting is designed to the shape of the product. Usually, there are two cast molds that are filled with metal. One is turned into an upper concave mold, and the other will be a lower concave mold. After this, it is carefully machined so that it matches the shape of the stainless steel part. It is not easy to make a wax model. Sometimes you need to use aluminum when making the mold for the casting. Aluminum has a low melting point and low hardness, which makes it cheap and lightweight.
- Wax Model & Tree Assembly
A wax model can be made by filling a mold with wax. A lot of these models are made by putting the wax in an aluminum alloy mold. Under normal conditions, these models can only make a stainless steel casting part. After taking out the wax models from their mold, workers need to check if they are the right size. If there is an error, they need to fix it or make another one. Next, they will stick the wax model onto a sprue. Before doing this, the model will be like a tree that has many branches. The tree will be first glued and then sprayed with sand. The sand is a type that is very hot, which makes it smooth.
Now it’s time to dry the wax model with sand using room-temperature water. This will not affect the dimensions of the internal wax pattern. The drying time will depend on how complex your product is, but it usually takes around 5 to 8 hours at first. After the first time, you spray and let it dry. Then paint and sand again. The second layer of sand is stronger because it has bigger particles. Then, spray more glue on the wax model and let it dry at a set temperature. After the second sand spraying, the go-ahead for the third one, too. After that, do four more.
- Sand Shell Making and Dewaxing
Before baking, you need to coat the shell with white latex evenly. This is used to stick the sand mold and seal wax models. It helps prepare for the baking process. After baking, it also improves how brittle the sand is so you can break through it and take out your part.
To make a model of wax, it is heated in an oven. Industrial wax melts at low temperatures, so the oven heats up to about 150°C. The melted wax will flow out the sprue gate. After being heated, all that is left is an empty sand shell. (You can reuse the wax many times, but it must be filtered again. If you do not filter the wax, it will affect the surface quality of stainless steel casting blanks and cause shrinkage.) To make the sand more solid, before pouring it into the steel water pot, we must bake it. We usually put it in an oven at a high temperature for a while (about 1000 degrees).
- Pouring
Pour molten stainless steel into a mold that is made from sand. Then liquid stainless steel water will fill the mold, including the middle part of the sprue gate. Be careful! The factory must make sure that there all of it has been melted before adding any other chemicals to it.
After solidification, it’s time to break the outermost sand shell with help of human power or mechanical tools to get them shape. The shape is also the final blank. Cut and separate it into pieces, then polish it to become a single stainless steel casting.
- Testing
This is a test. The stainless steel blank can be fixed with argon arc welding if you have any surface defects. For serious defects, you will need to clean and return the scrapped product to the furnace for the production of other stainless steel components. Sometimes these pieces will also still need to be further machined for final finished products. You can read more our other blog for still more clarity.