& nbsp; Lost foam casting is a new process with almost no margin and precise molding. This process does not require mold removal, no parting surface, and no sand core, so the casting has no flash, burrs, and draft angle, and reduces dimensional errors caused by core combinations. The surface roughness of the casting can reach Ra3.2 to 12.5μ m； The dimensional accuracy of castings can reach CT7 to 9; The maximum machining allowance is 1.5 to 2mm, which can greatly reduce the cost of mechanical processing. Compared with traditional sand casting methods, it can reduce the machining room by 40% to 50%.Edit Summarycatalogue[Hide ]1 Concept2. Characteristics of Lost Foam Casting Process2.1 1. High casting accuracy2.2 2. Flexible design2.3 3. No sand cores in traditional casting2.4 4. Clean production2.5 5. Reduce investment and production costs3. Development Status of Lost Foam Casting Technology at Home and AbroadIntroduction to the Advantages and Process Technology of Lost Foam Mold4.1 Purpose of the equipment4.2 II. Production Principle and Process Flow5 Main advantages of lost foam casting6 Lost Foam Casting Production Line6.1 Single machine or simple mold casting production line6.2 II. Domestic lost foam casting assembly line6.3 III. Imported Lost Foam Casting from Abroad7. Control of Lost Foam Casting Process  Lost Foam Casting - Concepts In 1958; H.F.shriyer of the United States invented the patented technology of manufacturing metal castings with expandable foam plastic patterns and obtained a patent (patent No. USP2830343). The initial pattern used was made from polystyrene (EPS) board processing, using clay sand molding to produce art castings. With this method, the foam plastic pattern does not need to be pulled out after molding, but after pouring liquid metal, the polystyrene molecule is cracked at high temperature to make space full of metal liquid, and the casting is formed after solidification. 1961; Grunzweig and Harrtmann companies in Germany purchased this patented technology for development and applied it in industry in 1962. The technology of producing castings using adhesive free dry sand was patented by H.Nellen from Germany and T.R. Smith from the United States in 1964. Due to the frequent collapse of dry sand without binders during the pouring process, A. Wittemoser in Germany in 1967 used magnetizable iron pellets instead of silica sand as the molding material, using a magnetic field as the "binder". This is called "magnetic mold casting". In 1971; Nagano from Japan invented the V method (vacuum casting method), which inspired today's lost foam casting to use vacuum pumping in many places to fix the molding sand. Before 1980, the use of adhesive free dry sand technology had to be approved by the Full Mold Process, Inc. of the United States. Since then, the patent has become invalid. Therefore, in the past 20 years, the lost foam casting technology has developed rapidly worldwide.Characteristics of Lost Foam Casting - Lost Foam Casting Process  1. High casting accuracy Lost foam casting is a new process with almost no margin and precise molding. This process does not require mold removal, no parting surface, and no sand core, so the casting has no flash, burrs, and draft angle, and reduces dimensional errors caused by core combinations. The surface roughness of the casting can reach Ra3.2 to 12.5μ m； The dimensional accuracy of castings can reach IT7 to 9; The maximum machining allowance is 1.5 to 2mm, which can greatly reduce the cost of mechanical processing. Compared with traditional sand casting methods, it can reduce the machining room by 40% to 50%.2. Flexible design It provides sufficient degrees of freedom for the structural design of castings. Highly complex castings can be produced by combination of foam plastic molds.3. No sand cores in traditional casting Therefore, there will be no occurrence of uneven casting wall thickness due to inaccurate sand core size or inaccurate lower core position in traditional sand mold casting.4. Clean production There is no chemical binder in molding sand. Foam plastic is harmless to the environment at low temperature. The recovery rate of used sand is more than 95%.5. Reduce investment and production costs Reduce the weight of the casting blank and reduce the machining allowance& nbsp; 　　  The lost foam casting process, like other casting processes, has its drawbacks and limitations. Not all castings are suitable for production using the lost foam process, and specific analysis is required. We mainly consider whether to adopt this process based on the following factors. The larger the batch size of castings, the more significant the economic benefits. The order of good or bad applicability of casting materials is roughly as follows: gray cast iron - non ferrous alloy - ordinary carbon steel - ductile iron - low-carbon steel and alloy steel; Make necessary preparations to avoid excessively long process experiments and debugging cycles. 3. The size of the casting mainly considers the range of use of the corresponding equipment (such as vibration table and sand box). 4. The more complex the casting structure, the more it can reflect the superiority and economic benefits of the lost foam casting process. For situations where there are narrow internal channels and interlayers in the structure, experiments need to be conducted in advance before using the lost foam casting process before it can be put into production.Lost Foam Casting - Development Status of Lost Foam Casting Technology at Home and Abroad In 1990; General Motors of the United States has established a new foundry in Saturu with an annual production capacity of 55000 tons and three fully automated lost foam casting production lines& nbsp; In 1991, Fiat Italia established; Built in Turin; The largest lost foam production workshop in Europe, with an annual output of 15000 tons& nbsp; In 1993, BMW Germany built a lost foam production line with an annual output of 200000 aluminum alloy cylinder heads of various specifications& nbsp; In 