High Volume Manufacturing Parts test of your design is a must as it allows you to test your die casting product(as lighting die casting parts) and refine your ideas. That makes it an important aspect of the product development process. While it can be expensive and time-consuming, you have the option to outsource it to a reputable cnc machining service. Thus, you can focus on other areas of your project and ensure the speedy and accurate creation of an aesthetic or functional model for your design.
During Precision Machining, your research and development team can identify and validate promising concepts based on the design samples. A prototype allows them to test the design’s core features with users to have a clearer idea of how the concept can meet the market demand. It also lets them make the necessary adjustments to the design before it goes into final production.
The CNC Machining service eliminates the need to purchase your die casting molding material and manufacturing devices. This way, you can save time and money while ensuring that your final product can be realized faster and cost-effectively, with better ROI.
Avoid product failure
The service provider can ensure accurate and precise manufacturing of your CNC Machining samples based on your exact design. This way, product designers can identify any flaws and make corrections or improvements. Moreover, it ensures a more ergonomic way to identify and evaluate product hazards.
The CNC Machining samples shows the exact function and aesthetics of your product.CNC Machining and Surface Treatment services will ensure speedy results so you can test and retest quickly and find ways to fine-tune your ideas.
Access to more technologies
A reputable rapid cnc prototype machining service offers a range of technologies and solutions to create functional or aesthetic products. These include Metal 3D printing, vacuum casting, injection molding, and CNC machining.
Make sound decisions
Established providers of cnc machining services in China can review your project for free. It’s a great chance to learn how they can help you, especially if you’re unsure which die casting methods are best for your design.
Getting your product from the drawing to a tangible version is a crucial aspect of design. Without it, you have no way to test and validate your design before it’s finalized for mass production. Die casting is one of the ways you can bring your designs to life. It involves die casting – molds manufacturing – cnc machining, which delivers high precision, fast, and durable prototypes of parts from a billet or block of your chosen material that is cut with a series of drill bits and tools.
Die casting allows you to volume make your model with almost all kinds of materials that can withstand heat and stress. Some of the most popular materials used are aluminum, zinc, and special alloy like magneium and copper.
Die Casting Machining methods
Die casting uses the cavity of the mold to apply high pressure to the molten metal. Molds are usually machined from stronger alloys, a process somewhat similar to injection molding.
Your Die Casting project
Die casting is used typically for volume building high-quality prototypes for functional testing. However, it’s also practical for crafting custom casts or molds to build prototypes for other production processes, such as injection molding. In this case, the CNC machining prototyping process also qualifies as rapid tooling.
Die Casting Tolerances
CNC machines can be very accurate, but running the mill on the highest accuracy can be time-intensive and costly. That’s why tolerances are used, and these are measurements indicating the level of precision required for the prototype you’re making. In short, they represent the degree of variation permitted in the measured value or final dimensions of the part. Reputable providers of CNC prototyping and edm wire cutting services control their tolerances to DIN-2678-1 Medium for Fine for metals.
If you’re designing volume die casting of a part or product, choose a manufacturing process that can build it using the same material. In metal die casting, you can consider the process of cold chamber die casting process, which can build parts from different metal materials one layer at a time. Cold chamber die casting services is a injection chamber and the injection punch are not immersed in the molten metal, but a quantitative amount of molten metal is poured into the injection chamber and then injected. ,. This way, it can create highly complex shapes when other manufacturing methods can’t.
However, you need to know the best metals that can be used for your display die casting or other project. Choosing the correct metal will ensure optimum results and an effective die casting process that will improve your chances of success.
Which metals can be used in die casting?
Which Metal Should You Choose For Die Casting?Reputable manufacturers offer a range of materials, such as aluminum, zinc, copper, and magneium. These metals come with various properties, making them ideal for a range of applications. For instance, if you require volume production of automotive parts, pipes, or valves; aluminum and aluminum alloy can be a good option for offering outstanding corrosion resistance.
Metals to avoid in die casting
Any metal may be used in die casting if it can be supplied as an appropriate metal. However, materials that burn instead of melt at high temperatures should be avoided as they cannot be melted safely or sintered. Metals to avoid in die casting:
Benefits of Die Casting with High Volume
High Volume Thin Wall Die Casting and cnc machining is a versatile metal manufacturing technology that lets you build functional metal rapid prototypes and parts with complex shapes or geometries. It’s used extensively in the medical, automotive, and aerospace industries for fulfilling part consolidation and weight-saving application requirements. Creating prototypes and low-volume end-use parts out of Thin Wall Die Casting metals are typically detailed but not necessarily structurally sound.
