Lost wax casting is one of the oldest known metal casting techniques, having been practiced for approximately 6,000 years. Lost wax casting is simply the process of creating a wax model or pattern to be used as the original template for metal parts. Today's lost wax casting is used in a wide variety of applications, including but not limited to jewelry making Jewelry making, dentistry, and artwork.
Lost wax casting method, in the beginning, was a purely manual process, the time and effort required is incalculable. But now, with the development of science and technology, more digital technology has also been applied to the lost wax casting method, creating more convenience for people.
What is the lost wax casting method?
As mentioned above, the lost wax casting method involves making a template out of wax first to create the metal part. In fact, wax molds can be used directly to make metal castings, and this method is known as the direct method. Alternatively, the wax mold can be used to make a replica of the wax mold, which is known as the indirect method. What follows is a detailed description of the entire process of the lost wax casting method.
- Making a wax model: The first step in the lost wax casting method is to make a wax model. Generally speaking, there is already a drawing of the design before making the wax model. However, whether the final model is the same as the one shown on the drawing depends on the skill of the wax sculptor who makes the wax template. Another element to consider is the volume of the casting equipment you will use. The volume of the mold you make must be less than the maximum volume of the casting equipment.
- Processing wax models: Since a wax model is melted after only one use, it is very troublesome and time-consuming to recreate it. Therefore it is better to make a master model out of the wax model first. The master model is the wax mold made in the first step of casting the metal parts The wax mold is used to cast the metal parts. Afterwards, heated rubber is wrapped around the parts to create a durable rubber mold. Rubber molds are reusable, and this point is its outstanding advantage.
- Make the wax mold again: pour the melted wax into the rubber mold made above and you have a perfect replica of the mold.
- Making the Wax Tree: The molds made in the previous step should not be taken directly and used to make metal molds. Instead, a sprue is added to the mold. Since the mold looks like a tree, it is also called a wax tree. The purpose of this is to prepare the mold for the subsequent wax flow and the filling of the metal.
- Encase the mold in a special material: here you need to encase the metal on the outside of a material to make a template for metal casting. Here you have two options, a silica solution and a liquid plaster that is configured according to the proportions. Then all you have to do is wait for the material to solidify and take shape.
- Melting the wax molds: take out the molds that have just been solidified and molded, and place the molds one by one into a hot environment. Wait for the wax to completely melt and flow out, and you will have a poured model.
- Metal Pouring: The mold obtained in the previous step is put back into a high temperature environment to be heated (this is done in order to prevent the temperature difference between the mold and the molten metal from being too large and causing the mold to break). Subsequently,melting the metal and pour the already melted and finished metal into the mold.
- Removing the metal parts: After the metal has completely solidified, you can remove the metal parts. You can knock off the external material with a small hammer. After removing the metal part you can put it in water and quench it to remove any plaster or silica that has adhered to the metal part. Afterwards, the sprue is removed (you can save it for the next casting).
- Subsequent processing: At this point in time, the metal castings may more or less have certain imperfections left on them. Therefore, subsequent processing is required, including but not limited to engraving, grinding or sandblasting.
History of the Lost Wax Casting Method
With regard to the history of the lost wax casting method, it was mentioned above that its history can be traced back as long as 6 000 years. So, you can even say that its history is even as long as the history of human civilization. Moreover, the lost wax casting method is still widely distributed, including countries such as Vietnam and Israel, which have the tradition of using the lost wax casting method.
In addition, it can be said that the field of application regarding the lost wax casting method is quite wide. In addition to being used to make some metal parts in engineering manufacturing, it can also be used to make some fine jewelry. In addition, in the field of dentistry, the lost wax casting method can also be used to make overlays or inlays.
What will the incorporation of digital technology bring to the lost wax casting method?
As mentioned above, with the continuous progress and development of society, digital technology has been applied to the lost wax casting method, and has brought a lot of convenience to people. First of all, the real modeling, designers can use CAD software to carry out the design of the mold. Designers can change the design at any time, and the operation is very convenient. Secondly, the emergence of 3D printing technology, so that the precision of mold production has risen to another level. This not only saves time, but also greatly reduces the errors that may occur in the process of making templates.