2001, General Motors' SMCO was built into the world's most advanced and largest lost foam casting plant& nbsp; After 20 years of exploration in China's lost foam casting industry, from hardware equipment to; The software technology has gradually matured, among which the Hongjinlong Foundry Machinery Factory in Kunming, Yunnan is relatively advanced in various aspects, and its products have been exported to; Malaysia and other neighboring countries. In addition, Tsinghua University; Higher education institutions such as Huazhong University of Science and Technology have also made valuable contributions to the development of the lost foam casting industry. Lost Foam Casting - Introduction to the Advantages and Process Technology of Lost Foam Casting  1、 Purpose of the equipment This set of equipment and process integrates the advantages of full mold and vacuum casting, suitable for various grades of steel, iron, aluminum, copper, and various materials and structures of large, medium, and small castings, with better results for complex castings& nbsp; 1. The structural shape is not limited by the casting process, providing a wide range of degrees of freedom for product design and manufacturing. The production cycle is short, the production efficiency is high, and there is no need for sand mixing, core removal, mold removal, box closing, and parting. It is easy to cast multiple or group castings in one box, achieving optimal design and avoiding casting defects and scrap caused by factors such as core removal, mold removal, and box closing; 2. The casting has high dimensional accuracy, accurate shape and size, good internal and external quality, and has the characteristics of precision castings, which can partially replace investment casting; Precision casting can reduce machining allowance by up to 60%, and the process yield can reach 95%& nbsp; 3. Low investment, fast start-up, fewer personnel, low cost, compact equipment, small footprint, easy to master process technology, and easy to achieve mechanical automation production.2、 Production principle and process flow This method follows the EPC process to first create a foam plastic model, apply a special coating, dry it, and place it in a special sand box. Fill it with dry sand, compact it with three-dimensional vibration, and cast it in a vacuum state. The model vaporizes and disappears, and the metal replaces the model to replicate the same casting as the foam plastic mold. After condensation, release the vacuum, and remove the casting from the loose sand for the next cycle& nbsp; 1. Making foam gasification molds (manually or mechanically)& nbsp; 2. Foam gasification, mold combination and drying& nbsp; 3. Brush and spray fire-resistant coating on the surface of the foam gasification mold and then dry it again (it must be completely dry)& nbsp; 4. Place the specially made sand box on a three-dimensional compaction table& nbsp; 5. Fill in low sand (dry sand), compact and scrape flat& nbsp; 6. Place the dried foam plastic gasification mold on the bottom sand, divide it into sand filling according to the process requirements, and automatically compact it for a certain time before scraping the box mouth& nbsp; 7. Cover the sand box mouth with plastic film, place the gating cup, and connect to the negative pressure system. After compaction, the steel liquid is poured, and the foam gasification mold disappears, with the metal liquid replacing its position& nbsp; 8. After the casting condenses, release the vacuum and flip the box, remove the casting and proceed to the next cycle.Lost Foam Casting - The main advantages of Lost Foam Casting 1. The casting has precise size and shape, good repeatability, and the characteristics of precision casting& nbsp; 2. The surface smoothness of the casting is high& nbsp; 3. The sand core and core making departments have been abolished, and casting defects and waste products caused by core making and core laying have been eradicated& nbsp; 4. Without proper box or mold removal, greatly simplifying the molding process and eliminating casting defects and scrap caused by mold removal and box closure& nbsp; 5. Adopting a dry sand mold without binder, moisture, and any additives, various casting defects and waste products caused by moisture, additives, and binders have been eliminated& nbsp; 6. The sand treatment system has been greatly simplified, and the molding sand can be fully reused, eliminating the molding sand preparation and waste sand treatment departments& nbsp; 7. Sand removal is extremely easy, greatly reducing the workload and labor intensity of sand removal& nbsp; 8. The casting has no flash or burr, reducing the cleaning and polishing workload by more than 50%& nbsp; 9. Reasonable shaped gates and risers can be set in ideal positions, without being constrained by traditional factors such as parting and mold taking, reducing internal defects in castings& nbsp; 10. Negative pressure pouring is more conducive to the filling and shrinkage of liquid metal, improving the structural density of castings& nbsp; 11. Combined pouring, with multiple pieces in one box, greatly improves the process yield and production efficiency of castings& nbsp; 12. Reduced machining allowance and reduced machining costs& nbsp; 13. It is easy to achieve mechanized automatic assembly line production, with high elasticity, and can produce castings of different alloys, shapes, and sizes on one production line& nbsp; 14. The draft angle can be cancelled& nbsp; 15. The service life of the metal mold used can reach over 100000 times, reducing the maintenance cost of the mold& nbsp; 16. Reduced dust, smoke, and noise pollution, greatly improved the working environment of foundry workers, and reduced labor costs; Dynamic intensity, industries dominated by male workers can become industries dominated by female workers& nbsp; 17. Simplified process operations, greatly reducing the requirement for workers' technical proficiency& nbsp; 18. The shape of the parts is not limited by