Aluminum alloy die-casting products are mainly used in electronics, automobiles, motors, home appliances and some communication industries. Some high-quality aluminum alloy thin wall die casting products with high performance, high precision and high toughness are also used in large aircraft, ships and other industries with relatively high requirements. . The main use is still on the parts of some instruments.
Casting aluminum alloy ingot production process: electrolytic aluminum liquid, waste aluminum ingot, scrap – batching – smelting tool preheating – slag removal in ladle – furnace loading – mixed smelting – furnace temperature control – slag removal and degassing – casting tool preheating ——Open the furnace hole to release molten aluminum – pouring – slag – cooling into indium – inspection – coding – packing – finished casting of aluminum alloy ingots.
Smelting operation: As described above, the pouring process is basically the same as that of ordinary casting, and the specific operations are related to the smelting of aluminum alloys and the casting of aluminum ingots for remelting.
It is mentioned in the die casting theory of aluminum die castings that continuous casting of horizontal ingot molds is the most commonly used casting method in aluminum electrolysis plants. Aluminium ingots for remelting of aluminium and aluminium alloys. A special volume die casting machine is used to realize this casting.
The horizontal continuous ingot casting method is a casting method with a high degree of mechanization of the block iron mold ingot casting method. The die casting mold technology is relatively simple. Because the aluminum alloy ingots for remelting are produced, the defects on the surface of the ingots and the requirements for the internal crystalline structure are relatively not strict. There are still requirements for pinhole grades inside the ingot. For the specific requirements of die casting ingots, please refer to the standard “Casting Aluminum Alloy Ingots”
Die Casting Process Control
The requirements for the process of horizontal continuous casting are mainly pouring temperature, pouring speed and water cooling control(The Theory Of Aluminum Die Casting).
Pouring temperature The casting temperature of aluminum and aluminum alloy ingots for re-cultivation is different due to the different alloy varieties. In general, the pouring temperature of common aluminum and deformed aluminum alloys is in the range of 30-80 degrees above the crystallization temperature of the alloy. Cast aluminum alloys are in the range of 30 – 50 degrees above the crystallization temperature.
Pouring speed Horizontal ingot mold continuous casting is a fixed casting machine. Different types of casting machines have different casting speeds. The casting speed is adjustable, and the casting speed is expressed by the travel speed of the mold. But to be more intuitive, foundries generally test casting speed by casting several ingots per minute. It should be emphasized that the casting speed should not be adjusted too fast, otherwise, it may cause the die casting machine to vibrate greatly, and the ingot will have serious ripples and surface oxidation.
Cooling control The cooling method of the horizontal ingot mold continuous casting machine is divided into two types: one is the forced water-cooling type immersed at the bottom of the casting mold, which mainly controls the inlet water temperature to be below 40 degrees and the return water temperature to be below 60 degrees. The other is the natural cooling method of the ingot, but in order to ensure the normal operation of the casting machine, it is necessary to reduce the temperature of the casting mold, and spray cooling with water before or after the demoulding of the ingot, so as to reduce the temperature of the casting mold, that is, to avoid die casting mold cost.The equipment failure that may occur in the high temperature operation of the casting machine is also conducive to the demolding of the ingot and the stability of the process conditions. This cooling method generally requires the water spray temperature to be below 40 degrees.
What Is Die Casting?Die Casting and it is a precision casting method that obtains the same casting as the mold by injecting molten metal into a steel mold that is precisely machined to perfectly match the required casting shape. In addition to the advantages of almost no need for finishing as the dimensions are accurate, it has excellent mechanical properties and is capable of mass production.Die casting is also called pressure die casting. It is a precision casting method in which molten metal is injected into a steel mold that is precisely machined to perfectly match the required casting shape to obtain a casting identical to that of the mold. The product is called die-casting parts.
In addition to the advantage that there is little need for finishing because the dimensions are accurate, it has excellent mechanical properties and can be mass-produced. The metal used is an alloy such as zinc, aluminum, tin, copper, and magnesium, and it is cooled and solidified by injecting it by air pressure, water pressure, or hydraulic pressure using a die-casting machine.
