Centrifugal Casting Manufacturers

How to avoid porosity defects in centrifugal casting

In the field of modern industrial manufacturing, centrifugal casting is widely used in the manufacture of key components in high temperature, high pressure and strong corrosive environments due to its advantages of high density, uniform structure and excellent mechanical properties. Especially in high-performance products such as high-alloy pipes, heat treatment equipment parts, metallurgical rollers, etc., centrifugal casting has irreplaceable technical advantages.
However, one of the most common and most vigilant defects in the centrifugal casting process is porosity. Porosity not only affects the appearance quality of the casting, but also may cause serious degradation of mechanical properties and even lead to early failure in service. Wuxi Dongmingguan Special Metal Manufacturing Co., Ltd. has long been committed to the optimization and quality control of centrifugal casting technology, accumulated rich practical experience, and relied on advanced simulation and testing equipment to effectively reduce the porosity defect rate and ensure the stable performance of products under complex working conditions.
Brief analysis of the causes of pores
The generation of pores in centrifugal casting is mainly related to the following factors:
The gas content of the melt is too high: During the smelting and pouring process, the liquid metal absorbs a large amount of hydrogen, oxygen, nitrogen, etc., forming closed bubbles.
Severe turbulence in the pouring process: Unreasonable pouring speed and mode cause the gas to be drawn into the molten metal and trapped in the tissue during cooling.
Poor mold exhaust: The mold design fails to fully consider ventilation, resulting in gas retention in the mold.
Irrational speed control: Insufficient or excessive centrifugal force may hinder the migration and discharge of gas to the center.
Volatilization of alloy elements or generation of reactive gases: At high temperatures, some alloy elements may decompose and release gases. If not controlled, micropores are easily formed.
Solutions and technical paths of Wuxi Dongmingguan
Dongmingguan has been deeply involved in the field of high-end centrifugal casting for many years, especially in the manufacture of high-alloy centrifugal castings such as radiation tubes, high-temperature furnace rollers, papermaking rollers, and grate bars of waste incinerators. It has a mature and stable process system. In order to effectively avoid the generation of pores, the company has built a complete set of systematic solutions from raw material control, process design, simulation analysis to detection feedback:
1. Strict raw material control and smelting management
The company is equipped with direct reading spectrometers and handheld spectrometers to implement full-process detection of the content of gas-sensitive elements (such as H, O, S, etc.) in raw materials. During the smelting process, the gas content in the melt is controlled by using refining agents and degassing devices (such as vacuum degassing or inert gas purging) to reduce the potential risk of pores from the source.
2. Intelligent casting process simulation
Through the ANYCASTING casting process simulation system, dynamic analysis and visual modeling of molten metal flow, gas migration path, and mold exhaust area are performed to identify turbulent areas, stagnant gas areas, and potential closed gas mass generation areas in advance to achieve targeted improvements. This digital prediction technology makes the process design more scientific and reliable, and the probability of pores is greatly reduced.
3. Optimize pouring and speed control parameters
In the centrifugal casting process, speed control is the core link to avoid pores. Dongmingguan adjusts the speed range (such as 500-1500rpm) according to different product structures and material characteristics, and sets the optimal linear speed distribution in combination with the wall thickness and length of the casting to ensure that the molten metal generates sufficient centrifugal force during high-speed rotation, effectively pushing light impurities and bubbles to the inner surface or central cavity.
In addition, the progressive pouring process reduces the impact speed of the liquid metal into the mold, suppresses the generation of turbulence, and adopts an oblique pouring or bottom pouring mold structure to improve the filling stability and further reduce the air entrainment phenomenon.
4. Fine mold design and ventilation system layout
During the mold design stage, the company's technical team uses CAD/UG for three-dimensional modeling, reasonably sets exhaust channels and ventilation plug holes to ensure that during high-speed rotation, excess gas in the mold cavity can be discharged smoothly to avoid stagnant gas forming pores.
5. Strict quality inspection and feedback closed loop
The finished castings undergo a series of non-destructive testing methods such as ultrasonic flaw detection, magnetic particle flaw detection, and air tightness testing, combined with crystal phase analysis, 3D scanning and geometric comparison to accurately locate the source of defects and form a closed-loop feedback mechanism for process data. This process not only improves product consistency, but also provides a scientific basis for subsequent process improvements.

