Steel is a general term for iron-carbon alloys with a carbon content between 0.02% and 2.11% by mass. The chemical composition of steel can vary greatly. Steel containing only carbon elements is called carbon steel (carbon steel) or ordinary steel; in actual production, steel often contains different alloying elements according to different uses, such as: manganese, Nickel, Vanadium, etc. The application and research of steel has a long history, but until the invention of the Bainian steelmaking method in the 19th century, the production of steel was a high-cost and low-efficiency work. Today, steel is one of the most used materials in the world due to its low price and reliable performance. It is an indispensable ingredient in the construction industry, manufacturing industry and people's daily life. It can be said that steel is the material basis of modern society.

Strictly speaking, steel is an iron-carbon alloy with a carbon content between 0.0218%-2.11 [2] %. We usually call it steel together with iron. In order to ensure its toughness and plasticity, the carbon content generally does not exceed 1.7%. In addition to iron and carbon, the main elements of steel include silicon, manganese, sulfur, and phosphorus. The other ingredients are there to differentiate the properties of the steel.

After the wax model is trimmed, wax trees need to be planted before further operations can be carried out.

To plant a wax tree is to weld the prepared wax mold to a wax rod in layers along the circumferential direction with a wax welding device in a certain order, so that a wax tree with a shape similar to a big tree is finally obtained. The wax tree is then poured into gypsum and other processes. The basic requirement for planting wax trees is that the wax molds should be arranged in an orderly manner. The key is that the wax molds should not be in contact with each other, so as to maintain a certain gap and weld the wax molds on the wax tree as much as possible. It is necessary to "plant" as many wax molds as possible on a wax tree to meet the needs of mass production.

A wax tree must be "planted" on a circular rubber base. The diameter of this rubber chassis is matched to the inner diameter of the stainless steel barrel. The diameter of the general rubber chassis is 3 inches, 3.5 inches and 4 inches. There is a protruding circular concave hole in the center of the chassis, and the diameter of the concave hole is equivalent to the diameter of the wax rod of the wax tree. The first step of "planting wax trees" is to dip the head of the wax stick in some melted wax liquid, and insert it into the concave hole of the chassis while it is still hot, so that the wax stick and the concave hole are firmly combined. The second step is to weld the wax model on the wax stick layer by layer, starting from the bottom of the wax stick (from bottom to top) or from the top of the wax stick (from top to bottom). If the technique of "planting trees" is relatively skilled, there is little difference between the two methods; however, there are generally more methods that start from the head of the wax stick (from top to bottom), because the biggest advantage of this method is that it can prevent The melted wax drips onto the welded wax pattern, which can avoid unnecessary rework caused by the dripping of wax.