There are many automobile parts as products, including parts for electrical equipment, optical equipment, vehicles, weaving equipment, construction equipment, and measuring instruments.
The Definition And Terminology Of Die Casting
Die casting is defined as “a casting method that mass-produces castings with excellent casting surfaces with high precision by pouring molten metal into a precision mold and products resulting from it”. In Japanese, the word “die casting” is also used, but American die casting is adopted. In the UK, mold casting is called gravity die casting, low pressure casting is called low pressure die casting, and die casting is called pressure die casting.
The Characteristics Of Die Casting
The main advantages and disadvantages of die casting are as follows.
Products with complex shapes can be mass-produced in one process.
Because it is high-speed and high-pressure filling, there is no molten metal vortex and the dimensional accuracy of the casting state is good.
Because it is a high-speed and high-pressure filling, the hot water flow is good, a thin product can be made, and the casting surface is beautiful.
The productivity per hour is good because it is fast charging and rapid cooling and solidification.
Mechanical properties are improved by the formation of a seven-layer by rapid cooling.
Coping with pores caused by the inflow of air or gas.
Solution treatment or welding cannot be performed due to the inflow of air or gas.
Since the mold is expensive, economical mass production cannot be secured.
Die Casting Machine
Because the sleeve and flanger are not in the molten metal and are not heated, it is called a gold chamber.On the other hand, a machine called a hot chamber is used for die casting of zinc or magnesium and is not used for aluminum alloy. Cold chamber die casting machines in Japan have a minimum clamping force of 0.5MN and a maximum of 40MN. The injection force is 1/10 to 10/20 of the clamp force.
Die Casting Cycle
One cycle of aluminum alloy die casting by cold chamber machine will be described.
a) Close the two molds by matching the movable mold to the fixed mold by the machine’s mold clamping operation. With a ladle, molten aluminum alloy is poured into a sleeve called a cold chamber.
b) The plunger operates and presses the molten metal into the mold cavity at high speed and high pressure. The mold is water cooled to prevent overheating.
c) When the molten metal solidifies, open the mold and return the flanger and the moving core to their original state.
The size of the machine used depends on the size of the die-casting product. One cycle of die casting takes several seconds for small size and several minutes for large size. In recent die casting production, some factories are aiming to automate their operations and unmanned them.
Casting pressure, which is a typical casting condition item of aluminum die casting, is in the range of 10 to 200 MPa, and the gate speed is in the range of 2 to 100 m/s. The casting conditions of die casting are quite different from those of gravity casting.
Features are as follows
Cast with high pressure
Cast at high speed. Therefore, the filling time into the mold is very short
In the mold, the filled molten metal is rapidly cooled and solidified.
Die Casting Manufacturing Process
Die casting work performed in most factories is supported by automatic hot water supply device, plunger lubrication device, automatic spraying device, product dispensing device, etc., and is being mechanized and systemized. Fully automatic operation and unmanned operation are also being realized. The trimming device mainly relies on the knitting press operation, but sand blasting or shot blasting are also used in combination. In post-processing, machining and surface treatment are performed. For the surface treatment, buffing, chemical conversion, painting, anodizing, plating, and the like can be selected.
Dimensional Tolerance Of Die Casting
It goes without saying that the dimensional accuracy required for a product is after final processing, and errors in material and processing are added.
Dimensional tolerance = casting tolerance + mold tolerance + shrinkage vs. calculation tolerance + tolerance for casting operation
Calculation formula for maximum possible dimensional tolerance – ε=±0.75×10-³×L。(mm)
Calculation formula for precise dimension tolerance – ε=±(1.15×10-³×L。+0.1) (mm)
Calculation formula for general dimensional tolerance – ε=±(2.15×10-³×L。+0.2) (mm)
In this case, L. is the length of the mold cavity at room temperature, and ε is the dimensional difference of the die casting. The factor that fluctuates the casting tolerance is the mold temperature difference.As a standard for dimensional tolerance, there is JIS B 0409 die casting normal tolerance, and the normal tolerance of length and the maximum value of degradation angle are determined.Japan Die Casting Association standardized the details again and indicated length tolerance, angle tolerance, flatness tolerance, and eccentricity tolerance.
