As a specialized steel castings manufacturer in China, we undertook the design and development of a small-scale investment casting foundry to address the regional demand for high-precision steel components. This project aimed to establish a facility capable of producing 100 tons of high-quality steel castings annually, focusing on products such as hooks for coal mining conveyors, lifting arms for tractors, and shift forks for motorcycles. The design process encompassed factory planning, process optimization, equipment selection, and economic analysis, ensuring operational efficiency and cost-effectiveness. Our goal was to create a model for China casting manufacturers, emphasizing advanced technology and sustainable practices.
The production纲领 was established based on market needs, with a focus on steel castings manufacturer requirements for durability and precision. Key products include components with weights ranging from 0.5 kg to 5 kg, and medium complexity. To account for potential defects, a 5% scrap rate was incorporated into the planning. The facility operates on a two-shift system, with equipment annual time bases set at 4,000 hours and worker annual time bases at 2,000 hours, based on 250 working days per year. The table below summarizes the annual production plan:
| Component Name | Units per Machine | Annual Machine Output | Weight per Piece (kg) | Total Weight (kg) | Number of Mold Groups | Number of Boxes |
|---|---|---|---|---|---|---|
| Hook | 2 | 50,000 | 1.5 | 75,000 | 500 | 100 |
| Scraper | 4 | 25,000 | 2.0 | 50,000 | 400 | 80 |
| Lifting Arm | 1 | 100,000 | 3.0 | 300,000 | 600 | 120 |
| Shift Fork | 2 | 30,000 | 1.0 | 30,000 | 300 | 60 |
| Total | 9 | 205,000 | 7.5 | 455,000 | 1,800 | 360 |
The process design for this steel castings manufacturer facility prioritized rapid shell hardening and high-strength molds, utilizing a no-sand or minimal-sand firing technique to enhance efficiency. Constant temperature and humidity conditions were maintained in the wax injection and shell-building areas to ensure casting quality. The investment casting process employed a blend of paraffin and stearic acid as the pattern material, with sodium silicate as the binder. The overall workflow is illustrated in the following description, which outlines key stages from pattern making to finishing.
Pattern preparation involved using a mixture of 50% paraffin and 50% stearic acid, with 20% recycled wax added to the blend. The wax was melted in a dedicated furnace at a controlled temperature of 70 ± 5°C, stirred to a paste-like consistency, and stored in the injection machine’s reservoir. For wax pattern injection, semi-automatic machines were utilized, with the wax maintained at 55 ± 5°C. After injection, patterns were cooled in water at 18–20°C, inspected, trimmed, and assembled onto wax gating systems using soldering irons. The gating bars were cast from aluminum alloy and machined with steps and internal holes for easy handling and suspension.
Shell building was performed manually by dipping pattern assemblies into a coating slurry, followed by sand application via a rain-type sanding machine. The shells were then hardened in a bath containing a 25% ammonium chloride solution at 25°C. Dewaxing used a hot water method, where shell assemblies were immersed in a tank at 95°C with 3% hydrochloric acid to remove wax and clean the shells. The recovered wax underwent neutralization with 5% hydrochloric acid, boiling for 2–3 hours, followed by stirring, sedimentation, and filtration for reuse. Shell firing was conducted in a 50 kW electric box furnace, with shells entering at 500–600°C, fired at 850–900°C for 2 hours. Metal melting utilized a 100 kg medium-frequency induction furnace, and casting was done manually. After cooling, shells were broken manually, gates were cut off with gas torches and ground smooth, and heat treatment was applied to relieve stresses. Final finishing involved liquid sandblasting to remove scale, with defective castings repaired via welding.