traditional casting processes, freeing mechanical designers to freely design the most ideal casting shape based on the performance of the parts& nbsp; 19. Can reduce the weight of castings& nbsp; 20. Reduced production costs& nbsp; 21. Simplified factory design; Fixed assets investment can be reduced by 30-40%, and the floor area and building area can be  Reduce by 30-50%, and power consumption can be reduced by 10-20%& nbsp; 22. The lost foam casting process is widely used, not only for casting steel and cast iron, but also for casting copper, aluminum, etc& nbsp; 23. The lost foam casting process is not only suitable for castings with simple geometric shapes, but also for castings with multiple edges, multiple cores, and complex geometric shapes that are difficult to master in ordinary casting& nbsp; 24. The lost foam casting process can achieve pouring under microseismic conditions, promote the formation of metallographic structures with special requirements, and is conducive to improving the internal quality of castings& nbsp; 25. Combined casting in dry sand makes it easy to remove sand and synchronize the temperature, so waste heat can be used for heat treatment; Reason. Especially the water edge treatment of high manganese steel castings and the solid solution treatment of heat-resistant steel castings have very ideal results, which can save a lot of energy and shorten the processing cycle& nbsp; 26. By utilizing the lost foam casting process, castings of any size can be completed based on their melting capacity. Lost Foam Casting - Lost Foam Casting Production Line  1、 Single machine or simple mold casting production line Generally, 1-2 sets of three-dimensional vibration tables (used for molding), several to more than 10 special sandboxes, sandboxes hoisting or simple conveyor lines with rollers (rails) are set in the casting workshop. Dry sand is generally Free cooling or equipped with simple molding sand cooling devices, plus a set of vacuum pumping system and sand dust removal screening equipment. Flexible investment, with costs ranging from 80000 to 150000 yuan, and a production scale typically ranging from 500 to 5000 tons. This production model is relatively in line with China's national conditions, with low spending and fast start-up, and is highly welcomed by the majority of small and medium-sized enterprises in China, with rapid development. This type of factory accounts for over 90% of the lost foam casting factories in China.2、 Domestic lost foam casting assembly line A domestically designed production line using mechanical, hydraulic, pneumatic, and electronic control methods, with a number of sand boxes ranging from 10 to 50; All are equipped with sand cooling system equipment; The production scale ranges from 2000 to 30000 tons per year, with investments ranging from 500000 to 4 million. There are approximately 30 such production plants. The characteristic is a complete system, complete functions, continuous operation, suitable for large-scale production.3、 Imported Lost Foam Casting from Abroad Among these factories introduced from abroad, the investment is only about 10 million yuan, while the investment is mostly (accumulated) about 80 million yuan, usually between 40 to 50 million yuan. Lost Foam Casting - Control of Lost Foam Casting Process The lost foam casting process includes riser system design, pouring temperature control, pouring operation control, negative pressure control, etc& nbsp; The gating system plays a very important role in the lost foam casting process and is a key factor in the success or failure of casting production. Due to the wide variety and different shapes of castings, each casting's specific production process has its own characteristics and varies greatly. These factors directly affect the accuracy of the gating system design results& nbsp; The design of the gating system is somewhat different from traditional sand casting. In the design of the gating system, the particularity of this process should be taken into account, as the cross-sectional dimensions of each part of the gating system are related to the size of the casting, the combination of model clusters, and the number of pieces per box& nbsp; The combination method of model clusters can basically reflect the characteristics of castings and the feeding form of castings. Due to the presence of model clusters, the behavior of molten metal after pouring is significantly different from that of sand casting. During the pouring process, the gasification of the model requires absorption of heat, so the pouring temperature of lost foam casting should be slightly higher than that of sand casting& nbsp; When designing the cross-sectional dimensions of each part of the pouring system, consideration should be given to the resistance generated by the presence of the model during the pouring of molten metal in lost foam casting. The minimum resistance flow area should be slightly larger than that of sand casting& nbsp; Negative pressure is a necessary measure for black alloy lost foam casting. The negative pressure operation is an important guarantee measure for increasing the strength and stiffness of the molding sand, and it is also the main measure to eliminate the gasification products of the model. The magnitude and holding time of negative pressure are related to the casting material, model cluster structure, and coating& nbsp; The most taboo in the pouring operation of lost foam casting is intermittent pouring, which can easily cause cold shut defects in the casting, that is, the temperature of the molten metal poured first decreases, leading to a cold shut between the molten metal poured later. In addition, the lost foam casting pouring system often adopts a closed pouring system to maintain the smoothness of pouring. The form of the pouring cup is closely related to whether the pouring operation is smooth. During pouring, the liquid level in the pouring cup should be kept stable, and the dynamic pressure during pouring should be stable.