The Mechanical Properties Of Die Casting
The mechanical properties of die casting show the measured values of the simple shape individual molten metal injection test pieces and the measured values of the test pieces cut from mass-produced products. In general, the former is larger than the latter. ASTM test pieces are distributed as individual molten metal injection test pieces.
The strength of die casting cannot be guaranteed as a substitute characteristic. Apply a load corresponding to the actual and practical load to the die casting to destroy it, and obtain a numerical value that can be statistically guaranteed to withstand the load, for example, the lower limit of 3σ.
Die Casting Defects And Countermeasures
The extent to which defects are allowed depends on the required quality of the product, so the limit should be clearly defined when trading.
(G) Japan Die Casting Association has suggested casting surface standards and foam standards. There is also a new defect name called Fracture Layer. It is explained that the solidified layer generated in the injection sleeve of die casting is an abnormal tissue that is broken by the flanger and flows into the molten metal into the cavity. The strength of the interface between the fractured layer and the normal tissue is significantly lower than the strength of the normal tissue as it is inserted at less than 9kgf/mm². This is the cause of extremely lowering the strength of the die casting. According to the degree of demand for the strength of die casting, the development of a method for preventing the occurrence of a fracture layer is in progress. Methods to increase the heat retention of the molten metal in the sleeve just before injection, such as the ceramic sleeve method and the powder lubrication method, are being sought.
New Die Casting Method
Die casting has been quantitatively expanded by using high productivity and good flow of hot water for thin products as sales points. However, the high-speed charging that realizes it, on the one hand, cannot avoid air bubbles due to mixing.
may be the cause Several new die casting methods have been developed in response to product design requirements such as filling, airtightness, and strength leveling as castings, and heat treatment or welding.
(1) Vacuum Method
The history of vacuum method is quite old. Methods currently industrially known include the GF method, the mass vent method, the shutter-off pin method, the RSV method, the superback method, the MFT method, and the VACURAL method. The vacuum method widely used in Japan is the GF method.
(2) PF Method
Also called non-porous die casting. The principle is to eliminate air bubbles by purging the mold cavity and sleeve with oxygen, mixing oxygen with the molten metal in the spray state by high-speed injection, and fixing oxygen with Al₂O₃. Die casting made by PF method can be solution heat treated and artificial aging heat treated. Sometimes welding.
(3) Local Pressure Method
After filling the mold cavity with the molten metal, a local pressure higher than the casting pressure is applied to the molten metal or the reaction solid in the cavity by pressing a pressure pin by a predetermined stroke. There is an effect of filling the voids of the decrease in the cavity volume caused by such pressurization. It is effective as a countermeasure against air bubbles in the thick part isolated in the part away from the gate.
(4) Hot Chamber Method
The hot chamber machine method is named because the injection mechanism is immersed in the molten metal. Since the steel injection mechanism part is easily eroded by the molten aluminum alloy, a hot chamber machine is usually not used for aluminum alloy die casting. However, if this method can be applied with high productivity, high level of automation, and stability of molten metal quality, new demand development can be expected for aluminum alloy die casting. In 1987, the Small and Medium Business Corporation tested a hot chamber die casting machine with a clamping force of 2.5MN. Ceramic materials such as silicon nitride are used for parts in contact with molten aluminum alloy. As a result of the operation test, improvement in quality, slimming, productivity improvement, and energy saving can be expected.
(5) Collapsible Core Method
One of the disadvantages of die casting is the restriction on the undercut shape. One of the solutions is to use a metal neutralizer setting. Another method, which is a collapsible reactor, uses salt or silica sand as an aggregate.
The Development Of Die Casting
The global aluminum die-casting market is expected to show continuous growth in accordance with the trend toward lighter weight of parts used in the automotive and aerospace fields.
Grand View Research’s ‘Global Aluminum Die Casting Market’ report that contains such content forecasts that it will grow at a CAGR of 5.1% from 2021 to 2028, reaching $35.64 billion in 2028.
Aluminum die casting is a process of injecting molten aluminum by applying pressure to a mold, and is divided into pressure die casting and other processes depending on the production process.
According to the report, high pressure die casting manufacturer (HPDC) in the production process sector accounted for the largest revenue share in 2020 and this trend is expected to continue through 2028. This is explained by the high preference for HPDC among casting manufacturers due to the high efficiency of the process.
It also points out that increasing demand for aluminum die casting or zinc die casting products is intensifying competition in the market, leading market players to gain a competitive edge through strategic initiatives such as mergers and acquisitions (M&A) and increased production capacity and to gain a competitive edge in losses from the impact of COVID-19. expected to recover.
