Casting is an ancient manufacturing method that can be traced back to 6000 years ago in our country. With the development of industrial technology, the development of casting technology is also very rapid, especially in the late 19th century and the first half of the 20th century, there have been many new casting methods, such as low-pressure casting, ceramic casting, continuous casting, etc., in the 20th century Half leaf is perfected and practical. Due to the increasing requirements for casting quality, casting accuracy, casting cost and casting automation, casting technology is developing in the direction of precision, large-scale, high quality, automation and cleanliness.
The casting technology, special casting technology, casting automation and casting molding simulation technology have developed rapidly. The main casting processes include: metal smelting, model manufacturing, casting solidification and mold release cleaning. The main materials used for casting are cast steel, cast iron, and cast nonferrous alloys (copper, aluminum, zinc, lead, etc.). The casting method commonly used is sand casting, followed by special casting methods, such as: metal casting, investment casting, gypsum casting... and so on. The sand casting can be divided into clay sand, organic binder sand, resin self-hardening sand, lost foam, etc., as shown below: The principles of casting method selection: 1. Preferential use of sand casting According to statistics, in my country or internationally, 60 to 70% of all castings are produced with sand molds, and about 70% of them are produced with clay sand molds. The main reason is that sand casting has lower cost, simpler production process and shorter production cycle than other casting methods. Therefore, castings such as engine cylinder blocks, cylinder heads, crankshafts, etc. of automobiles are all produced using the clay wet sand process. When the wet type can not meet the requirements, consider using clay sand surface dry sand type, dry sand type or other sand type. The casting weight of the clay wet sand casting can be from a few kilograms up to several tens of kilograms, while the castings produced by the clay dry mould can weigh several tens of tons. Generally speaking, for medium and large castings, cast iron parts can be produced with resin self-hardening sand molds, and steel castings can be produced with water glass sand molds. Castings with accurate dimensions and smooth surfaces can be obtained, but the cost is higher. Of course, the casting precision, surface finish, material density, metallographic structure, mechanical properties, etc. produced by sand casting are often poor, so when these performance requirements of castings are higher, other casting methods should be used, such as investment casting (loss Wax) casting, die casting, low pressure casting, etc. 2.
The casting method should be compatible with the production batch. For example, sand casting, mass production factories should create conditions to adopt technologically advanced modeling and core making methods. The production line of the old-style shock or shock molding machine is not high enough, the labor intensity of the workers is large, the noise is large, and it is not suitable for the requirements of mass production, and it should be gradually reformed. For small castings, you can use the horizontal or vertical type of boxless high-pressure molding machine production line, real molding production efficiency is high, and the floor space is also small; for middle parts, various boxed high-pressure molding machine production lines, gas The molding line is punched to meet the requirements of a fast and high-precision molding production line. The core making method can be selected: cold core box, hot core box, shell core and other efficient core making methods. For medium-sized large-scale castings, resin self-hardening sand molding and core making can be considered. Single-piece, small-batch production of heavy castings, manual molding is still an important method, manual molding can adapt to various complex requirements is relatively flexible, does not require a lot of process equipment. Water glass sand type, VRH method water glass sand type, organic ester water glass self-hardening sand type, clay dry type, resin self-hardening sand type and cement sand type, etc.; for single-piece heavy castings, the pit molding method is low in cost and put into production fast. It is more appropriate to use multi-box molding and split-box molding for mass-produced or long-term stereotyped products. Although molds, sand boxes, etc. start to invest heavily, they can be compensated for saving molding time and improving product quality. Low-pressure casting, die casting, centrifugal casting and other casting methods are only suitable for mass production because of the high cost of equipment and molds. 3. The molding method should be suitable for the factory conditions. For example, the production of large machine tool beds and other castings is generally used. The core molding method is generally used, and the core is formed in the pit without making patterns and sand boxes; while the other factories use the sand box molding method to make appearance. Different enterprises’ production conditions (including equipment, venues, staff quality, etc.), production habits, and accumulated experience are different. Based on these conditions, what products are suitable and what are not (or cannot) products should be considered. 4. It is necessary to take into account the accuracy requirements and costs of castings. The accuracy of castings obtained by various casting methods is different, the initial investment and productivity are also inconsistent, and the final economic benefits are also different. Therefore, to achieve more, faster, better, and more economical, all aspects should be taken into consideration. A preliminary cost estimate should be made of the casting method selected to determine the casting method with high economic benefits and that can guarantee the casting requirements. The characteristics and application scope of the casting method are shown in the following table: Casting Method Casting Material Casting Weight Surface Finishing Casting Complexity Production Cost Applicability Scope Process Features Sand Mold Casting Various Materials tens of grams ~ Very Different Simple and Low Most Common Casting Methods Manual Molding: Single Mechanical modeling of large castings with complex shapes that are difficult to use for molding parts, small batches and difficult to use molding machines: suitable for mass production of small and medium castings. Manual: flexible and easy, but low efficiency, high labor intensity, low dimensional accuracy and low surface quality Machinery: The dimensional accuracy and surface quality are high, but the cost of https://www.bronzecast.net/ investing tens of grams to 20 kilograms of large metal mold casting nonferrous alloys and good complex casting metal molds is relatively high.
