The investment casting process is precise and complex. First, a wax pattern that is exactly the same as the shape of the casting needs to be carefully prepared. The wax pattern material is usually made of low-melting-point wax material, which is formed by precision mold pressing or advanced technologies such as 3D printing. The wax pattern is not only accurate in size, but also has extremely low surface roughness, which can perfectly present the complex details required for the casting. Subsequently, several layers of refractory material are carefully applied to the surface of the wax pattern to form a solid shell. Each layer needs to be dried and hardened after application to ensure that the shell has sufficient strength and stability. After the shell is made, it is heated to above the melting point of the wax pattern, so that the wax pattern melts and flows out, leaving a hollow cavity in the shell with the same shape as the wax pattern. Next, the high-temperature molten liquid metal is poured into the shell cavity at a precise temperature and speed. After the liquid metal cools and solidifies, the shell is removed to obtain a high-precision investment casting. The entire process is extremely strict in controlling factors such as temperature, time, and materials. Each link requires a high degree of professional technology and rich experience to ensure that the quality of the final casting reaches an excellent level.
1. Specific application of investment castings in general machinery
Pump parts
In pump products, the impeller is the core component, and its performance directly determines the working efficiency and delivery capacity of the pump. Investment casting can produce impellers with extremely complex shapes to meet the stringent requirements for fluid dynamics under different working conditions. For example, for pumps used to transport corrosive media in the chemical industry, the impeller usually needs to have a special shape and structure to improve corrosion resistance and fluid delivery efficiency. Investment casting can accurately control the blade shape, thickness, and flow channel size of the impeller to ensure that the impeller can work efficiently and stably when rotating at high speed. In addition, as a key component for accommodating and guiding fluids, the smoothness and dimensional accuracy of the internal flow channel of the pump body have a significant impact on the performance of the pump. Investment castings can achieve high-precision molding of the internal flow channel of the pump body, reduce the resistance of the fluid in the flow channel, and thus improve the overall efficiency of the pump.
Valve parts
Valves play a key role in controlling fluid flow, pressure and flow direction in general mechanical systems. Valve parts produced by investment casting, such as valve bodies and valve cores, have high-precision dimensions and smooth surfaces. The internal flow channel shape of the valve body is complex, and the dimensional accuracy and surface quality requirements are extremely high. Investment casting can accurately replicate the flow channel shape in the design drawing to ensure that the fluid can pass smoothly when the valve is opened and closed, reducing pressure loss. As the key moving part of the valve, the matching accuracy between the valve core and the valve seat directly affects the sealing performance of the valve. The valve core manufactured by investment casting has high dimensional accuracy and low surface roughness. It can achieve a close fit with the valve seat, effectively prevent fluid leakage, and ensure the reliable operation of the valve.
Compressor parts
The core components of the compressor, such as crankshafts, connecting rods, pistons, etc., have extremely high requirements for strength, accuracy and wear resistance. Investment casting has significant advantages in manufacturing these parts. Take the crankshaft as an example. It has a complex shape and is subjected to huge alternating loads. Investment casting can accurately control the dimensions of each part of the crankshaft, ensure its dynamic balance performance at high-speed rotation, and reduce vibration and noise. At the same time, by reasonably selecting casting materials and processes, the strength and wear resistance of the crankshaft can be improved and its service life can be extended. Connecting rods and pistons also need to have high-precision dimensions and good comprehensive performance. Investment casting can produce connecting rods and pistons that meet these requirements, ensuring that the compressor has stable performance and reliable quality while operating efficiently.
Reducer parts
Gears, housings and other parts in reducers are the key to achieving power transmission and speed conversion. Gears manufactured by investment casting have high tooth shape accuracy and good surface quality. Accurate tooth shape can ensure the stability and transmission efficiency of gears during meshing, reduce noise and wear. At the same time, by controlling the cooling rate and organizational morphology during the casting process, the strength and toughness of the gears can be improved to meet the use requirements under different working conditions. As a component that supports and protects the internal gear transmission mechanism, the reducer housing needs to have sufficient strength and good dimensional accuracy. Investment casting can produce boxes with complex structures and precise dimensions, ensuring the installation accuracy and running stability of internal gears.