How to avoid inclusion defects in centrifugal casting

In the modern casting industry, inclusion defects (inclusions) are one of the important factors affecting the internal quality and service performance of metal castings. Inclusions not only weaken the mechanical properties of the material, but may also cause safety hazards such as cracks, leakage, and fatigue failure. Especially for castings in high temperature, high corrosion, and high load environments, it is crucial to control the generation and distribution of inclusions. As an efficient casting method, centrifugal casting (Centrifugal Casting) provides a structural advantage for avoiding inclusions with its unique process principles.
Cause analysis of inclusions in castings
Inclusions mainly come from the following aspects:
Oxidation inclusions and slag inclusions during smelting;
Foreign matter brought into the mold or pouring system;
Particles generated by the reaction of non-metallic elements in the alloy composition;
Slag or solid phase particles that are not effectively separated during refining and pouring.
Once these inclusions remain in the casting, they will significantly affect its density, uniformity and fatigue strength. Therefore, in high-end application scenarios, such as radiation tubes, furnace rollers, high-temperature pipelines and other components, effective control of inclusions has become one of the key indicators of casting quality.
How to structurally avoid inclusion defects in centrifugal casting
The centrifugal casting process itself has the physical characteristics of natural "removal of inclusions":
Centrifugal separation effect
In a high-speed rotating mold, the molten metal moves rapidly to the mold wall under the action of centrifugal force, while the low-density inclusions and gases are thrown to the center or top, thereby being "physically removed" and concentrated in the center of the casting or the riser area. This makes the actual finished product area (tube wall, sleeve, etc.) pure in structure and extremely low in impurity rate.
Dynamic solidification process
Centrifugal casting realizes a dynamic process of solidification layer by layer "from outside to inside". The outer layer solidifies first to form a shell, and inclusions are not easily wrapped in the solidification layer. At the same time, it is also easier to concentrate in the center of the casting with the residual melt in the later stage of pouring and be removed by subsequent processing.
Applicable to clean alloy system
The heat-resistant, wear-resistant and corrosion-resistant alloys produced by Wuxi Dongmingguan, such as high chromium, high nickel, nickel-based alloys, high-sulfur free-cutting steel, etc., have stable composition and high control precision, and are particularly suitable for centrifugal casting to obtain the ideal effect of uniform organization and low inclusion content.
Dongmingguan's inclusion control measures: technology + management double guarantee
As a professional manufacturer with an annual casting capacity of 5,000 tons, Wuxi Dongmingguan adopts full-process management in inclusion control:
1. Control inclusion generation from the source
Raw materials are inspected upon entry into the factory, and direct reading spectrometers and handheld spectrometers are used to detect metal purity;
Strict pretreatment before smelting, and various alloy elements are optimized according to the ANYCASTING simulation results;
Pre-furnace refining and slag removal process control, such as standardized use of slag adsorbents and fluxes;
Pre-furnace temperature and metallurgical reaction time are accurately controlled to avoid overheating or metal burning.
2. Process design ensures the external discharge of inclusions
The design of centrifugal casting molds fully considers the combination of inclusion collection area and riser system;
Control the rotation speed and pouring flow rate to optimize the metal flow state and reduce turbulence;
Preheat the mold to the set temperature before use to avoid slag inclusion caused by cold metal;
Closed management during the pouring process to prevent external dust pollution.
3. Multi-dimensional detection methods ensure the purity of the finished product
Dongmingguan is equipped with a number of high-end detection equipment:
Ultrasonic flaw detector can detect inclusions and their distribution depth;
Magnetic particle flaw detector identifies tiny non-metallic foreign matter;
3D laser scanner + GEOMAGIC comparison analysis system can achieve high-precision comparison of product size and design model, and assist in discovering internal tissue abnormalities;
Crystal phase analyzer evaluates the purity of microstructure;
All test data are archived and managed through a digital system to achieve full quality traceability.

What types of parts are suitable for centrifugal casting?

