Investment Casting Process

Investment casting includes making mold - wax injection - wax repair - wax tree - shell making - dewaxing - pouring - shot blasting and other process steps.

1、Making mold

Senjia Heavy Industry has a professional design team, which can provide pertinent suggestions and reasonable solutions for customers' product design.The quality of abrasive design not only affects the use of the mold, but also can improve the production output and reduce the production cost of products. There is a big difference in the quantity of one or more products produced at a time.

2、Wax injection 

Wax injection is to heat the wax at a certain temperature, remove water, clean and stop it into paste, and then die cast into the wax shooting machine with a certain pressure.There is a certain geometry of the mold, the formation of the needed wax models.

Before wax injection, the mold must be checked, the temperature of the wax cylinder and the pressure of the wax injection machine must be adjusted, and the temperature control switch of the wax shooting machine must be opened 10-15 minutes in advance for preheating.

3、Wax Repair

(1) Clean wax mold line and flapping edge, ensure wax mold smooth, clear font, uniform thickness can not be deformed.

(2) Before wax injection, a wax mold must be submitted to the inspector to confirm that it meets the specifications before production.

(3) Special parts cannot be repaired with blades, so they must be repaired with other tools.

(4) Do not touch wax mold, put neatly, handle gently, do not squeeze.

4、Wax Tree

Group tree belongs to the process of wax injection (mold making) workshop, that is, the qualified wax type (after the quality inspection process) group to the mold head, to make a complete pouring system -- commonly known as tree string. Tools are usually made of copper plates about 1-2 mm thick. Many control points need to be paid attention to when assembling trees, such as the spacing of the workpiece, the inclination of the workpiece, the technique and strength of assembling trees, etc., because the assembling process may affect the following process, such as dipping, dewaxing, replenishing and cutting off. So the tree process requires a certain amount of experience.

5、Shell Making

Dip pulp is shell mold production process, and shell mold is made of binder (silicic acid glue), refractory materials and sand materials (sand, powder materials, the company is currently using zirconium powder (sand), powder (sand) and Malay sand) with slurry, slurry sticking sand, drying and hardening, wax and roasting processes.

The slurry made of binder and refractory powder is the foundation of shell mold structure, slurry surface layer and reinforcement layer (back layer) two kinds, surface layer slurry and metal contact, it should form smooth, dense, solid smooth shell mold surface, and does not interact with the metal liquid, in order to ensure the surface quality of the casting. The backlayer slurry is thickened to strengthen the shell mold, so that it has good comprehensive performance.

Only paste can not form a shell mould, still need to do reinforcement material adhering sand, adhering sand can adsorption in the slurry solvent, to stop the flow, prevent loss of slurry large, adhering sand slurry when also can prevent dry hardening layer is large shrinkage and the formation of a wide crack, additional adhering sand can cause rough shape on the back shell, is advantageous to the upper and lower two layers of shell mold, Sand also helps to improve the permeability of the shell.

6、Dewaxing

Dewaxing refers to the process of putting the wax shell into the dewaxing machine and melting the wax at high temperature to get the intact wax shell.

Every day after dewaxing, to clean the boiler and dewaxing furnace, and thoroughly discharge water, gas once.

7、Pouring

Casting is the process of casting the shell mold after a certain period of time and meet the requirements of the product. Because the shell mold needs to be sintered at high temperature, and the external size of the product is strict, the selected refractory must have enough room temperature and high temperature strength; Good thermal deformation resistance, good air permeability, good thermal stability, thermal expansion coefficient should be small, should not occur in the metal liquid chemical reaction. The good and bad of shell molding will be shown here.

Will use to a variety of alloy elements in the melt, conditioning, deoxidization, slag, multiple link would have factors affecting product quality, in actual operation, there are many need to pay attention to the details of the processing of liquid steel is very important work, a direct impact on product quality by the quality of molten steel, so for the processing of steel will be strict requirements in order to do better.