This article focuses on the application of casting elements in the production of automobile brake discs. It begins with an introduction to the importance of the automotive braking system and the significance of brake discs as key safety components. The casting elements, a new type of material developed by Shandong Xuguang Derui High-tech Materials Co., Ltd., are described in detail, including their composition, characteristics, and advantages over traditional materials such as pulverized coal and bentonite. The article then explores the green, environmental, and low-emission features of casting elements, presenting data on reduced harmful gas emissions and solid waste. The performance of casting elements in clay sand is analyzed through experimental research, and their practical applications in various brake disc production scenarios are presented with case studies. Finally, the article concludes that casting elements offer a promising alternative for the casting industry, providing benefits such as improved casting quality, reduced emissions, and enhanced production efficiency.
1. Introduction
The automotive braking system is a crucial safety feature of a vehicle, and the brake disc is an essential component within this system. Brake discs are typically produced through sand casting processes, and in China, regions such as Yantai, Longkou, and Laizhou in Shandong are major production bases for automobile brake discs and brake drums. These areas account for over 90% of the total domestic production in terms of export volume and supply to domestic and foreign vehicle manufacturers.
In recent years, a new material called casting elements has emerged and has been successfully applied in the production of brake discs and brake drums. This material offers several advantages over traditional casting materials and has the potential to revolutionize the casting process.
2. Casting Elements: An Overview
2.1 Composition and Properties
Casting elements are a unique blend of materials developed by Shandong Xuguang Derui High-tech Materials Co., Ltd. The material consists of high-quality bentonite, a high-carbon and environmentally friendly anti-sticking sand material that replaces pulverized coal, α-starch, cellulose, and other components. This combination results in a mixture that has the characteristics of a mixed soil while also containing a substitute for pulverized coal and a different preparation method compared to traditional mixed soils.
The technical indicators of casting elements vary depending on the model. For example, the XZ80 model, which is recommended for brake disc and brake drum casting production, has specific values for parameters such as blue absorption, wet compressive strength, hot wet tensile strength, micro-volatility, volatile content, bright carbon, and particle size 通过率 (as shown in Table 1).
Table 1: Technical Indicators of Casting Elements (XZ80 Model)
| Parameter | Value |
|---|---|
| Blue Absorption (g/100g) | ≥30 |
| Wet Compressive Strength (kPa) | ≥95 |
| Hot Wet Tensile Strength (kPa) | 3.2 – 3.8 |
| Micro-Volatility (%) | 10 – 12 |
| Volatile Content (%) | 9 – 18 |
| Bright Carbon (%) | 3 – 5 |
| Particle Size 通过率 (140 目) (%) | ≥90 |
2.2 Advantages over Traditional Materials
- Environmental Benefits: The use of casting elements reduces harmful gas emissions and solid waste compared to traditional materials. The replacement of pulverized coal with an environmentally friendly high-carbon material eliminates air pollution and black pollution caused by pulverized coal. Additionally, the reduced solid emissions contribute to a cleaner working environment.
- Improved Performance: Casting elements improve the performance of molding sand. The mixture overcomes issues such as large amounts of harmful gas and solid emissions, spontaneous combustion of pulverized coal, and black pollution associated with traditional bentonite and pulverized coal mixtures. The properties of the molding sand, such as wet compressive strength and permeability, are enhanced.
3. Green, Environmental, and Low-Emission Features
3.1 Reduced Harmful Gas Emissions
The use of casting elements significantly reduces harmful gas emissions. As shown in Table 2, tests conducted by the Shandong Testing Center on samples from the exhaust pipes of the dust removal system in a casting workshop’s molding line for brake discs and brake drums revealed that the harmful gases produced by casting element molding sand were much lower than those produced by pulverized coal and bentonite mixtures. For example, the emissions of sulfur dioxide (SO₂), various hydrocarbons such as benzene, toluene, xylene, etc., were significantly reduced.
Table 2: Harmful Exhaust Gas Monitoring Results
| Detection Date | Detection Project | 2020-04-17 (Pulverized Coal + Bentonite) | 2020-05-20 (Casting Elements) |
|---|---|---|---|
| SO₂ (mg/m³, kg/h) | Measured Concentration, Emission Rate | 6, 0.0598 | 3, 0.0301 |
| Hydrocarbons (mg/m³, kg/h) | Measured Concentration, Emission Rate | Various values (see original table) | Significantly reduced values (see original table) |
3.2 Decreased Solid Emissions
In a casting workshop, sand treatment dust and discarded old sand are major sources of solid emissions. Casting elements reduce solid emissions in several ways. The burnout rate of solid powder materials during high-temperature pouring is decreased, reducing the need for new sand addition to maintain the mud content of the molding sand and adjust its properties. As a result, the amount of dust removed during sand treatment and the amount of discarded old sand are reduced.
For example, in a company’s casting workshop with 3 Japanese-imported horizontal unboxing injection molding lines sharing a sand treatment line for brake disc and brake drum casting, after using casting elements, the addition of auxiliary materials decreased from 0.74% to 0.44%, the mud content of the molding sand decreased, and instead of adding new sand, 0.3% of the dust removed was recycled to maintain the mud content within the required range. This led to an 80% reduction in solid emissions (as shown in Table 3).