Non-ferrous alloy castings produced in small batches or large batches are also used to produce steel castings. Casting precision, high surface quality, dense structure, good mechanical properties and high productivity. Investment casting cast steel and non-ferrous alloy a few grams to a few kilograms are very good. Mass production of any complexity is cheaper than complete machining. It is a small complex precision casting of various batches of cast steel and high melting bronze cast factory point alloys, especially suitable for casting art, Precision mechanical parts have high dimensional accuracy and smooth surface, but they have many processes and large labor intensity. Ceramic casting steel and cast iron are a few kilograms to hundreds of kilograms. They are very complex and expensive. Molds and precision castings have high dimensional accuracy and smooth surfaces, but the productivity is low. Casting aluminum, magnesium, zinc alloys are tens of grams to tens of kilograms, very complex and complex. High single piece to small batch low-pressure casting nonferrous alloys are tens of grams to tens of kilograms. Very complex (available sand core) metal mold production cost is high Batches, preferably large batches of large and medium-sized nonferrous alloy castings, can produce thin-walled castings with a dense structure, high process yield, simple equipment, and can use a variety of casting molds, but low production efficiency. Differential pressure casting aluminum and magnesium A few grams to dozens of kilograms of alloy is complex (available sand core). The high-performance and complex-shaped nonferrous alloy castings have controllable pressure, good casting molding, dense organization and good mechanical properties, but low production efficiency. Low pressure casting aluminum and magnesium alloys a few grams ～Several dozens of kilograms of complex (available sand core) metal molds are very expensive to produce. Various non-ferrous alloy small and medium-sized castings, thin-walled castings, pressure-resistant castings, high-precision castings, smooth surface, dense structure, high productivity low cost. However, the cost of die-casting machines and molds is high. Centrifugal casting gray iron and ductile iron are tens of kilograms to several tons. Generally, cylindrical castings are low. Rotary body castings from small batches to large batches, and pipe castings of various diameters have high dimensional accuracy. , Smooth surface, dense structure, high productivity Continuous casting steel, large colored poor long continuous castings Low fixed cross section long castings, such as steel ingots, steel pipes and other dense structures, good mechanical properties, high productivity Grams to a few tons are better, more complex, lower, and more complex. Various alloy castings with different batch sizes have higher dimensional accuracy, greater freedom of casting design, and simple processes, but the combustion of the pattern affects the environment.
The casting technology, special casting technology, casting automation and casting molding simulation technology have developed rapidly. The main casting processes include: metal smelting, model manufacturing, casting solidification and mold release cleaning. The main materials used for casting are cast steel, cast iron, and cast nonferrous alloys (copper, aluminum, zinc, lead, etc.). The casting method commonly used is sand casting, followed by special casting methods, such as: metal casting, investment casting, gypsum casting... and so on. The sand casting can be divided into clay sand, organic binder sand, resin self-hardening sand, lost foam, etc., as shown below: The principles of casting method selection: 1. Preferential use of sand casting According to statistics, in my country or internationally, 60 to 70% of all castings are produced with sand molds, and about 70% of them are produced with clay sand molds. The main reason is that sand casting has lower cost, simpler production process and shorter production cycle than other casting methods. Therefore, castings such as engine cylinder blocks, cylinder heads, crankshafts, etc. of automobiles are all produced using the clay wet sand process. When the wet type can not meet the requirements, consider using clay sand surface dry sand type, dry sand type or other sand type. The casting weight of the clay wet sand casting can be from a few kilograms up to several tens of kilograms, while the castings produced by the clay dry mould can weigh several tens of tons. Generally speaking, for medium and large castings, cast iron parts can be produced with resin self-hardening sand molds, and steel castings can be produced with water glass sand molds. Castings with accurate dimensions and smooth surfaces can be obtained, but the cost is higher. Of course, the casting precision, surface finish, material density, metallographic structure, mechanical properties, etc. produced by sand casting are often poor, so when these performance requirements of castings are higher, other casting methods should be used, such as investment casting (loss Wax) casting, die casting, low pressure casting, etc. 2.
