Comparison of cooling efficiency between water-cooled wheel hub molds and air-cooled molds
The cooling time of water-cooled molds is 20% -35% shorter, suitable for mass production lines; The air-cooled structure is simple and maintenance efficient, suitable for small and medium-sized batches.
The cooling time accounts for the largest proportion of the entire beat
Low pressure casting of an 18 inch wheel hub, with a single-mode cycle typically lasting 8-12 minutes. The cooling stage accounts for 30% -50% of it and is the main battlefield for rhythm optimization.
Pressing the cooling time from 4 minutes to 2.8 minutes can reduce the single-mode cycle by about 15%. According to the three shift system, the daily production capacity will increase by nearly 100 pieces.
The value of water cooling lies not in the mold itself, but in turning this waiting period into a controllable variable. Air cooling relies more on ambient temperature and workshop airflow.
The waterway structure determines the heat transfer efficiency
The water-cooled mold is equipped with independent circuits on the wheel rim and spoke, with a water passage spacing of 30-50mm. If the spacing is too large, there will be a significant temperature gradient on the surface of the mold cavity.
The air-cooled mold relies on the heat dissipation ribs at the back of the mold cavity and the fan for forced convection. The heat transfer coefficient is one order of magnitude lower than that of water cooling, and the temperature fluctuation of the mold can reach ± 15 ℃.
Water cooling can stabilize the mold temperature within the target range of 200-350 ℃ and narrow the fluctuation to ± 5 ℃. Temperature stability improves the consistency of casting dimensions.
Quality Issues and Costs Caused by Water Cooling
Improper waterway design, low surface temperature of the mold cavity, premature solidification of the aluminum liquid front, and easy occurrence of cold insulation or insufficient pouring of the spokes.
The sealing points of water-cooled molds are more, and the risk of water leakage increases accordingly. It is recommended to conduct a pressure maintenance check every 5000 molds, with a pressure not lower than 0.4MPa.
In terms of mold pricing, water-cooled structures are usually 15% -25% higher than air-cooled structures. If separate temperature control is added, an additional 12000 to 25000 yuan will be charged for each set.
In which scenarios is air cooling more suitable
Factories with single shift production and a daily output of less than 200 pieces have lower comprehensive costs for air cooling. The additional investment in water cooling is difficult to recover by relying on rhythm savings.
In areas with stable ambient temperature and good workshop ventilation, the temperature fluctuations of air-cooled molds can be controlled within an acceptable range. Caution should be exercised during the high humidity season in the south.
Thick walled wheel type or gravity casting molds have slow cooling, and air cooling combined with cold iron can meet the requirements. The marginal revenue of adding water to the road is limited.
Hybrid cooling is becoming a compromise solution
The combination of water-cooled wheels and air-cooled spokes is common. Thin wheel rims, large heat dissipation area, and high water cooling benefits; Thick spokes make air cooling safer.
The mold with partitioned temperature control is usually equipped with 4-8 independent circuits. Each group is equipped with a flow meter and temperature sensor for easy zone by zone debugging.
Xinfeng Mold will label the circuit number and temperature control point on the mold nameplate for the water-cooled wheel hub mold, facilitating on-site debugging according to the diagram and reducing trial and error.
Long term accounts for energy consumption and operation and maintenance
Water cooling requires a chiller or cooling tower, and the power of a single device is often between 5-15kW. The annual electricity bill is a fixed expense that needs to be included in the unit cost.
The power of air-cooled fans is lower, but the cooling effect deteriorates significantly during high temperatures in summer. If necessary, it is necessary to install post air supply, and the actual energy consumption is not zero.
Scaling of water pipes will gradually reduce heat transfer efficiency. It is recommended to clean once every 12 months, and in hard water areas, it should be shortened to 6-8 months.
How to determine which one to choose
First, calculate the rhythm gap. The current production line is more than 15% away from the target production capacity, making it easier to recoup the investment in water cooling.
Look at the wheel shape again. The necessity of temperature control in water-cooled zones is higher for wheel types with wall thickness differences exceeding three times; A wheel with uniform wall thickness and sufficient air cooling.
Finally, consider the operational capability. Factories without dedicated equipment maintenance personnel will increase the risk of water leakage and scaling in the waterway, making air cooling more worry free.
Frequently Asked Questions
Q: How much time can water-cooled molds save?
Answer: The cooling time can be shortened by 20% -35%, and the entire mold cycle can be reduced by about 15%.
Q: Is it easy for water-cooled molds to leak water?
Answer: There are many sealing points, and pressure maintenance checks need to be conducted every 5000 molds.
Q: What is the temperature fluctuation of air-cooled molds?
Answer: Usually ± 15 ℃, water cooling can narrow it to ± 5 ℃.
Q: How much is the cost of water-cooled molds?
Answer: It is 15% -25% higher than air cooling, and the temperature control in different zones is calculated separately.
Q: Is water cooling suitable for small batches?
Answer: When the daily production is less than 200 pieces, the comprehensive cost of air cooling is lower.
Q: How often is the waterway cleaned?
Answer: Regular 12 months, 6-8 months in hard water areas.
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