The metal materials used in die casting are mainly aluminum alloys, magnesium alloys, zinc alloys and copper alloys. Since aluminum alloy die castings are widely used in the automotive industry, they account for a high proportion of die castings. According to the statistics of China Foundry Association, the proportion of aluminum alloy die castings in die castings is about 85%.
Market overview of die casting industry
(1) Overview of the international market
In recent years, with the development of the global economy, the demand for precision die castings in many fields such as automobiles, 3C products, communication infrastructure equipment, household appliances, and medical equipment has steadily increased.
At present, the market maturity of die casting parts in developed countries is relatively high. With the improvement of die casting equipment and process technology, more and more ferrous metal castings are replaced by non-ferrous metal die castings such as aluminum alloy and magnesium alloy. The production and consumption of global die castings are mainly concentrated in the United States, China, Italy, Germany, Mexico, Japan and other countries.
For developed countries, due to their leading advantages in equipment and technology, china automotive die-casting industry is generally dominated by high-quality and high-value-added die-casting such as automobiles, communications, and aviation.
The number of die-casting enterprises in developed countries is small, but a single enterprise has a large scale and a high degree of specialization, and has strong advantages in capital, technology, and customer resources.
According to the “State of the Industry Report and Research & Development” released by NADCA in October 2013, in 2012, my country was the world’s largest producer of die castings, accounting for 34% of the world’s total output.
(2) Overview of the domestic market
With the gradual accumulation of downstream manufacturing industries in China, my country’s die-casting industry has also developed by leaps and bounds with the improvement of China’s overall industrialization level, and has gradually developed into the world’s largest die-casting country. From the perspective of the output of die-casting parts, with the continuous and rapid development of my country’s automobile, communication infrastructure, 3C products, equipment manufacturing, home appliances, electromechanical instruments, light industry and other industries, as well as the transfer of foreign die-casting industries to China, die casting china industry has entered a new normal of steady growth.
As more and more high-end manufacturing industries transfer their production capacity to China, China’s die-casting industry is also continuing to upgrade its structure in the process of growth, and the proportion of precision die-casting parts is gradually increasing. As of the end of 2013, the proportion of China’s die-casting products used in the automotive industry has exceeded 70%, which is basically the same as that of developed countries.
As the most important category of products in the die-casting industry, the demand for auto parts, especially aluminum alloy die-casting parts for automobiles, will largely affect the overall development prospects of the die-casting industry. From the perspective of the structure of the whole car, in addition to the large number of precision die-casting parts used in the automobile engine, gearbox, transmission system, steering system, and electronic control system, aluminum alloy die-casting parts have also been used for large components such as the body frame.
Market overview of automotive die casting industry
As the most important application field of die-casting products, a large number of precision die casting parts are used in automobile engines, gearboxes, transmission systems, steering systems, and electronic control systems. The demand for auto parts will greatly affect the overall development of the die-casting industry. prospect.
As people pay more and more attention to automobile energy saving and environmental protection, the automobile industry has shown a trend of replacing steel and iron with aluminum in the past three decades, and this trend is still continuing. At present, the global aluminum alloy die casting market for automobiles is showing a rapid development trend as a whole.
In addition, in addition to aluminum alloy die castings, zinc alloy, magnesium alloy and copper alloy die castings are also used in automobiles.
The demand for aluminum, zinc and other metal die castings in the automotive industry will continue to grow in the future, which is mainly affected by the following factors:
China’s auto industry will maintain a relatively fast development speed
Since the reform and opening up, with the rapid growth of my country’s economy, the automobile die casting industry has also achieved rapid development. In 1980, my country’s automobile production was 222,300 units, and by 2016, it increased to 28,120,000 units, an increase of 125.49 times. In recent years, affected by the international and domestic economic situation, the growth rate of my country’s automobile production has declined, but due to the high base, the annual new automobile production is still quite large.
In 2016, my country’s private car ownership was 146 million, with 36 cars per 100 households, far below the level of developed countries. Therefore, china auto industry still has a lot of room for development in the future.