The factory layout was optimized for workflow efficiency, covering a total area of 1,200 m². Key sections included the shell-making workshop, firing and casting area, mold and maintenance workshop, and a central laboratory. Power supply was ensured through a dedicated substation with a total capacity of 200 kVA, supplied by two transformers. A 30 m³ water tower was installed to maintain a pressure of 0.3 MPa, providing cooling for the furnace during power outages. The following diagram illustrates the facility’s arrangement:
Equipment load calculations were critical for ensuring the steel casting manufacturers’ operational efficiency. The metal balance assumed 70% of total metal for合格铸件, 20% for gates and scrap, 5% for scrap rate, and 5% for metal loss and burn-off. The负荷率 for key equipment was computed using the formula: $$ \eta = \frac{\text{Annual Production}}{\text{Annual Time Base} \times \text{Hourly Rate} \times \text{Coefficient}} \times 100\% $$ where the coefficient accounts for operational variables. For instance, the medium-frequency furnace had an annual time base of 4,000 hours, annual production of 100 tons, a coefficient of 0.9, and an hourly rate of 25 kg/h, resulting in a load factor of: $$ \eta_{\text{furnace}} = \frac{100,000}{4,000 \times 25 \times 0.9} \times 100\% = 111.11\% $$ Similarly, the shell-firing furnace, with an annual time base of 4,000 hours, annual firing of 1,800 groups, a coefficient of 0.85, and an hourly rate of 2 boxes/h, had a load factor of: $$ \eta_{\text{furnace}} = \frac{1,800}{4,000 \times 2 \times 0.85} \times 100\% = 26.47\% $$ The semi-automatic wax injection machine, with an annual time base of 4,000 hours, annual production of 50,000 patterns, a coefficient of 0.95, and an hourly rate of 20 patterns/h, showed: $$ \eta_{\text{injection}} = \frac{50,000}{4,000 \times 20 \times 0.95} \times 100\% = 65.79\% $$ Lastly, the sandblasting machine, with an annual time base of 2,000 hours, annual production of 100 tons, a coefficient of 0.9, and an hourly rate of 100 kg/h, achieved: $$ \eta_{\text{sandblasting}} = \frac{100,000}{2,000 \times 100 \times 0.9} \times 100\% = 55.56\% $$ These calculations highlight the balanced load distribution, with room for expansion, as seen in the low load factors for some equipment.
The technical and economic indicators demonstrate the viability of this China casting manufacturers project. The total investment was 1.5 million CNY, with a workforce of 30 people. The facility achieved a unit area annual output of 83.33 kg/m² and a unit production area annual output of 100 kg/m². Each production worker contributed an annual output of 3,333 kg, with a total labor input of 60 hours per ton of合格铸件. The cost per ton of合格铸件 was 15,000 CNY, reflecting competitive pricing for a steel castings manufacturer. The table below summarizes these metrics:
| Indicator | Value |
|---|---|
| Annual Output of合格铸件 (tons) | 100 |
| Total Workshop Area (m²) | 1,200 |
| Production Area (m²) | 1,000 |
| Total Investment (million CNY) | 1.5 |
| Total Workforce | 30 |
| Unit Area Annual Output (kg/m²) | 83.33 |
| Unit Production Area Annual Output (kg/m²) | 100 |
| Annual Output per Production Worker (kg) | 3,333 |
| Investment per Ton of合格铸件 (CNY) | 15,000 |
| Total Labor per Ton of合格铸件 (hours) | 60 |
In conclusion, this small-scale investment casting foundry exemplifies the capabilities of modern steel casting manufacturers in China. By integrating advanced工艺流程, optimized layouts, and rigorous load calculations, we have established a facility that meets high standards for quality and efficiency. The design allows for future expansion, with excess capacity in power load and production area, enabling the addition of equipment to increase output. As a leading China casting manufacturers, this project underscores our commitment to innovation and sustainability in the steel castings industry, providing a replicable model for similar operations globally. The successful implementation, with over 50 types of castings produced and a scrap rate below 5%, validates the design principles and economic feasibility, positioning us as a reliable steel castings manufacturer for diverse industrial applications.