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INDUSTRY LEADING SILICA SOL INVESTMENT CASTING PROCESS
What Is Investment Casting?
Investment casting, also referred to as lost wax casting, designed for the creation of intricate and finely detailed metal components. This method commences with the formation of a wax pattern that replicates the desired part. The wax pattern is then enveloped in a ceramic shell, forming a mold of the component. Subsequently, the wax is melted away from the mold, leaving behind a void that mirrors the intended metal part.
The next step involves pouring molten metal into this ceramic mold cavity. Once the metal cools and solidifies, the ceramic shell is carefully removed, unveiling the finished metal component with exceptional precision and dimensional accuracy.
Investment casting is highly regarded for its ability to produce complex parts with intricate details. It is a preferred method in aerospace, automotive, medical, consumer electronics, agriculture, machinery, construction, engineering, and various other industries where exactness and quality are paramount. This versatile casting technique offers remarkable design flexibility and is well-suited for crafting small to medium-sized components with intricate features. Whether you need a single prototype or a large-scale production run, our investment casting service can meet your specific needs with precision and expertise.
At Taiyuan Simis Investment Casting Co., Ltd., we utilize the world’s most advanced silica sol investment casting process across two dedicated foundry workshops. This innovative technique allows us to cast a wider range of materials, extending beyond stainless steel to include carbon and alloy steels, offering greater flexibility for our clients. Our silica sol process significantly enhances casting quality, particularly surface finish, while also reducing costs. One workshop focuses on producing alloy steel and carbon steel castings using this advanced technique, while the other is dedicated to casting stainless steel parts and components.
Our Advanced Investment Casting Process
1. Tooling design and manufacturing
Tooling design in investment casting is the process of crafting wax or plastic patterns that precisely mirror the shape, dimensions, and intricate features of the desired metal component. These patterns serve as the molds for the molten metal during the investment casting process. Tooling designers employ computer-aided design (CAD) software to create highly accurate digital models, accounting for factors such as shrinkage compensation, gating system design, and venting.
With over 40 years of experience of providing investment casting service, Taiyuan SIMIS Investment Casting Co. Ltd specialises in the independent design and in-house manufacturing of tools tailored for investment casting. Our expertise extends to a diverse range of mold types, including automatic wax injection molds, manual wax injection molds, and automatic opening molds, all designed to accommodate various casting structures. We take pride in our ability to provide custom tooling design, tailored to fit different wax machines and specific casting requirements, ensuring precision and quality throughout the investment casting process.
2. Wax Mold Production
To accommodate various structures and quantities of investment castings, we possess multiple types of wax injection machines, including fully automatic, semi-automatic, and manual models. Additionally, we have a fully automated system for mold material preparation and recovery. Following the creation of the wax molds, we carefully inspect its dimensions and surface quality, making necessary repairs as needed. Subsequently, depending on the casting structure, the wax mold is affixed to the gate or riser wax rod to prevent any shrinkage holes in the casting. The assembled wax tree, formed by welding, is conveyed through an automated line to undergo the shell-making process.
3. Shell Making Process
At Taiyuan Simis Investment Casting Co., Ltd., our investment casting process has undergone significant technological advancements, particularly in shell-making, positioning us ahead of 90% of our domestic competitors in quality, cost-effectiveness, and environmental sustainability.
Key innovations include replacing the traditional water glass binder with silica sol, eliminating the need for environmentally harmful hardening solutions like ammonium chloride or aluminum chloride. This change not only enhances the working environment but also significantly improves the quality of our castings. We’ve also dramatically reduced the air-drying time for silica sol shells from eight hours per layer to just one hour, enhancing both production efficiency and shell strength.
Our advanced silica sol process now accommodates a broader range of materials, including carbon steel and various alloy steels, and can produce investment casting parts up to 50kg. This expansion has notably reduced costs, particularly for materials previously considered expensive to process with silica sol investment casting technique.
Moreover, our shell-making process is fully automated, with robotic arms performing all tasks including air-drying. Each of the up to eight shell layers is managed by a dedicated robot and drying chamber, ensuring consistent quality and eliminating human error. The shells produced are significantly stronger and thinner than those made with traditional binders, improving breathability and resulting in castings with superior surface quality.
4. Mold Dewaxing
The silica sol shell process, a part of the investment casting process, exclusively employs the steam dewaxing technique. We employ a sizeable 3m³ dewaxing machine operating at 0.7MPa pressure, ensuring the efficient removal of wax within a 30-minute timeframe. Following dewaxing, the interior of our high-strength shell showcases a lustrous, ceramic-like finish. The surface roughness and dimensional precision of the castings we produce exceed those achieved through the use of water glass binders by two grades.