The trend of lightweight automobiles
The so-called lightweight of the car is to reduce the curb weight of the car as much as possible on the premise of ensuring the strength and safety performance of the car, thereby improving the power of the car, reducing fuel consumption and reducing exhaust pollution. For the lightweight of the whole vehicle, different components can contribute to different degrees. The lightweight of the body, interior and exterior trim, and power system is of great significance for reducing energy consumption during vehicle driving. Aluminum alloy materials are lightweight, recyclable and easy to form. Theoretically, an aluminum car can reduce the weight by 30%-40% compared with a steel car, among which the aluminum engine can reduce the weight by 30%, the aluminum radiator is 20%-40% lighter than the copper one, and the all-aluminum body is 40% lighter than the steel one. % or more, the weight of automobile aluminum wheels can be reduced by 30%. Therefore, aluminum alloy material is one of the most ideal materials for automobile lightweight.
Since 2011, due to the consideration of reducing greenhouse gas emissions and reducing the dependence on fossil energy, the indicators of automobile fuel consumption have been continuously improved. As one of the key technologies for vehicle energy saving, light weight has a significant energy saving effect. A 10% weight reduction for gasoline passenger vehicles can reduce fuel consumption by 3.3%, and a 15% weight reduction can reduce fuel consumption by 5%; for diesel passenger vehicles, fuel consumption can be reduced by 3.9% and 5.9% respectively.
Lightweight also has a good energy saving effect on electric vehicles (including plug-in hybrids). Weight reduction of 10% and 15% can achieve 6.3% and 9.5% of power consumption, respectively. The researchers also conducted related experiments on trucks of different energy categories, and also showed good energy-saving effects.
Reducing the weight of the car can reduce the engine load, improve the driving performance of the car, effectively reduce the braking distance, and make the steering and cornering process more flexible, thus making the car more stable, and the aluminum alloy structure can absorb and disperse more energy when it is impacted. , thus more comfortable and safe. Affected by this, the penetration rate of aluminum used in various major components of automobiles will increase significantly in the next decade. According to Ducker Worldwide, the penetration rate of aluminum hoods will increase from 48% in 2015 to 85% in 2025, and the penetration rate of aluminum doors will increase from 6% in 2015 to 46% in 2025. Specifically reflected in the average aluminum consumption per bicycle, the average aluminum consumption per vehicle in North America was 54kg in 1980, and increased to 154kg in 2010. It is expected that the average aluminum consumption per vehicle will reach nearly 325kg by 2025.
(3) The development of new energy vehicles will further promote the demand for metal die castings
One of the main problems of current new energy vehicles is the short cruising range, and lightweight design has become the main measure for reducing weight and consumption of new energy vehicles. Taking Tesla (TESLA) Model S as an example, its total weight is 2,108kg, and the weight of the battery alone exceeds 500kg. In addition, the drive motor increases the weight of the whole vehicle; while the total weight of the engine of a traditional car is generally 80-160kg. The mileage of a 70L gasoline car can reach 700-900Km, while the cruising range of an electric vehicle with a 500kg battery is only about 400Km. Therefore, increasing the proportion of automotive aluminum alloy die castings is the main measure to reduce the weight of new energy vehicles.
With the release and implementation of my country’s automobile energy saving and emission reduction policies, my country’s new energy vehicles have shown a rapid development trend in recent years. In 2016, the cumulative production of new energy vehicles was 517,000, an increase of 49.99% over 2015. Among them, the output of pure electric passenger vehicles increased most significantly, up 73.10% compared with 2015; the production of pure electric commercial vehicles increased by 50.20% compared with 2015; the output of plug-in hybrid electric passenger vehicles increased by 29.9% compared with 2015. From January to June 2017, the cumulative production of new energy vehicles was 212,000, an increase of 19.77% over the same period of the previous year. Among them, the output of pure electric passenger vehicles increased most significantly, up 30.60% over the same period of the previous year.
New energy vehicles have stricter requirements on body weight than traditional energy vehicles, so more lightweight aluminum alloy die-casting parts are used. For example, 95% of the Tesla (TESLA) Model S series models use aluminum alloy materials. The sustained and rapid growth of new energy vehicles will form a strong impetus for the development of the automotive aluminum alloy die casting industry.
