The precision casting enterprise must conduct a comprehensive audit on the production management of castings, starting with the management of the mold (pressing). The material, accuracy, life and delivery time of the mold have an important impact on the quality of the casting. Precision casting companies generally belong to small batches and many specifications. For example, sewing machine castings include more than 200 accessories, which are more complex castings. Occupies a very important position in mold management. Therefore, our management of molds mainly includes:
1. The technical department is responsible for all the liaison of the mold design and mold production factory. Strengthen the selection, evaluation and confirmation of mold factories. As far as possible, choose professional mold manufacturers with advanced technology and equipment, and at the same time strengthen the management of mold testing work.
2. The quality control department is responsible for the inspection of new molds, wax molds, castings, calculation of shrinkage, and judgment of mold qualification.
3. The production department is responsible for the daily management of the mold, such as: mold registration, daily maintenance, storage, protection, evaluation, and handling of formalities for entering and leaving the warehouse.
Item is to strictly strengthen the quality control of raw materials. The quality of raw materials determines the quality of castings to a large extent. Selecting high-quality materials does not necessarily increase the production costs of castings.
The third is to pay close attention to quality control in the production process. The complexity of the precision casting process determines that each process in each production process must set up a "three inspections" system of full-time inspectors for the first inspection, patrol inspection, and completion inspection. First control the unqualified and transfer to the next process.
The fourth item is the control of the shell making process. Layer number parameters The surface layer is composed of the second layer, the second layer, the third layer, the fourth layer and the half layer; the coating type: 300/325 mesh zircon powder
The fifth item is dewaxing quality control. Many precision casting companies use high-pressure steam dewaxing methods. The process requires that the dewaxing steam pressure is between 0.6-0.75Mpa, and the pressure time to reach 0.6Mpa should be less than 14S. The entire shell dewaxing time is completed within 6-10min. Because the thermal expansion coefficient of the molding material is much larger than the thermal expansion coefficient of the mold shell, too long dewaxing time will cause the mold mold shell to swell. Therefore, after dewaxing, an inspector is required to check the quality of the mold shell and check whether the wax liquid in the mold shell Take off, whether the shell has cracks or bulging.
The sixth item is the quality control of shell roasting, metal smelting and pouring. Shell roasting is mainly to eliminate moisture and impurities in the shell, enhance the shell's strength and air permeability, and its temperature should not be too high or too low. Generally, companies use it in the range of 950-1050 ° C. One thing to pay attention to is that the operator should be careful when installing the shell and fork shell to prevent it from colliding, squeezing, dropping, and breaking.
The seventh item is post-process quality control. The post-processing steps mainly include dehulling, shot blasting, removing pouring feeders, repair welding, rough grinding, shaping, heat treatment, sand removal, mechanical polishing, pickling passivation, electrolytic polishing, and plastic spraying.
One is to ensure that the quality of the castings meets the delivery acceptance technical conditions, and all inspections must be performed in accordance with the casting advance drawing, investment precision casting technology standards, and the inspection contract submitted by both parties. Inspection mainly includes appearance quality inspection, internal quality inspection and other quality inspections.