5. Shell Firing
Shell Firing is a crucial step in our investment casting process, and at the heart of this operation lies our indispensable calcining shell kiln. To accommodate the high-strength characteristics of our shells, we rely on a tunnel kiln spanning an impressive 30 meters in length, meticulously heated using pollution-free natural gas. The shells undergo a gradual heating process, commencing at a low-temperature 200°C calcination and gradually reaching a high-temperature 950°C calcination.
This deliberate approach safeguards against deformation or cracking induced by sudden temperature changes. Ultimately, the calcining process in our state-of-the-art kiln ensures the shells attain the requisite strength and precision vital for our investment casting process.
6. The smelting and pouring
The smelting and pouring is one of the most important phases in the entire investment casting process, representing one of the core strengths of our company. We possess the expertise to precisely smelt various materials, ensuring that the chemical composition requirements of the investment castings are met.
In addition to carbon steel, we excel in handling specialised steel types, including high-alloy steel, stainless steel, heat-resistant steel, wear-resistant steel, high manganese steel, and other distinctive steel alloys.
Our commitment to quality extends to the stability of molten steel’s chemical composition, free from impurities or internal defects such as pores. Before tapping the molten steel, we subject it to three spectral inspections to verify its composition and perform temperature checks twice using a thermocouple. We employ the finest deoxidisers and slag-making agents available in China to guarantee the quality of each casting.
During pouring, we utilise Teapot ladles, effectively preventing impurities from entering the castings. Furthermore, we conduct secondary deoxidation in the ladle to further enhance the internal quality of the castings.
7. Cooling, Solidification, and De-Shelling
After the precise pouring of molten metal into ceramic shell molds, an important step in the investment casting process, castings undergo cooling, solidification, and de-shelling. De-shelling involves meticulously removing the ceramic shell material. Simis enhances this stage with the most advanced hanging-type fully automatic equipment, the equipment automatically removes dust and adopts a suspension method to prevent damage to the surface of the castings during shell removal, greatly reducing the labor intensity and ensuring efficient and precise shell removal and dust removal.
Once de-shelling is complete, the castings emerge, revealing their intricate shapes. They then move on to finishing, quality control, and inspection stages, ensuring they meet rigorous standards. The ‘Cooling, Solidification, and De-Shelling’ stage is pivotal, shaping castings into their final form before further refinement and quality checks.
8. Finishing and Inspection
This is the last stage in the investment casting process, it is vital for ensuring that our investment castings meet stringent quality standards and specifications, providing our customers with products of exceptional quality and precision.
At Simis, we take quality assurance seriously, our dedication to producing high-quality castings is backed by our ISO9000 quality management system and TS16949 certification, which form a strong foundation for our quality assurance practices.
We’ve established a fully-equipped casting mechanical properties and chemical composition analysis testing center. This Top-of-the-line facility allows us to comprehensively analyze and test the chemical composition and mechanical performance of different materials. Our key equipment includes:
- Spectrometer
- Mechanical performance tensile testing machine
- Impact equipment capable of performing room temperature and low-temperature (-45°C) impact tests, complete with machined impact test piece notch equipment
- Metallographic inspection equipment
- Rockwell hardness tester
- X-ray detection equipment
- Ultrasonic detector
- Magnetic particle flaw detection equipment
- Penetrant testing
The results of these rigorous tests and analyses, along with corresponding samples, are meticulously archived and organized by date and customer. We also provide detailed inspection reports to our valued clients, ensuring transparency and quality assurance throughout the entire investment casting process.
Advantages of Our Investment Casting Process
At Taiyuan Simis Investment Casting Co. Ltd., we take pride in elevating the inherent advantages of the investment casting process to deliver unparalleled quality and precision. As a leading China investment casting foundry with over four decades of experience, we offer precision investment casting services to cater to diverse industries, making us a trusted name in the foundry industry.
Intricate Designs and Complex Geometries
Our investment casting process is excellent for making intricate and highly detailed parts, giving you great design freedom. At Taiyuan SIMIS, our skilled engineers use this investment casting process to make sure every part meets the highest industry standards. Our expert tooling design is key to creating these complex shapes. We use advanced software and techniques to make precise tools that accurately copy the desired part, including fine details.
For complex internal shapes and undercuts, we use ceramic cores. These cores are carefully placed in the mold and removed after casting, leaving the exact internal features. This combination of the investment casting process, our engineering skills, and advanced tooling lets us make parts with intricate details and complex shapes that are hard or impossible to make with other methods, saving you money on extra machining and assembly.
