Introduction of precision casting
Precision casting is also named as lost wax casting, refers to the general term for the process of obtaining precision-sized casting.
Thus, precision casting is a type of casting craft that can cast the grey iron casting parts or ductile iron casting products with a smooth better surface than sand casting. At the same time, the precision cast machine parts can be installed directly on the machinery product like forklift or vehicle without or with little processing.
In total, investment casting is an advanced process, which includes investment casting, ceramic casting, metal casting, pressure casting, and lost foam casting.
Basic Concept of lost wax casting
Lost wax casting is a common casting, whose process is as below:
- To select the suitable investment materials such as paraffin for investment mold;
- Repeat the process of dipping refractory paint and refractory sand on the investment mold to harden the mold shell and dry it;
- To dissolve the internal investment mold to obtain the cavity;
- Roast the shell to obtain sufficient strength, and burn off the residual investment material;
- Pouring the metal materials needed;
- Wait for solidification and cooling, then sand removal after shelling, to obtain high-precision finished products.
- To do heat treatment, cold processing and surface treatment according to the requirement of iron casting products.
The production process of Precision casting:
Generally, the casting production process includes wax pressing, shell making, pouring, post-processing and inspection.
- Wax pressing includes (pressure wax, wax repair, tree formation), and use wax pressing machine for making wax mold
- Wax repair — modify wax mold
- Group tree — group the wax model
- Shell making includes (hanging sand, hanging pulp, air-drying)
- Pouring includes (roasting, the chemical analysis also called playing spectrum, pouring, shock shell, cutting gate, grinding gate)
- Post-processing includes (sand blasting, shot blasting, correction, pickling)
- The inspection includes (wax inspection, preliminary inspection, intermediate inspection, finished product inspection)