In this process, all metal alloys are available, we can customize investment castings according to your material specifications, and even material compositions is feasible for production. To ensure the best quality, we will do quality control in each investment casting process.
Below is the steps of a whole investment casting process in our foundry:
To achieve precision products, making tooling is the first step to start investment castings. Such tooling or pattern will be precision machined by CNC center. So tooling cost will be charged from our customers when sample order of a new product is placed. But it is just one-off paid, and we will not ask for this fee for further orders.
2.Wax Injection and Pattern Assembly
After a pair of casting patterns is completed, we will first make wax pattern, such wax pattern is obtained by injecting wax into the pattern. And you will see a model with the same dimensions of desired products. Again, we will repeat the injection job for more wax patterns. Then assemble these wax patterns onto the spruce. Finally hang these pattern assemblies in the room temperature for drying.
In this step, the pattern assembly will be dipped into a ceramic slurry, and coated with a refractory material. This process needs to be repeated several times until reaching a certain thickness and strength. Thus, the ceramic shell is built and then dried in an atmospherically-controlled environment.
Placing the shell in a steam autoclave and rapidly heated, so that the wax will be melt and run out through the gate and pouring up under high temperature. The ceramic shell molds must be fired to burn out the last traces of pattern material and to preheat the mold in preparation for casting, usually in the range of 1600-2000 degrees Fahrenheit. So investment casting also named as “lost wax casting”.
Casting is the key step in the whole investment casting process. After dewax, we will first melt the steel ingots into liquid status, and pour the liquid metal into the spruce, then cool it under room temperature for a while.
Break the ceramic shell, and cut the individual investment castings from the spruce. Finally remove the excess metal from casting body by grinding.
To improve the mechanical properties of casting blanks, heat treatment is usually done after finishing castings. Main heat treatment processes are: Normalizing, tempering, annealing, hardening and tempering, carburizing, etc. Please note, heat treatment is operated only when customers have such requirements, and extra cost will be counted.
8.Shot Blasting/Sand Blasting
To remove scales and achieve better surface finish, investment castings will be shot blasted or sand blasted by small steel balls. So all the foundries must be equipped with shot blasting machines.
9.Anti-rust Oil Painting and other Surface Treatments
To protect products from rusting, castings will be dipped into anti-rust water or oil. Of course, other surface treatments can also be performed in this step like paint spraying, galvanizing, etc.
Inspection is also a necessary step for quality investment castings. Our engineer will do dimensional inspection, 100% surface inspection, inner defects inspection and other inspection jobs according to requirements of products. Only ensure all the products are qualified, can we arrange delivery to our customers.
As all the products are exported to overseas market, so, normally we will pack investment castings with ploy bags, and then put them into standard wooden cases. Of course, all the package must be carried out on the basis of free from damage. We can also supply custom package service according to customers’ special requirements.