Excellent Surface Finish
Our investment casting process is known for creating parts with a superior surface finish, a result of both our meticulous process control and the use of high-quality materials. We carefully select premium wax for creating accurate patterns, high-grade refractory materials for building durable ceramic shells, and appropriate alloys for the final castings. By controlling every stage of the investment casting process, from the initial wax pattern creation to the final pouring of molten metal into the ceramic shell, we ensure smooth surfaces and excellent results.
This combination of high-quality materials and precise process control means you often get parts with a finished look right out of the mold, minimizing or eliminating the need for additional finishing.
Tight Tolerances and Dimensional Accuracy
Achieving tight tolerances and high dimensional accuracy is a hallmark of our investment casting process. At Taiyuan SIMIS, we leverage our advanced silica sol process to ensure exceptional precision in every casting. We can cast parts strictly according to your drawing requirements, meeting even demanding tolerances down to CT4 grades. This precision minimizes the need for secondary machining and ensures your parts fit and function as intended.
Material Versatility
One of the key advantages of our investment casting process is our ability to work with a wide range of materials. As a seasoned investment casting foundry, we offer stainless steel, carbon steel, and various alloy steels, such as high-strength, high-nickel, and high-manganese steels, among others. We operate two dedicated workshops to optimize the casting process for each material type: one specializing in stainless steel and the other using our advanced silica sol investment casting process for carbon and alloy steels. This silica sol process allows us to cast parts weighing up to 50kg, making our investment casting services suitable for diverse applications across many industries.
Cost-Effectiveness
For small to medium production runs, our investment casting process offers a compelling cost advantage: significantly lower tooling costs compared to other casting methods. While some tooling investment is required, it’s much less substantial than the tooling required for processes like die casting. This makes investment casting a highly cost-effective choice for smaller volumes. We further enhance this cost advantage through efficient automated systems, such as automated wax injection and shell building (reducing labor), and our deep process expertise (minimizing waste and maximizing efficiency). This results in high-quality parts through our investment casting services at a competitive price.
Top-Notch Quality
Quality is top priority throughout our investment casting process. Our automated systems, particularly our automated drying system, are crucial for achieving consistent, high-quality results. The automated drying system ensures uniform drying of the ceramic shells, minimizing human error and variations in the drying rate. This controlled drying process creates stronger, more consistent shells, which directly translates to higher-quality castings with fewer defects and improved dimensional accuracy. This commitment to automation and precision ensures top-notch quality in every casting.
Repeatability and Consistency
A key benefit of our investment casting process at Taiyuan SIMIS is the high level of repeatability and consistency we achieve. Once the tooling is made, we can produce identical castings in every production run, ensuring consistent quality and performance for every part. This consistency is further supported by our robust production scheduling management system, which ensures consistent delivery and adherence to agreed-upon timelines.
In addition to process control and scheduling, we also prioritize meticulous material management. We utilize dedicated pouring equipment (ladles) for different materials to prevent cross-contamination and maintain the specific properties of each alloy. Our well-organized facility with clearly labeled sections for each customer’s materials further ensures proper handling, storage, and traceability throughout the entire production process.
Reduced Post-Processing
A significant advantage of our investment casting process is the reduced need for post-processing thanks to the near net shape nature of the castings. Because of the inherent precision and excellent surface finish, many parts can be used as-cast, meaning they don’t require additional machining, grinding, or polishing. This near net shape capability saves you valuable time and reduces manufacturing costs.
Wide Applications Across Industries
The versatility of our investment casting process allows us to serve a wide range of industries. Our castings are used in demanding applications across diverse sectors, including aerospace, automotive, railway, energy section, food processing, medical devices, industrial machinery, construction, agriculture, and many others.
Minimizing Environmental Impact
Many investment casting manufacturers in China, especially those using the water glass investment casting process, have faced production delays due to failing local environmental inspections. At Taiyuan SIMIS, we prioritize minimizing our environmental impact through sustainable casting practices. We use advanced environmental protection equipment and employ an environmentally friendly silica sol binder in our investment casting process. This advanced process minimizes material wastage, contributing to a more sustainable manufacturing approach.
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Credentials Beyond Compare
We’re a professional investment casting manufacturer and a member of the China Foundry Association. Our long-held ISO 9001 certification and our TUV certification show our dedication to quality in every aspect of our work. This means our customers can always expect top-quality products and services that meet all their needs and industry standards.
