Precision casting enterprises should conduct a comprehensive review of the production management of castings. The project should start from the management of precision casting molds. The material, precision, life and delivery time of the molds have a very important impact on the quality of castings. Precision casting companies generally have small batches, specifications and varieties More. For example, sewing machine castings include more than 200 kinds of accessories, which are more complex. It plays a very important role in mold management. Therefore, our mold management mainly includes:
1. The technical department is responsible for mold design and all liaison work with mold manufacturers. Strengthen the selection, evaluation and confirmation of mold factories. Try to choose professional mold manufacturers with advanced technology and equipment, and strengthen the management of mold trial production.
2. The quality control department is responsible for the inspection of new molds, wax molds and castings, calculating their shrinkage rates, and judging whether the molds are qualified.
3. The production department is responsible for the daily management of molds, such as: mold registration, daily maintenance, storage, protection, evaluation and handling procedures for entering and leaving the warehouse.
The project is to strictly strengthen the quality control of raw materials. The quality of raw materials determines the quality of castings to a large extent, and the selection of high-quality materials does not necessarily increase the production cost of castings.
The third item is to pay close attention to the quality control in the production process. The complexity of the precision casting process determines that each process in the production process must have full-time inspectors, and implement the "3 inspection" system of first inspection, patrol inspection and completion inspection .First control the unqualified products, and transfer to the next process.
The fourth item is the control of the shell-making process. The surface layer parameters are the surface layer, 2 layers, 2 layers, 3 layers, and 4 half layers; coating type: 300\/325 mesh zircon powder, 200 mesh zircon powder
Item 5, dewaxing quality control. Many precision casting companies use high pressure steam dewaxing method. The process requires dewaxing steam pressure between 0.6-0.75Mpa, and the pressure time to reach 0.6Mpa should be less than 14S, and the entire shell dewaxing time It should be completed within 6-10min. Since the thermal expansion coefficient of the mold material is much larger than that of the shell, too long dewaxing time will cause the mold shell to crack. Remove the mesh, regardless of whether the shell has cracks or bulges.
Item 6, shell roasting, metal smelting and pouring quality control. The main purpose of shell roasting is to remove moisture and impurities in the shell and improve the strength and air permeability of the shell. One point to note is: the operator is loading the shell and Care should be taken when handling the fork housing to prevent bumping, crushing, dropping the housing and breaking.
Item 7, post-processing quality control. Post-processing mainly includes shelling, shot blasting, removal of pouring risers, repair welding, rough grinding, forming, heat treatment, sand cleaning, mechanical polishing, pickling passivation, electrolytic polishing, plastic spraying and other processes.
In order to ensure that the quality of the precision casting mold meets the technical conditions for factory acceptance, a comprehensive inspection must be carried out according to the casting drawings, investment casting technical standards and the inspection contract between the supplier and the buyer. The inspection mainly includes appearance quality inspection, internal quality inspection and other quality inspections.