What are the technical requirements for precision casting
Let’s take sand casting as an example. Factories that mass-produce precision casting should create conditions to adopt technologically advanced modeling and core-making methods. The old-fashioned shock or shock molding machine production line is not high enough in productivity, labor-intensive, and noisy, and cannot meet the requirements of mass production, so it should be gradually transformed. For small castings, a boxless high-pressure molding machine production line with horizontal or vertical parting can be used, which has high production efficiency and small footprint for solid molding; for medium parts, various boxed high-pressure molding machine production lines, gas Punching molding line to meet the requirements of fast and high-precision molding production line, core making methods can be selected: cold core box, hot core box, shell core and other efficient core making methods, and medium-volume large castings can be considered to use resin no-bake sand Shape and core.
For heavy-duty castings produced in small batches, die casting mold is still an important method. Manual molding can adapt to various complex requirements and is more flexible, and does not require a lot of process equipment. It can be applied to water glass sand mold, VRH water glass sand mold, organic ester water glass self-hardening sand mold, clay dry mold, resin self-hardening sand mold and cement sand mold, etc. For heavy castings produced in a single piece, the pit molding method is low in cost and can be put into production. quick. For mass-produced or long-term shaped products, it is more appropriate to use multi-box molding and split-box molding methods. Although the initial investment in molds and sand boxes is high, it can be compensated from the reduction of molding man-hours and the improvement of product quality.
Casting methods such as low pressure casting, die casting and centrifugal casting are only suitable for mass production due to expensive equipment and molds.
Conditional method should be suitable
For example, in the production of castings such as the bed of a large machine tool, the core forming method is generally used, instead of making the pattern and the sand box, the core is assembled in the pit; while other factories use the sand box molding method to make the pattern. Different enterprises have different production conditions (including equipment, site, staff quality, etc.), production habits, and accumulated experience. According to these conditions, it is necessary to consider what products are suitable and what products are not suitable (or cannot).
Accuracy Requirements and Costs
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, in order to achieve more, faster, better and more economical, all aspects should be taken into account. A preliminary cost estimate should be made for the casting method chosen to determine the most cost-effective casting method that will meet the casting requirements.
Experts said that in order to fundamentally improve the level of casting technology, the following four points must be achieved:
First, develop simulation technology to improve prediction accuracy, strengthen process control, and improve yield. The problem of regularity is not well grasped, which affects the yield in mass production.
Second, the combination of production, education and research. Independent innovation of enterprises In addition to the enhancement of innovation awareness and the improvement of research and development capabilities, it is also necessary to pay attention to and strengthen the combination of “production, learning and research” with precision casting enterprises as the main body.
Third, attach importance to material research and development. Materials are the foundation of industry, and there is still a lot of work to be done. In the field of aerospace, the research and smelting technology of alloy materials, especially some new materials such as superalloys, still needs to be improved, and there is still a big gap with foreign countries.
Fourth, pay attention to the improvement of equipment technology. The process is mainly a problem of equipment. Many key equipment, such as some directional solidification equipment, mainly rely on imports. Therefore, the research and development of precision casting equipment and die casting company are still the focus.
The method of casting liquid metal into a casting cavity suitable for the shape of the part, and after the casting is cooled and solidified, is called casting. Castings obtained by casting are called castings.
Casting structure design: ensure its working performance and mechanical performance requirements, consider the requirements of casting process and alloy casting performance on the casting structure, and whether the casting structure design is reasonable or not has a great impact on the quality, productivity and cost of the casting.
Design main issues and design requirements
The design of the box should first consider the arrangement of the parts in the box and the relationship with the external parts of the box. For example, the shape and size of the box should be determined according to the requirements of the two tops of the lathe. In addition, the following issues should be considered:
⑴, to meet the strength and stiffness requirements. For box parts that are under great stress, meeting the strength is an important issue; but for most boxes, the main indicator for evaluating performance is stiffness, because the stiffness of the box not only affects the normal operation of the transmission parts, but also affects the components. Working precision. Quick and easy automatic selection of castings is included.
⑵, heat dissipation performance and thermal deformation problems. The friction and heat of the parts in the box will change the viscosity of the lubricating oil and affect its lubricating performance; the temperature rise will cause thermal deformation of the box, especially the thermal deformation and thermal stress with uneven temperature distribution, which have a great impact on the accuracy and strength of the box. influences.
The structure design is reasonable. Such as the arrangement of the fulcrum, the arrangement of the ribs, the position of the opening and the design of the connection structure, etc., are all conducive to improving the strength and rigidity of the box.