The casting method should be compatible with the production batch. For example, sand casting, mass production factories should create conditions to adopt technologically advanced modeling and core making methods. The production line of the old-style shock or shock molding machine is not high enough, the labor intensity of the workers is large, the noise is large, and it is not suitable for the requirements of mass production, and it should be gradually reformed. For small castings, you can use the horizontal or vertical type of boxless high-pressure molding machine production line, real molding production efficiency is high, and the floor space is also small; for middle parts, various boxed high-pressure molding machine production lines, gas The molding line is punched to meet the requirements of a fast and high-precision molding production line. The core making method can be selected: cold core box, hot core box, shell core and other efficient core making methods. For medium-sized large-scale castings, resin self-hardening sand molding and core making can be considered. Single-piece, small-batch production of heavy castings, manual molding is still an important method, manual molding can adapt to various complex requirements is relatively flexible, does not require a lot of process equipment. Water glass sand type, VRH method water glass sand type, organic ester water glass self-hardening sand type, clay dry type, resin self-hardening sand type and cement sand type, etc.; for single-piece heavy castings, the pit molding method is low in cost and put into production fast. It is more appropriate to use multi-box molding and split-box molding for mass-produced or long-term stereotyped products. Although molds, sand boxes, etc. start to invest heavily, they can be compensated for saving molding time and improving product quality. Low-pressure casting, die casting, centrifugal casting and other casting methods are only suitable for mass production because of the high cost of equipment and molds. 3. The molding method should be suitable for the factory conditions. For example, the production of large machine tool beds and other castings is generally used. The core molding method is generally used, and the core is formed in the pit without making patterns and sand boxes; while the other factories use the sand box molding method to make appearance. Different enterprises’ production conditions (including equipment, venues, staff quality, etc.), production habits, and accumulated experience are different. Based on these conditions, what products are suitable and what are not (or cannot) products should be considered. 4. It is necessary to take into account the accuracy requirements and costs of castings. The accuracy of castings obtained by various casting methods is different, the initial investment and productivity are also inconsistent, and the final economic benefits are also different. Therefore, to achieve more, faster, better, and more economical, all aspects should be taken into consideration. A preliminary cost estimate should be made of the casting method selected to determine the casting method with high economic benefits and that can guarantee the casting requirements. The characteristics and application scope of the casting method are shown in the following table: Casting Method Casting Material Casting Weight Surface Finishing Casting Complexity Production Cost Applicability Scope Process Features Sand Mold Casting Various Materials tens of grams ~ Very Different Simple and Low Most Common Casting Methods Manual Molding: Single Mechanical modeling of large castings with complex shapes that are difficult to use for molding parts, small batches and difficult to use molding machines: suitable for mass production of small and medium castings. Manual: flexible and easy, but low efficiency, high labor intensity, low dimensional accuracy and low surface quality Machinery: The dimensional accuracy and surface quality are high, but the cost of https://www.bronzecast.net/ investing tens of grams to 20 kilograms of large metal mold casting nonferrous alloys and good complex casting metal molds is relatively high.
Non-ferrous alloy castings produced in small batches or large batches are also used to produce steel castings. Casting precision, high surface quality, dense structure, good mechanical properties and high productivity. Investment casting cast steel and non-ferrous alloy a few grams to a few kilograms are very good. Mass production of any complexity is cheaper than complete machining. It is a small complex precision casting of various batches of cast steel and high melting bronze cast factory point alloys, especially suitable for casting art, Precision mechanical parts have high dimensional accuracy and smooth surface, but they have many processes and large labor intensity. Ceramic casting steel and cast iron are a few kilograms to hundreds of kilograms. They are very complex and expensive. Molds and precision castings have high dimensional accuracy and smooth surfaces, but the productivity is low. Casting aluminum, magnesium, zinc alloys are tens of grams to tens of kilograms, very complex and complex. High single piece to small batch low-pressure casting nonferrous alloys are tens of grams to tens of kilograms. Very complex (available sand core) metal mold production cost is high Batches, preferably large batches of large and medium-sized nonferrous alloy castings, can produce thin-walled castings with a dense structure, high process yield, simple equipment, and can use a variety of casting molds, but low production efficiency. Differential pressure casting aluminum and magnesium A few grams to dozens of kilograms of alloy is complex (available sand core). The high-performance and complex-shaped nonferrous alloy castings have controllable pressure, good casting molding, dense organization and good mechanical properties, but low production efficiency. Low pressure casting aluminum and magnesium alloys a few grams ～Several dozens of kilograms of complex (available sand core) metal molds are very expensive to produce. Various non-ferrous alloy small and medium-sized castings, thin-walled castings, pressure-resistant castings, high-precision castings, smooth surface, dense structure, high productivity low cost. However, the cost of die-casting machines and molds is high. Centrifugal casting gray iron and ductile iron are tens of kilograms to several tons. Generally, cylindrical castings are low. Rotary body castings from small batches to large batches, and pipe castings of various diameters have high dimensional accuracy. , Smooth surface, dense structure, high productivity Continuous casting steel, large colored poor long continuous castings Low fixed cross section long castings, such as steel ingots, steel pipes and other dense structures, good mechanical properties, high productivity Grams to a few tons are better, more complex, lower, and more complex. Various alloy castings with different batch sizes have higher dimensional accuracy, greater freedom of casting design, and simple processes, but the combustion of the pattern affects the environment.
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