In the field of modern metal manufacturing, centrifugal casting is an efficient and high-quality metal forming process. Due to its unique process mechanism and excellent finished product quality, it plays an irreplaceable role in many high-end industrial fields. This process uses high-speed rotating molds to evenly distribute liquid metal on the mold wall under the action of centrifugal force, thereby producing high-performance castings with uniform wall thickness, dense structure, and impurities concentrated in the center or excluded. Compared with traditional static casting, centrifugal casting has significant advantages in structural strength, internal quality and finished product life.
As a professional special metal casting company, Wuxi Dongmingguan Special Metal Manufacturing Co., Ltd. has long been committed to the research and development and manufacturing of centrifugal casting products of heat-resistant, wear-resistant and corrosion-resistant alloys. Relying on its superior geographical location on the shore of Taihu Lake and strong technical strength, it continues to expand the application field of centrifugal castings to meet the diverse needs of domestic and foreign customers for high-performance parts.
What types of parts are suitable for centrifugal casting?
Centrifugal casting is best at producing parts with symmetrical hollow structures, high axial strength requirements, and high temperature and high pressure corrosion resistance. According to Dongmingguan's production experience, applicable parts can be roughly classified as follows:
1. High-temperature heat treatment equipment parts
These parts need to operate for a long time in a high temperature environment (generally 800℃~1200℃), requiring the material to have excellent oxidation resistance, thermal fatigue resistance and organizational stability. Centrifugal casting can significantly improve the density and thermal deformation resistance of parts, and is an ideal choice for manufacturing such equipment parts.
Typical products:
Radiant Tubes
Furnace Bottom Rollers
Conveyor Rollers
Heat treatment fixtures, hangers, etc.
Wuxi Dongmingguan has provided centrifugally cast radiant tubes and furnace rollers in batches to many well-known domestic and foreign heat treatment equipment manufacturers (such as Epson, Aixie Lin, Fengdong). In actual use, they have shown long life and excellent high temperature stability, successfully replacing many imported similar products.
2. Rollers for metallurgy and steel rolling industry
Rollers in metallurgical equipment are usually subjected to complex mechanical loads and thermal cycles, and have extremely high requirements for structural strength and resistance to thermal cracks. Centrifugal casting can not only ensure uniform structure and no shrinkage cracks, but also further improve the performance and cost-effectiveness of rollers through the design of inner and outer alloys.
Typical products:
Cold rolling heating furnace rollers
Hot rolling pressing rollers
Conveyor rollers, straightening rollers, etc.
The high alloy furnace rollers, glass rollers, and galvanized tank sinking rollers produced by Dongmingguan are widely used in high-temperature continuous production lines such as steel and glass. They have been exported to Europe, Japan, South America and other countries and regions, and are well received by customers.
3. Wear-resistant/corrosion-resistant pipeline products
For pipelines in industries such as petroleum, chemical, papermaking, and environmental protection that need to transport corrosive or high-temperature media for a long time, traditional casting is difficult to meet their service life requirements. The centrifugal casting process can achieve a dense pipe wall structure, defect-free structure, and no sand holes and pores on the inner wall, thereby greatly improving the corrosion and pressure resistance of pipe fittings.
Typical products:
High sulfur free-cutting centrifugal cast pipes
High chromium and high nickel alloy heat-resistant pipes
Nickel-based or iron-based high alloy corrosion-resistant pipes
Pulp rollers, conveyor rollers, sinking pipes
Dongmingguan can produce various centrifugal cast pipe products with outer diameters ranging from 50mm to 1000mm and lengths up to 4000mm, and can customize alloy composition, heat treatment and mechanical processing integrated services according to customer requirements, providing multi-scenario solutions for the petrochemical and energy industries.
4. High-load hollow rotating parts
Such as engine cylinder liners, wear-resistant sleeves, bearing sleeves, etc., these parts usually have high requirements for dimensional accuracy, wear resistance and concentricity of inner and outer circles. Centrifugal casting can significantly improve the coaxiality of parts and reduce processing allowances, and is a cost-effective choice for mass production of such structural parts.
Advantages of centrifugal casting in Wuxi Dongmingguan
Strong process capabilities: annual casting capacity of 5,000 tons, with a variety of mold specifications and speed control capabilities, to meet the centrifugal casting needs of various sizes and materials.
Specialized materials: Focusing on heat-resistant, wear-resistant and corrosion-resistant alloy systems, it can accurately match various high-condition usage scenarios.
Complete equipment: Equipped with heat treatment equipment such as annealing furnaces and normalizing furnaces, as well as full-process processing equipment such as lathes, milling machines, and boring machines, to achieve integrated delivery from casting to finished products.
Leading quality control: Complete testing equipment, including direct reading spectrometers, crystal phase analyzers, 3D scanners, ultrasonic flaw detectors, magnetic particle flaw detectors, etc., to provide customers with full-process quality assurance.
Advanced software support: Introducing software platforms such as ANYCASTING simulated casting and ABAQUS stress simulation to improve process controllability and reduce trial and error costs.