Other general machinery parts
In addition to the above typical parts, investment castings are also widely used in other fields of general machinery. For example, in the manufacture of fans, parts such as impellers and casings are often made by investment casting. The shape and size of the fan impeller have a significant impact on its ventilation performance. Investment casting can produce high-precision impellers that meet design requirements and improve the working efficiency of the fan. In agricultural machinery, some key components, such as the seed meter of the planter and the cutting parts of the harvester, also use investment castings. These components need to have good wear resistance and precision to ensure the normal operation and operation quality of agricultural machinery. Investment casting can meet the requirements of these components for material properties and dimensional accuracy, and improve the reliability and service life of agricultural machinery.
2. Advantages of investment castings in general machinery applications
High precision and high-complexity shape forming capability
Many parts in general machinery have complex shapes and extremely high dimensional accuracy requirements. The investment casting process can accurately replicate the shape of the mold and produce castings with complex internal structures and fine appearance features. For example, when manufacturing the impeller of pump parts, the twist angle, thickness change, and shape and size of the flow channel of the blades can be accurately controlled to ensure the fluid dynamics performance of the impeller when rotating at high speed. Compared with other casting processes, investment casting has obvious advantages in achieving complex shapes and high precision, which can reduce the workload of subsequent machining, reduce production costs, and improve the quality and performance of parts.
Good material adaptability
Investment casting can use a variety of metal materials, including various alloy steels, carbon steels, stainless steels, aluminum alloys, copper alloys, etc. Different general mechanical parts need to use different materials according to their use environment and performance requirements. For example, in the chemical industry, stainless steel or corrosion-resistant alloy materials are often used to manufacture pump bodies and valve parts due to the corrosive nature of the medium; in general machinery in the aerospace field, in order to reduce weight and improve performance, lightweight and high-strength materials such as aluminum alloys and titanium alloys are widely used. The investment casting process can adapt to the casting requirements of these different materials, and ensure that the quality and performance of the castings meet the design requirements by reasonably adjusting the process parameters.
Improve the comprehensive performance of parts
By optimizing the process parameters of investment casting, such as pouring temperature and cooling rate, the internal structure and performance of the casting can be controlled. During the casting process, the appropriate cooling rate can enable the casting to obtain a fine and uniform grain structure, thereby improving the strength, toughness and wear resistance of the parts. For example, when manufacturing high-load parts such as crankshafts and connecting rods of compressors, by accurately controlling the casting process, the internal structure of the casting can be made dense, the grains can be refined, the fatigue strength and impact resistance of the parts can be improved, and the service life of the parts can be extended.
Reduce production costs
Although the initial mold production cost of investment casting is high, for mass-produced parts, due to its high precision and little or no processing, it can significantly reduce the overall production cost. High-precision castings reduce the process and time of subsequent mechanical processing, reducing processing costs. At the same time, due to the reduction of processing allowances, material utilization is improved, further reducing material costs. In addition, the high stability and reliability of the investment casting process and the relatively low scrap rate also help to reduce production costs.
Shorten the production cycle
Compared with some traditional machining methods, investment casting can directly produce parts close to the final shape, reducing the processing steps and time, thereby shortening the production cycle. For some parts with complex shapes and difficult processing, traditional processing methods may require multiple clamping and multiple processes to complete, while investment casting can be formed in one go, greatly improving production efficiency. In today's increasingly competitive market, shortening the production cycle is of great significance for enterprises to quickly respond to market demand and improve market competitiveness.
Investment castings have a wide range of applications and an important position in the field of general machinery. Its advantages such as high precision, high-complexity shape forming ability, good material adaptability and the ability to improve the comprehensive performance of parts provide strong support for the development of general machinery. With the development of process innovation, digital technology integration, high-performance material application expansion and green and environmentally friendly casting technology, investment casting will usher in a broader development prospect in the field of general machinery. Ningbo Suijin Machinery Technology Co., Ltd. specializes in the production of various precision castings and machined parts, including carbon steel, alloy steel and stainless steel, and can perform composite processing of composite materials according to the requirements of the drawings. It plays a greater role in promoting technological progress and industrial upgrading in the general machinery industry.