Key points of quality management system operation of professional die enterprise

The technological process of casting production is mainly divided into four basic parts: casting metal preparation, mold preparation and casting, and casting treatment.
1, metal preparation, mainly metal smelting: metal as the main component (such as iron, aluminum or copper), adding other metal or non-metallic elements (chromium, manganese, vanadium, zinc, phosphorus, silicon, etc.) by heating melting into the specified composition of the molten metal (cast iron, cast steel and cast nonferrous metal).
Metal smelting – making metal molten liquid in temperature, chemical composition, and cleanliness conforms to the expected requirements. In the process of melting, various inspection tests for the purpose of controlling the quality, such as temperature testing, pre furnace chemical analysis, pre furnace treatment (desulfurization, vacuum degassing, refining, inoculation and modification), are required.
Common equipment are cupola, electric arc furnace, resistance furnace, induction furnace, etc.
2, mold preparation: different products, different casting methods have different mold preparation methods; sand mold, metal mold and so on. Commonly used sand casting, mold preparation content includes molding material preparation, core making, sand mixing (to control the composition and humidity of molding sand), and so on. (besides, there are casting designs for casting, riser design, casting system design, technology and model making). The accuracy of casting and the economic effect of the whole production process are mainly determined by this process. In modern production, the molding core has been mechanized or automated. The common equipment is: high and low pressure molding machine, sand throwing machine, core ejection machine, cold and hot core box machine.
In addition, there are also molten mold casting (dewaxing casting), etc.
3, metal casting is usually divided into two kinds of manual and mechanical casting. The production of cast iron is mainly made by hand casting, and the casting is made by lifting the iron water package from the crane to the lifting facility (whether the slag is sufficient before casting, the pouring temperature is suitable), and the non-ferrous metal casting is generally realized by the pressure casting machine. At this time, die casting process parameters, temperature, pressure and time, should be well controlled. All kinds of die casting machines are available in main facilities.
4, casting processing: mainly sand, sand cleaning, pouring riser cleaning, some of the castings have special requirements through heat treatment (such as castings annealing, nodular iron normalizing treatment, etc.), and antirust treatment. The equipment disposed includes sand knocking machine, shot blasting machine, various heat treatment furnace, etc.
In the process of production, the main factors to be concerned are: the temperature of melting, the composition of the molten liquid, and the casting temperature, and the control of the heat treatment process of the castings (heating temperature, heat preservation time, cooling rate).
The process of melting, casting and heat treatment should be controlled as a special process.
Cast iron castings should pay attention to the quality of the burden (coke, pig iron, scrap and nodular agent), especially in the scrap steel.
In addition, the production safety environment requirements: Casting environmental waterproofing, safety inspection of running iron ladle.
Relevant main technical standards:
GB/T 9439-1988 gray iron castings
GB/T 718-2005 cast iron for casting
GB/T 8729-1988 coke for casting
GB/T 11352-2009 cast carbon steel for general engineering
GB/T 1348-2009 spheroidal graphite cast iron
Evaluation method of surface roughness of GB/T 15056-1994 castings
Weight tolerance of GB/T 11351-1989 castings
Casting quality
In general, there are three aspects:
(1) internal quality: it includes casting material quality (chemical composition, metallographic structure, metallurgical defects, physical and mechanical properties).
Internal casting defects such as energy and some special properties).
(2) external quality: generally including casting surface quality (surface roughness, surface hard layer depth and hardness, etc.) and dimensions.
And weight accuracy (dimensional tolerances, geometric tolerances, weight tolerances) and casting defects.
(3) use quality: it includes cutting performance, welding performance and working life.
The cost of casting is an important part of product cost. To reduce the cost of products, we must reduce the cost of casting as far as possible. For a long time, not enough attention has been paid to the quality of castings. In particular, the internal quality and production cost of the castings, many manufacturers are used to the evaluation index of the quality of the castings. In fact, the rate of waste products can not represent the quality of the castings. It can only reflect the technical level and management level of the enterprise, so it can only reflect the technical level and management level of the enterprise. The neglect of internal quality and production cost makes castings less competitive in domestic and foreign markets.
Foundry production process is a complex process with various processes and related factors coming from many aspects. At present, there are some problems, such as low casting quality (especially internal quality), high production cost (low efficiency, high energy consumption) and serious environmental pollution. The reasons for these problems can be summarized as follows:
(“) the casting quality standard is not perfect and not clear. In China’s existing national standards, Ministry standards and technical guidance documents, the quality standards of casting are low and the quality requirements are low. Some of them are made in 60s and 70s. It is urgent to revise and draw close to international standards. Only by improving and strictly implementing the casting quality standards can the quality problems of foundry production in China be solved step by step.
The quality of various raw materials used in casting is low. Without high quality raw materials, it is difficult to produce high quality castings. For example, low sulfur and low phosphorus pig iron, high quality foundry coke is difficult to guarantee supply, casting sand has no unified production management organization, quality can not be guaranteed, other raw materials and auxiliary materials have similar conditions.
(!) the level of management is backward. In a long period of time