⑷, good craftsmanship. Including blank manufacturing, machining and heat treatment, assembly adjustment, installation and fixation, hoisting and transportation, maintenance and repair and other aspects of craftsmanship.
Casting generally does not apply pressure, does not require high strength of equipment and molds, has small restrictions on product size, and has low internal stress in products. Therefore, the production investment is less, and large-scale parts with excellent performance can be obtained, but the production cycle is long, and mechanical processing must be carried out after molding. On the basis of traditional casting, methods such as pouring, invest casting, pressure casting, spin casting and centrifugal casting are derived.
①Perfusion. The difference between this method and casting is that the product is released from the mold after casting, while the mold is an integral part of the product itself during pouring.
② Embedded casting. Various non-plastic parts are placed in the mold cavity and solidified with the injected liquid material to encapsulate them.
③Pressure casting. Applying a certain pressure to the material during casting is conducive to injecting the viscous material into the die casting mold and shortening the filling time. It is mainly used for epoxy resin casting.
④ Spin casting. After the material is injected into the mold, the mold rotates around a single axis or multiple axes at a low speed, and the material is distributed on the inner wall of the mold cavity by gravity, and shaped by heating and curing. For the manufacture of spherical, tubular and other hollow products.
⑤ Centrifugal casting. A quantitative liquid material is injected into a mold that rotates at a high speed around a single axis and can be heated, and the material is distributed on the inner wall of the mold cavity by centrifugal force, and is solidified into a tubular or hollow cylindrical product by physical or chemical action (see Figure [centrifugation]. casting]). Monolithic cast nylon parts can also be formed by centrifugal casting.
What are the characteristics and main applications of aluminum alloy casting?
Aluminum alloy has low density, but relatively high strength, close to or surpassing high-quality steel, good plasticity, can be processed into various profiles, has excellent electrical conductivity, thermal conductivity and corrosion resistance, widely used in industry, and its usage is second only to steel . The following editor will introduce to you the characteristics and main applications of aluminum alloy casting.
Features of aluminum alloy casting:
1) Good fluidity to fill the narrow part of the slot.
2) It has a lower melting point than ordinary metals, but it can meet the requirements of most situations.
3) Good thermal conductivity, the heat of molten aluminum can be quickly transferred to the casting mold, and the casting cycle is short.
4) Hydrogen and other harmful gases in the melt can be effectively controlled by treatment.
5) When aluminum alloy is cast, there is no tendency of hot brittle cracking and tearing.
6) Good chemical stability and strong corrosion resistance.
7) It is not easy to produce surface defects, the surface of the casting has good surface finish and gloss, and it is easy to carry out surface treatment
8) Casting aluminum alloy machining has good processing performance. It can be used for casting production by pressing mold, hard mold, green sand and dry sand mold, investment plaster mold, vacuum casting, low pressure and high pressure casting, squeeze casting, semi-solid casting. Casting, centrifugal casting and other methods are used to form various castings with different uses, different specifications and different properties. Cast aluminum alloys are widely used in cars, such as engine cylinder heads, intake manifolds, pistons, wheel hubs, steering booster housings, etc.
What are the main applications of aluminum alloy casting?
Casting aluminum alloy is an die casting alloy that fills the mold with molten metal and obtains blanks of various shapes. It has the advantages of low density, high specific strength, good corrosion resistance and casting manufacturability, and is less restricted by the structural design of parts. Divided into Al-Si and Al-Si-Mg-Cu-based medium-strength alloys; Al-Cu-based high-strength alloys; Al-Mg-based corrosion-resistant alloys; Al-Re-based heat-strength alloys. Most require heat treatment to strengthen alloys, eliminate internal stress in castings, stabilize microstructure and part size. Used to manufacture beams, gas turbine blades, pump bodies, pylons, hubs, air intake lip and engine casings, etc. It is also used in the manufacture of automobile cylinder heads, gearboxes and pistons, instrumentation housings and supercharger pump parts.
Casting aluminum alloy has good casting properties, and can be made into parts with complex shapes; it does not require huge additional equipment; it has the advantages of saving metal, reducing costs, and reducing man-hours, and is widely used in the aviation industry and civil industry. Used to manufacture beams, gas turbine blades, pump bodies, pylons, hubs, air intake lip and engine casings, etc. It is also used in the manufacture of automobile cylinder heads, gearboxes and pistons, instrumentation housings and supercharger pump parts.