Table 3: Molding Sand Ratio Before and After Using Casting Elements
| Material Name | Old Sand (kg) | New Sand (kg) | Bentonite (kg) | Pulverized Coal (kg) | Casting Elements (kg) | Dust Removed (kg) |
|---|---|---|---|---|---|---|
| Original Process | 2700 | 4 | 14 | 6 | 0 | 0 |
| New Process | 2700 | 0 | 0 | 0 | 12 | 9 |
4. Performance of Casting Elements in Clay Sand
Researchers at Shandong Jianzhu University conducted experimental studies to evaluate the performance of casting elements in clay sand. The XZ80 model of casting elements was compared with other similar materials, and the process properties of clay sand mixed with casting elements, bentonite, and pulverized coal were studied.
The results showed that:
- The blue absorption and volatile content of 1 g of casting elements were equivalent to those of 1.271 g of bentonite I and pulverized coal or 1.248 g of bentonite II and pulverized coal.
- The wet compressive strength and permeability of clay sand containing casting elements changed with the amount of casting elements and water in the same way as those of clay sand containing bentonite and pulverized coal.
- When not controlling the total mud content, the wet compressive strength and permeability of clay sand containing casting elements were higher than those of clay sand containing equivalent amounts of bentonite and pulverized coal.
- When the total mud content accounted for 13% of the molding sand mass, the wet compressive strength of clay sand containing casting elements was higher than that of clay sand containing equivalent amounts of bentonite and pulverized coal, and the permeability was slightly higher or equal to that of the latter.
5. Applications in Brake Disc and Brake Drum Production
5.1 Case Studies
- Case 1: A company’s casting workshop with 4 Japanese-imported horizontal unboxing injection molding lines for producing automobile brake discs and brake drums initially used pulverized coal and bentonite, with a casting yield of 93% and about 80% of the defective products being due to porosity. After using casting elements, the amount of casting elements added was less than the sum of bentonite and pulverized coal, the mud content of the molding sand decreased from 11.5% – 13% to 10% – 12%, the water content decreased from 3.4% – 3.8% to 3.0% – 3.5%, and the porosity defects in the castings significantly decreased. By further adjusting the compaction rate of the molding sand at the sand outlet of the mixer, the casting yield was finally stabilized at 95% – 96%.
- Case 2: A company’s casting workshop with 2 Japanese-imported vertical parting unboxing injection molding lines for producing single-piece brake discs and brake drums without cores faced a contradiction between increasing the wet compressive strength and increasing the collapsibility of the molding sand. After using casting elements, the amount of casting elements added was reduced to half of the original amount of bentonite and pulverized coal, the wet compressive strength, mud content, and compaction rate of the molding sand returned to normal, the collapsibility and sand removal properties of the molding sand improved, and the problems of sand-carrying and sticking in the blank holes were solved.
- Case 3: A company’s casting workshop with 3 Japanese-imported horizontal unboxing injection molding lines for producing automobile brake discs and brake drums using a double-layer molding process faced problems such as decreased toughness and increased brittleness of the molding sand. After using casting elements, the toughness and demolding performance of the molding sand were restored, the addition of new sand was cancelled, and the defective rate of the castings decreased.
- Case 4: A company’s casting workshop with 3 Japanese-imported horizontal parting unboxing injection molding lines for producing brake discs faced problems such as peeling, rat-tail, and veining defects near the small end root of larger diameter brake discs. After using casting elements, the amount of casting elements added was reduced by 54% compared to the sum of bentonite and pulverized coal, the problems of peeling, rat-tail, and veining were solved, and the defective rate of the castings decreased.
5.2 General Benefits in Production
In general, the application of casting elements in brake disc and brake drum production has the following benefits:
- Reduced Material Consumption: The amount of casting elements added is less than the sum of pulverized coal and bentonite, reducing material costs.
- Improved Casting Quality: The porosity, sand holes, sticking, peeling, rat-tail, veining, and deformation defects of the castings are reduced, improving the quality of the castings.
- Enhanced Production Efficiency: The performance of the molding sand, such as demolding, collapsibility, and fluidity, is improved, facilitating the production process and increasing production efficiency.
6. Conclusion
Casting elements have proven to be a highly effective and environmentally friendly material for the casting production of automobile brake discs. Their application offers numerous benefits, including reduced emissions, improved casting quality, and enhanced production efficiency. As the casting industry continues to seek ways to improve sustainability and product quality, casting elements provide a viable solution. With further research and development, it is expected that the application of casting elements will become even more widespread, contributing to the advancement of the casting industry as a whole.
For enhanced readability, relevant images could be added to illustrate the following aspects:
- The structure and components of an automobile braking system, highlighting the position and importance of the brake disc.
- The production process of brake discs, showing the steps involved in sand casting and the use of different materials.
- The comparison of the appearance and performance of brake discs produced with traditional materials and casting elements, demonstrating the quality improvements achieved with casting elements.
- The environmental impact of the casting process, such as the reduction in emissions and waste when using casting elements.